MANUFACTURING HEAT TREAT TECH Archives

Will In-House Heat Treaters 3D Print the “Cutting Edge”?

If you are one of many heat treat professionals watching AM take over the industrial world with bated breath, it may be time to stop watching and start doing. This article highlights the rapid rise of AM and how changes in your heat treat operations may be needed.

This informative piece was first released in Heat Treat Today’s August 2025 Automotive Heat Treating print edition.

For manufacturers who produce customized or complex parts and components for the medical, aerospace, automotive, and other industries, additive manufacturing (AM) with metals has the potential to bring innovation and agility to the process.

However, because AM is a somewhat nascent technology, there are still challenges to address before it is widely accepted throughout the manufacturing industry. Fortunately, as research and development continue, the aerospace and automotive industries are beginning to acknowledge that parts made via AM are robust enough for use in safety-critical applications. Manufacturers who want to use AM to gain a competitive edge are advised to zero-in on the most suitable method for metals and determine in which applications AM presents an economically viable solution.

The Additive Manufacturing Market

AM, also known as 3D printing, is the process of creating an object based on a digital file, such as a computer-aided design (CAD) or one created with a laser scanner. Unlike traditional manufacturing methods that often involve cutting or subtracting material from a solid block (like machining), AM involves building up thin layers of material — usually metal, ceramic, or plastic — one by one using a 3D printer.

AI-generated image of 3D-printed turbine engine components

AM is increasingly transforming the manufacturing industry, enabling faster prototyping, customized production, lightweight parts, and complex shapes and geometries that would be impossible to manufacture using conventional casting, machining, or subtractive techniques, such as milling, grinding, carving or shaping.

For product design, prototyping, and reverse engineering applications, AM allows designers to rapidly print parts as a single piece, reducing material waste, saving time, and reducing costs, all while getting new products to market faster. Although the same advantages apply to traditional manufacturing applications, manufacturers have not been as quick to adopt the technology.

Still, the AM industry is seeing growth. A recent report from Grand View Research states that the global AM market size was valued at over $20 billion in 2023 and is expected to grow at a CAGR of 23.3% from 2023 to 2030, with unit shipments of 3D printers expected to reach 21.5 million units by 2030 thanks to a growing demand for prototyping applications in the healthcare, automotive, aerospace, and defense industries. The report also acknowledges that rigorous R&D in 3D printing will further contribute to growth.

Additive Manufacturing Techniques for Metals

Currently, three primary techniques are used for AM with metals: laser powder bed fusion (LPBF), directed energy deposition (DED), and binder jetting.

LPBF

LPBF technologies, including direct metal laser sintering, selective laser sintering, and direct metal printing, use a laser to sinter or fuse powdered metal particles until a complete part if formed. LPBF processes typically include heating the bed of powdered metal to a consistent temperature. The printer begins applying the first layer over a build plate, fuses the powder particles together with a high-powered laser, and then continues the process layer-by-layer until the part is finished.

After the part is printed using LPBF, it is removed from the powder bed, cut away from the build plate, heat treated to prevent internal stresses, and finally machined or polished to achieve the desired surface finish.

LPBF is limited by the size of the print bed, so it is not suitable for manufacturing large components or parts.

DED

DED using powdered metals also relies on a laser to produce metal parts. However, rather than spreading powder on a bed, the DED machine blows powdered metal out of the print head and uses a laser to fuse the part during construction.

DED-manufactured parts require post-processing heat treatment and machining steps. And while DED is a faster process than LPBF, there are a limited number of materials that can be used in the DED process, and the technique still needs more research and development before it sees widespread commercial use.

Binder Jetting

Binder jetting deposits a layer of loose metal followed by a layer of binder material layer by layer to create the product. During the process, a binder jetting machine distributes metal powder over the print bed to form an unbound layer. A jetting head then spreads a binder to adhere the powder. The machine continues to spread alternate layers of building material and binder to form a complete product. Sintering is generally required after printing to remove the binder, resulting in a part that is composed entirely of metal.

While binder jetting is a fast process and offers the opportunity to create and sinter parts in batches, it is currently a more expensive option. However, research and development into this technology, the availability of binder jets from companies (e.g., Markforged and HP), and the potential to use binder jetting for high-volume batch production may eventually make binder jetting the technology of choice for metal AM.

Post-Processing Heat Treatment for AM Parts

No matter the print technique, some AM-printed metal parts will require post-process heat treatment in which the printed part is subjected to specific temperatures and durations and then cooled to enhance or customize the properties of the metal material and optimize performance and reliability of the part.

Applying controlled heating and cooling cycles during post-printing heat treatment eliminates internal stresses created during the AM process to prevent distortion, cracking, and warping that would negatively impact part performance and reliability. Heat treating can also be used to increase hardness, density, strength, and fatigue resistance to optimize performance of the part. Furthermore, heat treating can be applied to customize the mechanical properties of the final part and provide specific characteristics so that it performs reliably in the intended application.

The type of heat treatment used following AM will depend upon the printing technique, metal material, and desired characteristics and properties. Annealing, sintering, normalizing, quenching, and tempering are commonly used. Hot isostatic pressing (HIP) — another post-process option that is used to reduce porosity and improve the density, performance, and reliability of AM-printed parts — will be specifically addressed in a subsequent article release.

Greater Acceptance in Industry Sectors

While AM has been widely used for prototyping and reverse engineering, adoption of the technology has been slower for the manufacture of finished parts and components. Stephen Feldbauer, director of Research and Development, with Abbott Furnace Co., suggests that the right approach to AM with metals depends upon the ability of manufacturers to refine their application. “Manufacturers should not take the ‘shotgun’ approach of ‘I can print anything,’” comments Feldbauer. “Instead, they should focus on what makes the most sense for them and specialize in those parts rather than just printing something because it’s possible.

However, because it provides significant benefits, AM does have application in the several manufacturing sectors. Advantages in using AM to produce parts include minimization of waste, time and cost efficiency, and the ability to customize parts for single-use applications or low-volume production runs.

Thanks to these benefits, AM is currently being used in the following industries:

Aerospace: functional parts, such as engine turbine blades and fuel systems
Automotive: various components, such as suspension systems, engine parts, and door panels
Defense: obsolete parts, as well as vehicle and weapon components
Medical: implants, prosthetics, and other apparatuses

And, as AM technology continues to expand, it is becoming more widely accepted and is most notably being employed to create safety-critical aerospace and automobile parts. For example, General Motors (GM) announced that it is using AM-printed seatbelt pillar adjustable guide loops in its all-electric Cadillac Celestiq, making them GM’s first safety-related AM-printed metal part.

The component is made by Azoth using Markforged metal binder jetting technology with a liquid binding agent. Following the process, the metal parts are then sintered, polished, and plated. Automotive sector acceptance of additive manufactured safety-critical parts is a tremendous boon for the AM industry.

Experts like Feldbauer see the need for manufacturers to make a few key decisions for this technology to become a reality. “For additive manufacturing to be a commercially viable solution,” he argues, “manufacturers must determine which parts they can 3D print with high levels of success and where printing is cost effective and profitable. Commercial viability is really the determining factor as to whether a part should be 3D printed or made using conventional manufacturing techniques.”

Currently, though, AM seems to be benefiting smaller jobs. According to Feldbauer, AM usually makes the most sense for small runs where there is a need for customized tooling; in these cases, manufacturers run into too complex of shapes or simply to time or cost intensive.

The Future of AM

While AM is increasingly accepted as a beneficial process across many industries, it still faces challenges affecting its usage more broadly, such as material restrictions, bed or plate sizes for techniques that rely on bed printing, and the need to purchase high-end printers from a market that is constantly consolidating. Research and development into the process, more diversity in technologies, increased availability of AM outsourcing companies, and the benefits associated with cost, time, and material reductions are expected to be a driving force in widespread commercial adoption.

Stephen Feldbauer, director of Research and Development with Abbott Furnace Co., updated Heat Treat Today on the state of AM in 2025

As the technology continues to mature, AM will continue to expand into industries where the availability of high-volume AM production, such as is possible with binder jetting, would reduce the cost of part manufacturing. Additionally, optimizing post-process heat treatment methods will help further enhance the cost effectiveness of AM with metals and enable more customized characteristics. These advances could make AM an attractive and economical option for manufacturers, so those who want a competitive edge should begin to focus and refine application of AM to the parts for which it will be most worthwhile.

References

Grand View Research. 2022. Additive Manufacturing Market Size, Share & Trends Analysis Report by Component, by Printer Type, by Technology, by Software, by Application, by Vertical, by Material, by Region, and Segment Forecasts, 2024 – 2030. April 2022. Grandview Research. Report ID: GVR-4-68039-922-9. https://www.grandviewresearch.com/industry-analysis/additive-manufacturing-market#

Check out our AM/3D Trivia to test your knowledge of the AM/3D industry, the processes, and the technology.

This editorial was written by the Heat Treat Today Editorial Team.

Find heat treating products and services when you search on Heat Treat Buyers Guide.Com

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The Future Is Coming Three Times Faster Than You Think

July 29, 2025 / BURNERS & COMBUSTION SYSTEMS TECHNICAL CONTENT, GUEST COLUMN, MANUFACTURING HEAT TREAT TECH, OP-ED

In this Technical Tuesday installment featuring Combustion Corner by Jim Roberts, president of U.S. Ignition, readers are enlightened about how upcoming policies might impact their burner systems, fuel mixtures, and equipment. Could certain policies impact technical requirements of heat treating? Find out more below.

This informative piece was first released in Heat Treat Today’s July 2025 Super Brands print edition.

A furnace guy goes into a bar and says, “This looks like a fast crowd… and all the players nod in agreement.”

Where are we? It’s the future! And in heat treating and combustion circles, the changes that will occur in the next several years will be very impactful to our industry. We’ve all heard these things, and we have some of the very best experts in the world working for us in this industry to make sure that we continue to grow and to be a leader in the legislation and rules that could cripple the wonderful world of heat treating and metals.

We are lucky to have industry associates at the Metal Treating Institute (MTI) who understand the impact of some of these new regulations. In this year’s Air & Atmosphere issue of Heat Treat Today magazine, Michael Mouilleseaux (Erie Steel LTD) provided updates on the proposed decarbonization initiatives. I have seen presentations by Michael and his committee composed of Heather Falcone (Cook Induction Heating Company) and Ben Gasbarre (Gasbarre Thermal Pro c essing Systems). This is critical knowledge for us all, and we should be staying as vigilant and supportive as we can. Michael’s interview is a must-read in that February issue – if you missed it, go back and read it. Please.

And then you say, “What’s this got to do with combustion equipment and the stuff that this Roberts guy is normally talking about?”

Well, not only does the decarbonization mandate mean the possibility of costs through government burdens and penalties, but the equipment and process change requirements are going to be staggering if we don’t prepare.

As long as I’m in a name-dropping mood, I’m going to mention Brian Kelly of Honeywell. Brian is a degreed aerospace engineer, and yet he decided to come play in the mud with us furnace guys for a career. Brian has several detailed presentations online about some of the prime initiatives for all the combustion equipment companies — hydrogen Combustion. Yep, the “H” word. The holy grail of zero pollution. One of those presentations includes fascinating detailed data on hydrogen and other emission initiatives, given by Brian Kelly and Todd Ellerton on YouTube regarding future combustion technology requirements.

“So, what does the “three times faster” thing mean, Jim?”

Well, all major combustion equipment companies, like Honeywell, understand that hydrogen requires three times the amount of fuel to generate the same amount of available heat as natural gas. Hydrogen also burns with seven to eight times the “flame speed” of natural gas. It burns, on average, about 400 degrees hotter (F) than natural gas. And so, from an engineering standpoint, there are a fantastic number of variations that must be considered as we look forward, especially when addressing CO₂ and other emissions. Add propane, butane, methane, producer gas, landfill gas, and anything else that is presently being utilized in the heat treat circles, and that provides a lot of possible variations!

Now, it needs to be said that a good many burners can burn hydrogen already. The anticipation of this level of scientific and ecological requirements was seen a long time ago. Conversely, many cannot. Brian Kelly explains that 17% of the present pre-mix/blended fuel systems cannot utilize this fuel. It also bears mentioning that there are three different grades of hydrogen production levels.

So, let’s start doing the math on how many iterations it will take. But here is the biggest tidbit of hydrogen science in the combustion world – hydrogen is the smallest molecule and the lightest in a molecular sense. Helium is smaller and lighter, for fact-checker purposes, but we aren’t trying to burn helium, are we? So, as we blend hydrogen with our other fuels (i.e., the most practical way to maintain some of the infrastructure and equipment), we need to have our combination equipment suppliers test and verify that which exists will work.

Obviously, if it takes three times the fuel volume, existing gas delivery lines will be an issue. At the molecular level, smaller and lighter means that many existing seals, connections, and control valves may no longer be gas-tight and may leak. That’s not good! If the flame speed of these fuels is five to eight times that of existing fuels, temperature profiles within the process will need to be reviewed and re-calibrated. And if it burns 400 to 500 degrees hotter, certainly that will require a review of the former materials of construction.

So, how does this tie into the original theme of “The future is coming fast?” Well, we have just touched briefly on one possible fuel transition that is on the horizon. Carbon points/credits are already being taxed in Europe. We can bet that these global decarbonization efforts will be moving ahead. We will need a review so that a “head in the sand” mentality does not catch any of us in the thermal processing community flatfooted and ill-prepared.

It’s easy to think that it won’t affect you. When I mentioned “three times as fast,” of course, I was alluding to the fuel references, and the best way to be prepared for the future is to see it coming. Be alert and stay current, and we will adapt as an industry, as we have so many times before. Until next time …

About The Author:

Jim Roberts president at US Ignition, began his 45-year career in the burner and heat recovery industry focused on heat treating specifically in 1979. He worked for and helped start up WB Combustion in Hales Corners, Wisconsin. In 1985 he joined Eclipse Engineering in Rockford, IL, specializing in heat treating-related combustion equipment/burners. Inducted into the American Gas Association’s Hall of Flame for service in training gas company field managers, Jim is a former president of MTI and has contributed to countless seminars on fuel reduction and combustion-related practices.

For more information: Contact Jim Roberts at jim@usignition.com.

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From Furnace To Your Front Door: A Morning in Heat Treatment

July 8, 2025 / HARDENING TECHNICAL CONTENT, MANUFACTURING HEAT TREAT TECH, NITROCARBURIZING TECHNICAL CONTENT

Heat treatment impacts almost every facet of our lives, yet few people are aware of how important this practice is to a modern way of living. Heat treatment is a process which changes the microstructure of a metal, such as hardening, carburizing, tempering, and many others.

When a metal is formed, it undergoes heat treatment in order to make it longer lasting, change its structure so that it becomes harder or softer, or reduce the tendancy toward cracking which can form during manufacturing. To help us appreciate the impact of heat treatment on our daily lives, Tiffany Ward, daily editor for Heat Treat Today, has prepared this illustrative post.

Breakfast of Champions

You wake up in the morning and roll yourself out of bed, greeting a foggy sunrise through the window. You stumble to the kitchen to fire up your cast iron skillet.

Cast iron contains a minimum of 2% carbon

At one time, that same cast iron skillet lived a provincial life, known as simply: iron. Cast iron is made from iron with greater than 2% carbon, which is in the form of graphite. When that iron was “cast,” it was melted at a high temperature, and once cooled, it transformed into a very stable material that heats and cools uniformly. Perfect for your sunny-side-up eggs.

At the foundry, someone poured the molten metal into a mold to form the exact shape your pan is in today, and then it underwent numerous heat treat processes: annealing, normalizing, tempering, and even graphitizing (a process of converting carbon into graphite). The particular processes the skillet underwent depend upon the chemistry of the cast iron.

Almost all cast iron has carbon and nitrogen added to its surface in a process called ferritic nitrocarburizing plus post-oxidation. This heat treatment gives a shallow surface layer to the pan for better wear resistance. The skillet is heated up between around 1550°F and 1650°F inside a protective atmosphere of Endothermic gas. Endothermic gas is a generated heat treat atmosphere. It is made up of approximately 40% hydrogen, 40% nitrogen, and 20% carbon monoxide. The Endothermic gas is enriched with both a hydrocarbon gas (i.e., natural gas or propane) and ammonia so that carbon and nitrogen can be added to the iron.

There are a variety of different furnaces that can be used for ferritic nitrocarburizing. Box, pit, and tip-up furnaces are used due to their large capacity. For cast iron skillets, one common choice is the pit furnace — a cylindrical furnace typically located in the floor of a factory. Pit furnaces can hold a lot of heavyweight items, making them a good fit for the cookware now resting on your stove.

Figure Source: Herring, Daniel H., Atmosphere Heat Treatment Volume 1, BNP Media II, LLC, 2014.

Technical Resource: An Overview of Case Hardening: Which Is Best for Your Operations?

Technical Resource: Nitriding and Nitrocarburizing: The Benefits for Surface Treatment

It Cuts Like a Knife

You pull a knife out of your drawer and begin slicing an apple. The blade reflects a beam of sun from the window, but it isn’t your best knife. You’ve noticed that some of your knives are sharper and can resharpen more easily than others; this is because of the quality of the original material used and the heat treatment process employed in manufacturing the knife.

Perhaps the knife you chose to use today was made from high carbon steel such as 1095. The blade was heat treated using a process of hardening, quenching, and tempering. After the blade was formed, it entered a continuous mesh-belt furnace and was quenched in either oil (in the case of a 1095 steel), or in the case of stainless steel or tool steel, cooled in still air.

Source: Dan Herring, The HERRING GROUP, Inc.

Figure: Batch integral-quench furnace system installation (courtesy of AFC-Holcroft). Dan Herring, The HERRING GROUP, Inc.

At the same time of hardening and quenching, the handle was joined to the blade in a process called brazing. The entire knife was heated up to an austenitizing temperature and rapidly cooled in the quenching process, giving it a particular hardness level.

The hardening process can be performed in a vacuum furnace or an atmosphere furnace. The atmosphere is typically nitrogen or, more commonly, a nitrogen/hydrogen mixture. Another option is nitrogen plus dissociated ammonia (dissociated ammonia is 75% hydrogen, 25% nitrogen).

A typical temperature for the heat treatment of high carbon 1095 steel knives is 1475ºF. Stainless steels are run at higher temperatures, typically in the range of 1800º/1950ºF and tool steels even higher, to around 2200ºF.

Technical resources: Ask the Heat Treat Doctor®: How Does One Determine Which Quench Medium To Use?

Technical Resource: Heat Treat Radio #105: Lunch and Learn: Batch IQ Vs. Continuous Pusher, Part 2

Time to Look Pretty

After breakfast you head to the bathroom. You are anxious to rid yourself of unshaven scruff, carefully running a razor over your face. The razor blades were hardened and tempered for sharpness, so that you get a smooth, clean shave.

Like knives, razor blades are hardened and are made of a medium to high carbon steel. Unlike knives, they are hardened in a continuous strip form. Envision all of your razor blades as a single, thin strip, run continuously through a furnace to heat and cool them. The blade is heated in a protective atmosphere as it runs through the furnace. On one end of the furnace is a reel that coils the strip and at the other end is an un-coiler.

Continuous style furnaces have alloy tubes inside of them that are very small in diameter, typically one inch, which run the entire length of the furnace. As the razor strip is run through the tube it is exposed to an atmosphere of nitrogen and hydrogen, typically with 3% hydrogen, to protect the razor blade surface from oxidation. Once heated, the blade enters cooling either by surrounding the tube with water or by blowing forced air on the tubes.

A process called tempering follows hardening and quenching. When you harden a material you make it stronger, but less ductile, so there is a concern that the razor blade might break. The tempering process improves ductility, removing some of the hardness but improving flexibility.

Dan Herring, The Heat Treat Doctor^®, describes the balancing act this way: “On one end of the teeter totter, metallurgically, are strength properties and on the other side of the teeter-totter are ductility properties. It’s always a challenge to properly balance the teeter-totter. If you get the hardness too high, what happens to the ductility? It’s very low. As a result, the material is super hard but may crack easier. On the other hand, if ductility is too high, the material is super flexible so that it can bend like a branch of a tree in the wind, but it has little strength. You need a balance of strength and ductility in all heat treated products, which is accomplished in part by proper tempering.”

Technical Resources: Tempering: 4 Perspectives — Which makes sense for you?

Technical Resources: Ask The Heat Treat Doctor®: What Are the Differences Between Intergranular Oxidation (IGO) and Intergranular Attack (IGA)?

Wake Up and Smell The Heat treatment

Our lives are touched by heat treatment at every turn. Highly technical processes play their role in the formation of even the most common household items. While heat treatment may seem to some a niche industry, its impact on everyday life is ubiquitous.

A special note of thanks to Dan Herring, The Heat Treat Doctor^®, for his insights and contributions which informed this post.

Find heat treating products and services when you search on Heat Treat Buyers Guide.Com

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AM/3D Trivia

February 4, 2025 / MANUFACTURING HEAT TREAT TECH, SINTERING POWDER/METAL TECHNICAL CONTENT, TECHNOLOGY

In today’s Technical Tuesday installment, we highlight the various techniques and developments in the world of metal AM as it pertains to post-process heat treating. Check out the trivia quiz below to test your knowledge of the AM/3D industry, the processes, and the technology.

This feature was first released in Heat Treat Today’s January 2025 Technologies To Watch in Heat Treating print edition.

Additive manufacturing (AM), commonly known as 3D printing, has a history marked by constant innovation for uses across the space, aerospace, medical, food, and manufacturing industries, to name a few. While AM is known to support, streamline, and customize part production, advanced materials paired with evolving AM techniques are creating new possibilities in materials engineering and industrial manufacturing. Due to the nature of this ever-developing technology, in-house heat treaters must continually learn about AM components and how thermal processing may enhance component properties.

What was the original name for additive manufacturing (AM), circa 1980s?
A) 3D printing
B) Rapid prototyping (RP)
C) Additive manufacturing (AM)
D) Rapid tooling (RT)
What grade of stainless steel is most commonly used for AM to achieve varying levels of strength, hardness, and elongation when heat treated?
A) 17-4 PH
B) 316L
C) 304
D) 430
Who is Emanuel “Ely” M. Sachs?
A) An engineer at GE Aviation who combined multiple parts into one huge, complex design using a laser-based additive manufacturing method called direct metal laser melting
B) An engineer at Stratasys Ltd., an American-Israeli manufacturer that began using a material extrusion based process with their FFF (fused filament fabrication) technology to print parts, patented in 1989
C) A professor of Mechanical and Materials Engineering at Worchester Polytechnic Institute who evaluated the post process heat treating of DMLS titanium alloy parts
D) An MIT engineering professor who patented the process of metal binder jetting technique in 1993
What do cast parts made from powder metallurgy methods and AM parts have in common?
A) The same heat treatment cycles produce the best results
B) Custom cycles are used in less than 2% of both applications
C) Parts exhibit porosity
D) None of the above
What are the most commonly adjusted parameters to achieve higher yield strength when heat treating AM parts?
A) Cooling and heating rate
B) Temperature and time
C) Time and pressure
D) Temperature and pressure
Why is HIP known as the “gold standard” for processing AM parts for space?
A) Eliminates porous microstructures without compromising the part’s geometries and dimensions
B) High level of control and uniformity
C) Combines high temperature and pressure to improve a part’s mechanical properties
D) All of the above
What is NOT a potential benefit of additive manufacturing?
A) Immediate cost savings
B) Fast part production
C) Rapid prototyping
D) Opportunity for increased automation and use of robotics
What are the two main categories for most 3D printing methods?
A) Those that use liquid binding polymers, and those that don’t
B) Binder jetting technology (a non-melt-based process) and melt-based processes
C) Both A and B
D) Neither A nor B
Which alloy was originally developed for aerospace applications but became one of the most common biomedical alloys?
A) Inconel 718
B) Inconel 625
C) Ti-6Al-4V
D) Hastelloy C22
What was the first rapid prototyping method to produce metal parts in a single process (and is one of the most widely used AM technologies to manufacture Ti-6Al-4V parts)?
A) Powder-bed fusion (PBF)
B) Directed energy deposition (DED)
C) Sheet lamination (SL)
D) Direct metal laser sintering (DMLS)
In what way does high temperature processing — specifically HIP below the annealing temperature (1470°F/799°C) — improve DMLS Ti-6Al-4V parts?
A) Preserves surface roughness and enhances osteointegration
B) Reduces porosity and enhances corrosion resistance
C) Both A and B
D) Neither A nor B
What is the ideal way to process 3D printed parts made using liquid binder polymers?
A) Print the parts in-house followed by debind and sinter.
B) Have AM parts delivered in-house for heat treating when parts are at the “Green” stage
C) Have AM parts delivered in-house for heat treating when parts are at the “Brown” stage
D) None of the above

How Did You Do?

Click here for answers.

We would like to thank Dan Herring, Animesh Bose, Ryan Van Dyke, Rob Simons, and Phil Harris for contributing their expertise to this trivia feature.

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Experts Anticipate Key Heat Treat Technology Adoptions

January 28, 2025 / MANUFACTURING HEAT TREAT TECH, TECHNOLOGY

Industry experts agree: 2025 is a year of significant, high-tech developments. In this Technical Tuesday, hear from three heat treat industry consultants on current and incoming technological advances, from miniaturization and customization to artificial intelligence.

Michael Mouilleseaux, general manager at Erie Steel, Ltd, opens the discussion by asking what role AI has in a perfect world of heat treating; Thomas Wingens, president of Wingens Consultants, predicts six major technologies to look for in 2025; and Dan Herring, a.k.a. The Heat Treat Doctor® and owner of The HERRING GROUP, Inc., points out how the trend toward smaller is affecting the heat treat industry.

This informative piece was first released in Heat Treat Today’s January 2025 Technologies To Watch in Heat Treating print edition.

AI’s Place in Heat Treating?

by Michael Mouilleseaux

The benefits of AI are purported to be the ability to reduce the time required to complete complex tasks, such as data analysis, while reducing human error and providing both unbiased decision making and data-driven system enhancements … and by the way, it can operate 24/7 without breaks!

Does AI have a place in heat treating?

Here’s what I would want my heat treat AI (HT AI) to be able to do with a gas-fired atmosphere furnace.

Combustion System:

My HT AI will continuously monitor the free oxygen of all the burners and keep them at a perfect ratio, thereby optimizing performance and gas consumption. It will track these changes and provide analysis of any trends that it “perceives,” so to speak.
My HT AI will continuously monitor combustion air pressure and message me in time to have the air filters changed before it affects performance. It will track this and provide historical and prescriptive information.
My HT AI will periodically perform a “tube check,” whereby it will shut off combustion in a tube and monitor the free oxygen, recognizing that any diminishment from “atmospheric” O2 levels indicate the potential of a tube leak. It will track this and provide analysis of any trends that it perceives.
My HT AI will track when system thermal stasis is achieved, monitor gas consumption for each discrete heat treat cycle, provide analysis of trends that it perceives, and recommend thermal cycle changes to optimize these cycles.

My HT AI will facilitate the optimization of the critical human assets in process engineering, product quality and equipment maintenance.”
Michael Mouilleseaux

Atmosphere Control System:

My HT AI will continuously monitor the atmosphere flows required to achieve the requirements for each heat treat cycle. It will track “atmosphere recovery” and provide analysis of any trends that it perceives (i.e., increased usage as a precursor to a furnace leak).
My HT AI will periodically perform a furnace check, whereby it compares the composition of the Endo gas in the furnace to that exiting the generator, providing a measure of furnace integrity. It will track this and provide analysis of any trends that it perceives.
My HT AI will confirm “tube check” data (see above) with atmosphere usage to evaluate its potential effects on process integrity and make actionable recommendations. It will track these incidents and provide analysis of any trends that it perceives.
My HT AI will provide assurance of system performance and actionable information.

Shoot for the Moon:

My HT AI will have the unique ability to integrate metallurgical results with process information and thereby provide the ability to optimize the heat treating process AND metallurgical results.
My HT AI will allow me to input material chemical and hardenability data and, by comparing actual results with the calculated, or prospective results, provide confirmation of the thermal and quenching segments of the process.
My HT AI will be able to correlate IGO results with furnace integrity checks (i.e., leaks) and over time establish hard limits for allowable leak rates.
My HT AI will be able to correlate actual retained austenite levels in carburized case with furnace carbon potential and make data-driven process modifications to optimize this.
My HT AI will be able to correlate the shape of the case depth curve with the carburizing cycle and the material type, and it will make data-driven process modifications to optimize this.
My HT AI will have the ability to develop new heat treat thermal cycles specific to my furnaces extrapolated from existing data.

My HT AI will provide a level of system performance heretofore not achieved, that not only assures adherence to established standards but provides a clear path of continuous improvement via data analysis and actionable actions. Product results will be validated by total process control, and total process control will assure attainment of product results.

My HT AI will facilitate the optimization of the critical human assets in process engineering, product quality and equipment maintenance.

In short, my HT AI will afford the heat treating community the ability to finally jettison the mantle of “black art” and join the community of high-tech engineered processes.

About the Author:

Michael Mouilleseaux
General Manager
Erie Steel, Ltd

Michael Mouilleseaux has been at Erie Steel in Toledo, OH, since 2006 with previous metallurgical experience at New Process Gear in Syracuse, NY, and as the director of Technology in Marketing at FPM Heat Treating LLC in Elk Grove, IL. Having graduated from the University of Michigan with a degree in Metallurgical Engineering, Michael has proved his expertise in the field of heat treat, co-presenting at the 2019 Heat Treat show and currently serving on the Board of Trustees at the Metal Treating Institute.

For more information: Contact Michael at mmouilleseaux@erie.com.

Future Outlook for 2025

by Thomas Wingens

2025 will be the year of invention and application. There are six major technologies to be looking out for: AI management software, giga casting for the EV industry, high-pressure quench furnaces, thermal processing specialty materials, processing for steel enrichment, and practices for cleaning consistency.

AI Management Software

Some new heat treat shop management software is now available. It utilizes artificial intelligence to save labor while documenting all processes in real time. The software easily adapts to the way we work and is much easier to learn and implement than the software of the past. I see this as the number one investment item for commercial heat treaters in 2025, as it is the cheapest and easiest way to automate with a great ROI while increasing quality and customer service.

Giga Casting

With Tesla as the main driver, very large so-called “GIGA” H13 aluminum dies of 3 to 8-ton weight have really taken off in the last years, in particular for new electric car models, and the demand for very high pressure quench furnaces is increasing in the U.S. (more to come in a later article).

Vacuum Oil Quenching

However, even with the most advanced designs and high-pressure efforts, gas quenching with nitrogen has its limits, and the use of helium is not considered anymore because of its immense cost, even with a recycling system in place. Vacuum oil quenching has become a viable alternative in recent years not only in combination with LPC (low-pressure carburizing) but also with the use of materials like AISI 52100 that would be typically heat treated in atmosphere integral quench furnaces but show lesser distortion with the variation of pressures over the oil bath, which can shift the oil boiling phase peak to lower temperatures (e.g., from 650°C (1200°F) at atmospheric pressure to 400°C (750°F) at 1 mbar pressure). Some new modern vacuum oil quench furnace designs have recently entered the market, showing excellent surface cleanliness and distortion results. Aside from the better quality, they offer a much safer, cleaner and more pleasant work environment.

Specialty Materials

In general, we see a higher demand for the thermal processing of specialty materials; for example this is seen with the hydrogen decrepitation of titanium, tantalum, niobium, or rare earth element materials, powder processing or sinter processes, and surface diffusion processes.

Steel Enrichment

Enriching stainless steel with nitrogen is not new, but it is gaining momentum and more applications. One method for\ low-temperature processes on austenitic stainless steels around 370°C (690°F) is called S-phase case hardening, and the high temperature version around 1100°C (2010°F) is called solution nitriding. Both processes were initially established in the early 90s in Europe but seem to be gaining momentum and more comprehensive applications worldwide over the last years.

Figure 1. For 2025, “We see more fully enclosed vacuum solvent cleaning in heat treat shops to ensure a higher standard and consistency of the surface cleaning results compared to the fading of water cleaners.” – Thomas Wingens, WINGENS CONSULTANTS

Cleaning Consistency

Speaking of surface processes: The cleaning of components has been a thankless process, especially in commercial heat treatment, as it is seen as a necessity that is not necessarily paid for by the clients but is necessary to have uniform dissociation on the surface of a part to ensure a uniform case (e.g., nitriding case). There are well-defined standards for temperature uniformity and hardness testing, but cleaning consistency needs to be addressed, as it can be very impactful. We see more fully enclosed vacuum solvent cleaning in heat treat shops to ensure a higher standard and consistency of the surface cleaning results compared to the fading of water cleaners.

About the Author:

Thomas Wingens
President
WINGENS CONSULTANTS

Thomas Wingens has been an independent consultant to the heat treat industry for nearly 15 years and has been involved in the heat treat industry for over 35 years. Throughout his career, he has held various positions, including business developer, management, and executive roles for companies in Europe and the United States, including Bodycote, Ipsen, SECO/WARWICK, Tenova, and IHI-Group.

For more information: Contact Thomas at www.wingens.com.

Miniaturization and the Heat Treat Industry

by Dan Herring

Everywhere we turn today, the products we use are getting smaller, more compact and more powerful. This is true across all industries, from aerospace to automotive, from medical to electronics, and from energy to semiconductors to name a few. Today, miniaturization, portability and customization have become major design objectives for almost all manufacturing segments.

These trends are irreversible and are, or will be, found even in the most unlikely of places — both in mining of resources taking place deep under the ocean floor and eventually on other planets. The key question then becomes, how will all of this influence our heat treating operations?

Miniaturization, Portability and Customization Today

Given the ever-increasing demand for higher performance in a smaller footprint, we have often focused our energies on taking existing products and adapting them for use. But in the long term, this is not sustainable. For example, not only is gear noise reduction critical in our submarines, but the medical and robotics markets are continuously searching for smaller, more efficient, more application specific and more intelligent drive systems and motors with increased torque density.

Heat treatment will experience a metamorphosis and emerge more broadly as thermal treatment. The age of metals as we have known it has become the age of materials: ceramics, composites, powder materials, glasses, polymers, fiber-reinforced plastics, and even nanomaterials.
Dan Herring, The Heat Treat Doctor®

Another example, although not new, is miniaturization in vehicle electronics, especially as it relates to data collection where demand is high for smaller, more powerful and, yes, cheaper components. Integration into the electronic control units via on-board power systems has seen the need for more cables in vehicles and positioning connectors, which means more contacts/connections on the electronic components without significantly increasing the installation space.

Similarly, there is a huge demand for portability. This is true not only in our electronics (just think about how cell phones or computers have changed over the last ten years), but there is a growing need for portable medical devices so that medical care can be brought to the patient rather than the other way around. For example, longer battery life and lighter weight are critical for devices such as portable oxygen concentrators.

What Does This Mean for the Heat Treatment Industry?

Looking ahead, we will see both short and long-term changes to our industry. Happening today and continuing in the near term, heat treaters are working closer than ever with design and manufacturing engineers as they focus on products that reduce environmental impact, are produced at lower unit cost, and with improved part quality. Still, the era of mass recalls must come to an end. And the cost of heat treating is less than it was even a decade ago. But as manufacturing demand evolves due to consumer expectation, process and equipment flexibility will become keys to meeting the highest quality standards in an on-demand world.

Historically, changes in the heat treat industry has been evolutionary and incremental in both nature and effect. There have been notable exceptions such as the invention of the oxygen probe or low pressure vacuum carburizing. But to meet the manufacturing demands of the future, change will need to be more revolutionary and abrupt in nature, a game changer.

Given the ever-increasing demand for higher performance in a smaller footprint, we have often focused our energies on taking existing products and adapting them for use. But in the long term, this is not sustainable. For example, not only is gear noise reduction critical in our submarines, but the medical and robotics markets are continuously searching for smaller, more efficient, more application specific and more-intelligent drive systems and motors with increased torque density.
Dan Herring,
The HERRING GROUP, Inc.

Heat treatment will experience a metamorphosis and emerge more broadly as thermal treatment. The age of metals as we have known it has become the age of materials: ceramics, composites, powder materials, glasses, polymers, fiber-reinforced plastics, and even nanomaterials. As a result, we will find ourselves needing, for example, to expand our heat treat capability and equipment to deal with such items as process temperature ranges from -200°C to 1850°C (-330°F to 3360°F) or greater or at pressure/vacuum levels heretofore only achievable in laboratories or specialty applications.

As product sizes decrease, load sizes will become smaller out of necessity. And as a result, our heat treat equipment must be small lot capable with tighter controls to achieve higher quality along with tremendous process flexibility.

Final Thoughts

History’s enduring legacy is that change is inevitable. Just think back to how the heat treatment industry has evolved, from the campfire to the blacksmith to the modern heat treater, from the artisan to the era of mass production, from the art of heat treating to the science of heat treatment. The lesson is that to adapt, one must constantly innovate and invent. Miniaturization, portability and customization in whatever form they take are here to stay. Perhaps even teleportation (the ultimate miniaturization?) isn’t that far off after all, considering flight was unheard of a little over a century ago.

About the Author:

Dan Herring
(The Heat Treat Doctor®)
The HERRING GROUP, Inc.

Dan Herring has been in the industry for over 50 years and has gained vast experience in fields that include materials science, engineering, metallurgy, new product research, and many other areas. He is the author of six books and over 700 technical articles.

For more information: Contact Dan at herring@heat-treat-doctor.com.

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Ask the Heat Treat Doctor®: What Does “Bright and Shiny” Really Mean?

December 3, 2024 / INSTRUMENTATION TECHNICAL CONTENT, MANUFACTURING HEAT TREAT TECH

The Heat Treat Doctor® has returned to offer sage advice to Heat Treat Today readers and to answer your questions about heat treating, brazing, sintering, and other types of thermal treatments as well as questions on metallurgy, equipment, and process-related issues.

Clients often want to know or specify that their component part surfaces are “bright” or “shiny” or “clean.” Other times they desire to have a surface condition that is “scale free” or “oxide free” after heat treatment. But how, if at all, can we quantify what these terms mean? Let’s learn more.

“Shiny” and “bright” are words that are highly subjective. This is often a source of confusion not only for the heat treater, but the manufacturer and, in some cases, even the end user of the products. Heretofore, the answer depended on one human being’s interpretation as opposed to another, and evaluations depend not only on the type of material but also the mill practices used, manufacturing methods employed, heat treatment processes, and the level and type of contamination introduced before and after processing.

Traditional Approach

Figure 1. Temper color chart atmosphere or tempering in air or an “inert” gas such as nitrogen. Source: Abbott Furnace Company

Traditionally, we have relied on color charts (Figure 1) to tell the approximate temperature at which discoloration took place, that is, an oxide formed on the (steel, stainless steel, or tool steel) surface of a component part. This method is still in use today when cooling parts in a furnace

As mentioned, the perception and interpretation of color is different for different people. Lighting (natural light or plant illumination), the environment in which one views color, eye fatigue, the age of the observer, and a host of other factors influences color perception. But even without such physical considerations, each of us interprets color based on personal perception. Each person also verbally describes an object’s color differently. As a result, objectively communicating a particular color to another person without using some type of standard is difficult.

There also must be a way to compare one color to the next with accuracy.

New Approach

Today, portable spectrophotometers (Figure 2) are available to measure color and help quantify brightness measurements. These types of devices are designed to meet various industry standards including:

Whiteness (e.g., ASTM E313, CIE)
Gray scale (e.g., ISO 105 staining, color change)
Opacity (e.g., contrast ratio, Tappi strength — SWL, Summed, Weighted Sum)
Yellowness (e.g., ASTM E313, D1925)

Figure 2. X-Rite MA-5 QC multi-angle spectrophotometer. Source: X-Rite

In simplest terms, a spectrophotometer is a color measurement device used to capture and evaluate color. Every object has its own reflectance, or the amount of light it reflects, and transmittance, or the amount of light it absorbs. A reflectance spectrophotometer shines a beam of light and measures the amount of light reflected from different wavelengths of the visible spectrum, while a transmission spectrophotometer measures how much light passes through the sample. Spectrophotometers can measure and provide quantitative analysis for just about anything, including solids, liquids, plastics, paper, metal, fabric, and even painted samples to verify color and consistency.

Spectrophotometers provide the solution to the subjective problem of interpreting the color of the surface of a component part that has been heat treated, brazed, or sintered because they explicitly identify the colors being measured; that is, the instrument differentiates one color from another and assigns each a numeric value.

As an example, the brightness of steel tubes annealed in a rich Exothermic gas atmosphere was measured against tubes that had not been processed (Figure 3). Having this definite measurement of the surface changes allowed the heat treater to provide their client with a definitive statement on the change after processing.

CIE Color Systems

The Commission Internationale de l’Eclairage (CIE) is an organization responsible for international recommendations for photometry and colorimetry. The CIE standardized color order systems include specifying the light source (illumination), the observer, and the methodology used to derive values for describing color, regardless of industry or use case.

Though spectrophotometers are the most common, for some applications colorimeters can also be used, but these are in general less accurate and less suitable for a heat treat environment.

There are three primary types of spectrophotometers on the market today used for print, packaging, and industrial applications: traditional 0°/45° (or 45°/0°) spectrophotometers, primarily used for the print industry; sphere (or diffuse/8°) spectrophotometers, primarily used in the packaging industry; and multi-angle (MA) spectrophotometers, for use in industrial environments. These instruments capture color information, and in some cases can capture appearance data (e.g., gloss).

Multi-angle (MA) spectrophotometers are best suited for measurements involving special surface effects, such as those found on metal surfaces and coatings and include those with surface contaminants and even can quantify cosmetic appearance. These are typically used on the shop floor, in the lab and in quality control, and even can be found in shipping areas.

MA spectrophotometers require users to verify five or more sets of L*a*b values or delta these terms). They typically have an aperture size of 12 mm, which is too large for measuring the fine detail that occurs in many small-scale industrial applications. Primary illumination is provided at a 45° angle. Some models have secondary illumination at a 15° angle.

Figure 3. Example of a product test — color and oxidation level test. Source: X-RIte

An application example for an MA spec trophotometer lies in their use for collecting colorimetric data on special effects coatings in the automotive industry, capturing reliable color data in cases where special effect coatings are used.

Final Thoughts

In this writer’s opinion, a spectrophotometer should be in every heat treat shop! You will be doing both yourself and your customers a valuable service and take the guesswork out of one of the most commonly asked questions – is it bright?

References

Herring, Dan H. Atmosphere Heat Treatment Volume 1. BNP Media, 2014.
X-Rite Pantone. “A Guide to Understanding Color.” Accessed October 10, 2024. https://www.xrite.com/learning-color-education/whitepapers/a-guide-to-understanding-color.
X-Rite Panatone. “Tolerancing Part 3: Color Space vs. Color Tolerance.” Accessed October 10, 2024. https://www.xrite.com/blog/tolerancingpart-3.
X-Rite Pantone. “X-Rite Portable Multi Angle Spectrophotometers.” Accessed October 10, 2024. https://www.xrite.com/categories/portable-pectrophotometers/ma-family.

About the Author

Dan Herring has been in the industry for over 50 years and has gained vast experience in fields that include materials science, engineering, metallurgy, new product research, and many other areas. He is the author of six books and over 700 technical articles.

For more information: Contact Dan at dherring@heat-treat-doctor.com.

For more information about Dan’s books: see his page at the Heat Treat Store.

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Anatomy of a Front-Loading Vacuum Furnace

November 26, 2024 / MANUFACTURING HEAT TREAT TECH, VACUUM FURNACES TECHNICAL CONTENT

How well do you know the “anatomy” of your key heat treat equipment? In this “Anatomy of . . .” series, industry experts indicate the main features of a specific heat treat system. In this installment, the full-page spread identifies main features of a front-loading vacuum furnace.

The mark-ups for these reference images are provided by Jim Grann, technical director, Ipsen.

View the full graphics by clicking the image below.

This Technical Tuesday article is drawn from Heat Treat Today’s November 2024 Vacuum print edition with a special focus on vacuum furnace technologies.

Search www.heattreatbuyersguide.com for a list of vacuum furnace providers to the North American market. If you are a vacuum furnace supplier and are not listed here, please let us know at editor@heattreattoday.com.

This series will continue in subsequent editions of Heat Treat Today’s print publications. Stay tuned!

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Evolving Efficiency: Advantages of Multi-Chamber Isolated Heat Vacuum Furnaces

November 12, 2024 / MANUFACTURING HEAT TREAT TECH, VACUUM FURNACES TECHNICAL CONTENT

Adapting to new processing demands puts traditional equipment to the test. Can single-chamber solutions keep up, or will applications require different equipment options for efficient processing? In today’s Technical Tuesday, Bryan Stern, product development manager at Gasbarre Thermal Processing Systems, addresses the advantages multi-chamber isolated heat vacuum furnaces bring to the floor.

This informative piece was first released in Heat Treat Today’s November 2024 Vacuum print edition.

Do You Hear That? It’s the Sound of Change . . .

In the evolving landscape of vacuum heat treatment, single-chamber batch furnaces have long been the cornerstone of material processing. However, with more traditional processes shifting to vacuum, rising energy costs, and increasing environmental pressure, the disadvantages of that approach are emphasized, enhancing the appeal of alternative technologies. Multi-chamber vacuum equipment, while not new to the industry, offers significant solutions to inefficiencies and challenges faced by single-chamber systems. With advances in technology, improved operational planning, and an increasingly competitive market, multi-chamber isolated heat furnaces are becoming a more viable choice.

What Is an Isolated Heat Vacuum Furnace?

An isolated heat vacuum furnace keeps the heat chamber separate from the ambient atmosphere throughout the process, including loading and unloading. This allows the heated zone to maintain a stable temperature and vacuum between cycles, unlike single-chamber furnaces, which must heat up and cool down for each new load. Key components of this furnace type include an additional evacuation chamber, a dynamic sealing door, and a mechanism for moving the workload between chambers. While multi-chamber isolated heat furnaces may be batch or continuous, the above features fundamentally distinguish them from single-chamber batch equipment. This difference is more than just a technical nuance; it has profound implications for operations and efficiency.

The widespread use of single-chamber vacuum furnaces has significantly shaped the design and operation of vacuum furnaces today. But it is important to remember some of the challenges to this approach that we often take for granted.

Energy Efficiency Has Entered the Chat

Single-Chamber Challenge

In single-chamber systems, the entire furnace must go through a full cycle of loading, evacuation, ramping, soaking, cooling, and unloading for every batch of parts. This adds significant “dead time” on either side of the thermal process. In addition to pump-down time, ramping from room temperature typically adds 1–2 hours to the cycle time before soaking which creates a barrier to throughput. Another drawback is that the energy required to heat the furnace is thrown away after every cycle. Due to the high thermal capacity of materials like graphite and molybdenum, this is not inconsequential. With 100% thermal efficiency defined as only consuming the energy required to heat the work and fixturing, single-chamber batch furnaces typically operate in a thermal efficiency range of around 30%–50%.

Isolated Heat Advantage

In an isolated heat furnace, the work zone remains at temperature and the energy required to heat the furnace is not thrown away. Additionally, the introduction of work to a preheated work zone allows the load to be heated more quickly, reducing the time required to achieve temperature and reducing holding losses. While multi-chamber batch furnaces experience some savings, they still consume excess energy since the heat cage is empty during unloading, loading, and evacuation. Continuous configurations, however, see significant improvement with only holding losses and the energy required to heat the work and fixturing being consumed. These advantages mean that continuous furnaces typically operate in a thermal efficiency range of 45%–65%. The result is a 15%–35% energy efficiency improvement over the majority of existing equipment.

Figure 1. Single-chamber batch gas-quench furnace
Source: Gasbarre Thermal Processing Systems

Design Optimization: Do I Detect Some Tension?

Single-Chamber Challenge

The tension of designing a single-chamber furnace to handle both heating and cooling in the same space presents substantial challenges. Insulation pack thickness is often limited to balance the need for quick pump-down. Gas nozzle penetrations through the insulation pack create direct radiation losses. This erodes thermal efficiency, adds thermal mass, and restricts gas flow during cooling. These conflicting design priorities often lead to unsatisfactory compromises and fluctuating designs. Between the additional energy to heat and cool and increase power demand at temperature, there are a lot of energy savings being left on the table.

Isolated Heat Advantage

Because the heating and cooling take place in separate locations, multi-chamber isolated heat equipment benefits from the ability to have dedicated designs tailored at each work position. More insulation can be used as conditioning time is not a significant consideration. Additionally, the insulation can be designed without penetrations, further reducing losses. Moving the work to a dedicated cooling position removes restrictions to gas flow and allows the work to radiate directly to the cold wall. This is especially beneficial at the beginning of a quench when the work is at high temperature. This can allow cooling rates to be achieved with lower quench pressures and smaller quench motors.

Thermal Cycling: Here We Go Again . . .

Single-Chamber Challenge

A single-chamber furnace must be built to endure extreme thermal cycling again . . . and again. This requires detailed design consideration to account for thermal shock, expansion, ratcheting, creep, and low-grade oxidation — all of which contribute to maintenance and replacement cost for expensive, long lead refractory components.

Isolated Heat Advantage

Since the heated portion of the furnace remains at stable temperature and vacuum, internal components are not subject to the same destructive forces. An isolated heat cage can remain in service much longer before requiring service or replacement. It also decreases the likelihood of sudden and unexpected equipment failure. Increasing the lifespan of the most expensive consumable assembly in the furnace is an incredibly valuable advantage that is frequently overlooked.

rectangular promo of HTR, smiling bearded man, blue background, HTR banner — Find more on this topic in Heat Treat Radio episode #110. Bryan discusses the shift from single-chamber batch furnaces to isolated heat vacuum furnaces and speaks to some of the advantages mentioned in this article. Click the image to watch, listen, and learn on Heat Treat Radio.

Throughput and Load Size: Can They Help?

Single-Chamber Challenge

Single-chamber batch vacuum processing is notorious for the long cycle times and resulting limited throughput. One way to reduce the costs of the wasted energy and dead time is to increase the load size to distribute the cost over more work. While this can increase capacity and reduce the cost per part, it is counterproductive to many objectives of the heat treating process. As the load size increases, it becomes more difficult to maintain thermal and process uniformity across parts at the surface versus the center of the load. This is especially problematic for densely packed loads. Loads take longer to soak out to a uniform temperature, extending cycle times. Similarly, it is difficult to achieve rapid and uniform cooling rates which can lead to higher quench pressures, larger cooling motors, or underutilizing the work envelope.

Isolated Heat Advantage

While multi-chamber batch isolated heat furnaces experience many of the other advantages discussed in this article, throughput is where continuous configurations really shine. Because separate loads are being processed simultaneously, similar or greater throughputs can be achieved with much smaller load sizes. For instance, a process with a two-hour soak would typically require around a five-hour total cycle time in a single-chamber furnace. That same process could be segmented in a continuous furnace indexing loads in as little as 15 minutes, depending on the configuration of the equipment (see Figure 3). With a throughput ratio of 20:1, each load would only need to be 1/20^th of the batch load to achieve the same throughput. With these mechanics, it quickly becomes apparent how continuous processing is capable of achieving much greater throughput while benefiting from the uniformity of smaller load sizes as well as the other advantages discussed.

Figure 3. Multi-chamber continuous gas-quench furnace
Source: Gasbarre Thermal Processing Systems

Scalability: And Another and Another . . .

Single-Chamber Challenge

Increasing the capacity of a single-chamber production line necessitates adding additional discrete furnaces. This means that all of the equipment systems are duplicated. Each furnace means another chamber, pumping system, manifolds, quench motor, VFD, control cabinet, certifications, instrument calibrations, etc. There really is no economy of scale available to help facilitate high volume production.

Isolated Heat Advantage

For most processes, increasing the capacity of a continuous multi-chamber furnace only requires adding additional heated work positions to shorten the index rate. All other auxiliary equipment and infrastructure can serve double-duty, and redundant systems and maintenance are avoided. This applies the cost directly to the necessary equipment (heat cage, elements, power supply, etc.). The resulting economy of scale often makes continuous equipment a far greater value proposition for high-volume applications that would otherwise require multiple furnaces.

Vacuum Performance: Don’t Reduce Me Like That!

Single-Chamber Challenge

Because single-chamber batch furnaces are exposed to air and humidity between each cycle, they require a higher vacuum (i.e., lower pressure) to achieve the purity required for a given process. This is because even though the furnace is evacuated to a low pressure, the remaining atmosphere is still primarily comprised of oxidizers in the form of residual air and water molecules desorbing from the internal surfaces of the furnace. Achieving the high vacuum levels required to achieve the necessary reducing atmosphere in a reasonable time can result in additional pumping equipment such as a booster or diffusion pump. This adds to system complexity, upfront cost, maintenance, and operating cost. Unfortunately, vacuum processes are often developed in, and organized around, single-chamber batch processing, so the actual purity requirement often gets distilled into an ultra-low vacuum level on the process specification. Consequently, these aggressive vacuum specifications are carried over to other types of equipment where they may not be necessary to achieve the same results.

Isolated Heat Advantage

Because the heat cage remains under vacuum throughout the process, there is less exposure to atmospheric contaminants. This allows oxidizing constituents to decay to very low levels leading to improved vacuum purity. Even though the absolute pressure is higher, the makeup of the remaining atmosphere is primarily inert. Given time for desorption to decay, it is entirely possible to have a purer environment at a higher pressure without requiring the complex pumping systems necessary in a single-chamber batch furnace. Reduction levels associated with diffusion pumping in single-chamber furnaces can be achieved at higher pressures with a two-stage or even single-stage pumping systems in an isolated heat furnace. This is one of the most overlooked and misunderstood advantages of isolated heat processing.

The Shift Toward Isolated Heat Furnaces

Despite the many challenges associated with single-chamber batch processing, the prevalence of these furnaces has remained high due to their simplicity and familiarity. So, why are multi-chamber furnaces gaining traction now?

“There is a pending perfect storm of market conditions poised to tip the scales.”

There is a pending perfect storm of market conditions poised to tip the scales. More and more traditional processes are shifting to vacuum for its long list of advantages, including tighter process control, flexibility, safety, insurance liability, and improved working environment, just to name a few. This push to convert more processes is driving a need to optimize efficiency and improve cost. The existing approach has known intrinsic inefficiencies and a limited growth path for improvement.

As more heat treaters either experience or compete with the benefits of multi-chamber isolated heat equipment, adoption will continue to accelerate.

Challenges and Considerations

While isolated heat furnaces offer numerous advantages, they are not without challenges. These systems are more complex, require a detailed specification process, and may not be suitable for very large components, intermittent operations, or applications requiring a high degree of flexibility. Many of the advantages of multi-chamber equipment show up in operating and maintenance costs. These benefits can be missed if these costs are not properly accounted for in the ROI analysis phase. Overemphasizing upfront costs can mean missing out on a much better return on investment for equipment with installation life in the range of 20–30 years.

Applications and Future Prospects

Isolated heat vacuum furnaces are not industry specific; rather, they offer advantages across a wide range of applications. Processes characterized by short cycle times benefit because a greater percentage of the floor-to-floor time is dead time and can be recovered, improving equipment utilization. Processes characterized by long cycle times benefit because they can be segmented and indexed at much faster rates, increasing throughput. Surface treatments can benefit from the process uniformity of smaller load sizes without sacrificing throughput. High-volume production environments, in particular, stand to gain the most. Whenever there is a need for more than one batch furnace or where there are numerous small parts in a large work zone, the efficiency and cost savings of continuous isolated heat furnaces truly stand out.

Conclusion

The industry’s focus on efficiency, reduced emissions, and lower operating costs makes isolated heat vacuum furnaces a promising direction for the future. While single-chamber furnaces will still have their place, isolated heat furnaces are becoming more prevalent for many heat treatment processes. Offering superior energy efficiency, better process control, and a more sustainable approach to thermal processing, these furnaces will enable manufacturers to provide high quality, cost-effective solutions that meet today’s market demands and future challenges.

About the Author:

Bryan Stern
Product Development Manager
Gasbarre Thermal Processing Systems

Bryan Stern has been involved in the development of vacuum furnace systems for the past eight years and is passionate about technical education and bringing value to the end-user. Currently product development manager at Gasbarre Thermal Processing Systems, Bryan holds a B.S. in Mechanical Engineering from Georgia Institute of Technology and a B.A. in Natural Science from Covenant College. In addition to being a member of ASM, ASME, and a former committee member for NFPA, Bryan is a graduate of the MTI YES program and recognized in Heat Treat Today’s 40 Under 40 Class of 2020.

For more information: Contact Bryan at bstern@gasbarre.com.

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Voices in Heat Treat: Vacuum Brazing Revisited

October 29, 2024 / BRAZING TECHNICAL CONTENT, MANUFACTURING HEAT TREAT TECH, TITANIUM PROCESSING TECHNICAL CONTENT, VACUUM FURNACES TECHNICAL CONTENT

The heat treat industry is rich with knowledgeable leaders, resourceful problem solvers, and innovative teams. One of our favorite things to do here at Heat Treat Today is to draw attention to the wealth of expertise in the field, so we are pleased to launch the Voices in Heat Treat series, pointing readers to a treasure house of recorded interviews and discussions diving into the fundamentals of thermal processing.

In this and coming articles drawn from the audio library at Solar Atmospheres, we will summarize topics on everything from basic heat treating how-tos, preventative maintenance, and troubleshooting to the history of hot zone designs, temperature uniformity surveys, and the distinctions to take into consideration when processing different kinds of metals and alloys. In today’s installment, our industry experts focus on vacuum brazing and the uniqueness of heat treating titanium.

In the premiere article of this series, Bill Jones, founder and CEO of Solar Atmospheres and Solar Manufacturing, interviews industry leaders about the advantages of vacuum furnace brazing. Read the highlights of their discussion about the process, in particular when used with stainless steel and titanium. The summary of a fourth episode recorded earlier has been added, expanding on the topic of the advantages of processing titanium in a vacuum furnace. The experts are Calvin Amenheuser, vice president of the Hatfield plant, and Mike Paponetti, sales manager of the southeast. Jim Nagy, senior vice president of Solar Manufacturing, hosts the episodes. A summary of each conversation is below, followed by links that will take you directly to that podcast episode.

Bill Jones and the Team Speak on Vacuum Brazing, a 3-Part Series

“Advantages of Vacuum Furnace Brazing”

December 2015

Brazing to form strong metallurgical bond where the brazed joint becomes a sandwich of different layers, each linked at the grain level

This episode is the first in a series on vacuum furnace brazing, with an overview of different types of brazing processes and why vacuum furnace brazing is superior to other joining methods, particularly torch brazing and welding.

The conversation explores various reasons why a vacuum furnace is well-suited to perform brazing because it provides:

a controlled, consistent atmosphere cycle after cycle
uniform heating throughout the hot zone
a controlled rate of heating
the elimination of air to prevent the formation of oxidation of the metal

Vacuum Furnace Brazing vs. Alternative Methods

Both Cal Amenheuser and Mike Paponetti speak about vacuum brazing being a superior process to alternative methods. Mike noted that torch brazing is effective for low volume loads, but the process risks flux entrapment and could produce messy, overheated and possibly carburized parts. In contrast, vacuum furnace brazing allows for higher volume loads, providing a repeatable process, precise temperature measurements, and versatility.

Brazing applications from parts to rockets

Calvin added that while welding melts the materials and produces a strong joint, the surrounding material is weaker. With vacuum furnace brazing, the brazed joint is just as strong or stronger afterward as before.

Finally, the panelists compared how batch vacuum furnace brazing eliminates distortion that is typical with torch brazing and welding because of hot zone uniformity. A batch furnace operator can modify the process to meet the demand of the load, and furnace charts provide proof of reveal what exactly happened during the run so that successful recipes can be repeated.

Click here to listen to this episode.

“Vacuum Brazing of Stainless Steel”

February 2016

In this episode, second in the series on the vacuum furnace brazing, the Solar team reconvened to discuss advantages of and concerns with nickel-based and copper-based brazing alloys.

All agree that nickel-based alloy offers a cleaner braze but emphasize precautions must be put in place to avoid metal erosion and cracking. While readily available and a good match for low carbon steel, copper flashes during the braze. Inert gas is recommended to decrease evaporation of the copper-based alloy.

Click here to listen to this episode.

“Processing Titanium in Vacuum Furnaces: Active Brazing of Titanium in a Vacuum Furnace”

April 2016

In this third and final episode on the topic of vacuum furnace brazing, Bill Jones, Calvin Amenheuser, and Mike Paponetti consider significant challenges to brazing titanium, which is the need to reduce surface oxide to allow the process to take place and why active brazing is suggested as a means to meet that challenge. What follows is an informative discussion on composites that allow producing companies add to the material, like hydrated titanium, zirconium, and indium, to help overcome oxides, which are effective at wedding to the surface.

Click here to listen to this episode.

Additional Notes on Titanium

“Processing Titanium in Vacuum Furnaces: Advantages”

February 2013

175,000 pounds of 6Al-4V titanium in Solar’s 48-foot-long vacuum furnace

Although recorded earlier than and thus separately from the series on vacuum furnace brazing, this summary of an episode is included in this article to provide context about the advantages of processing titanium in a vacuum furnace. This is a solo Bill Jones episode.

Bill Jones highlights how vacuum furnaces provide a pure atmosphere for processing titanium compared to an argon atmosphere, saving machining costs and time. Additionally, vacuum processing uses forced inert gas quenching to cool titanium as opposed to water quenching which results in a more uniform result and eliminates part distortion. Finally, fixturing parts properly in a vacuum furnace with graphite allows heat treaters to preserve the part shape and avoid movement.

Click here to listen to this episode.

We share these resources from the audio library at Solar Atmospheres.

Bill Jones
Founder & CEO
Solar Atmospheres, Solar Manufacturing
Source: Solar Atmospheres

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Consulta a The Heat Treat Doctor®:¿Cómo determinar cuál medio detemple utilizar?

October 8, 2024 / HARDENING TECHNICAL CONTENT, MANUFACTURING HEAT TREAT TECH, QUENCHING TECHNICAL CONTENT

The Heat Treat Doctor® ha vuelto para ofrecer sabios consejos a los lectores de Heat Treat Today y para responder a suspreguntas sobre el tratamiento térmico, brazing, sinterizado y otros tipos de procesamiento térmico, así como preguntassobre metalurgia, equipos y problemas relacionados con los procesos.

This article was originally published in Heat Treat Today‘s September 2024 People of Heat Treat print edition.

To read the article in English, click here.

El temple es un paso fundamental en el proceso de tratamiento térmico. Y si bien el especialista en tratamiento térmico suele tener varias opciones disponibles, existe un delicado equilibrio entre lo que está disponible para nosotros y cómo podemos optimizar sus características de rendimiento para cumplir con los requisitos/especificaciones de nuestros clientes. Se deben tener en cuenta cuidadosamente el material, el diseño de la pieza (geometría), los requisitos previos y posteriores de manufactura, la carga, el cambio dimensional permitido (es decir, la distorsión) y el proceso como tal. Conozcamos más.

Medios de temple: una breve Descripción

Los medios de temple actuales ofrecen una amplia gama de capacidades que, en algunos casos, se traslapan. Sin embargo, en un nivel fundamental, la función de un medio de temple es extraer calor de la superficie de la pieza para cumplir con una velocidad crítica de enfriamiento especificada y con ello lograr la microestructura necesaria para lograr las propiedades mecánicas y físicas requeridas. En el temple de aceros, por ejemplo, se debe evitar pasar por la “nariz” de la curva de transformación-tiempo-temperatura (TTT) si el resultado final deseado es una microestructura martensítica (o bainítica). Por el contrario, la velocidad de enfriamiento para un proceso de normalización requiere enfriamiento “al aire”, un término que a menudo se malinterpreta y que abordaremos en una discusión futura.

Figura 1. Medios de Temple comunes y su efecto en la distorsión (1)

Sin embargo, un medio de temple (Figura 1) es más que solo su velocidad de enfriamiento. Los medios de temple deben ser estables durante su vida útil, especialmente con respecto a la degradación (por ejemplo, oxidación), ser seguros, ser fáciles de arreglar y mantener, tener un alto punto de vaporización, idealmente no interactuar con la superficie de la pieza, usarse dentro de su rango de rendimiento óptimo, tener una larga vida útil, eliminarse fácilmente mediante limpieza después del temple y ser rentables.

A manera de una caracterización muy amplia, los medios de temple se pueden dividir en las siguientes categorías generales:

Medios de temple líquidos (p. ej., a base de agua, aceites, polímeros, sales fundidas y metales fundidos)
Medios de temple gaseosos (p. ej., aire, nitrógeno, argón, hidrógeno, vapor, dióxido de carbono, dióxido de azufre, gases reductores, atmósferas protectoras sintéticas o generadas, gases a alta presión)
Medios de temple sólidos (p. ej., dados de prensa enfriados, placas y polvos)
Medios de medios mixtos (p. ej., temple por aspersión, lechos fluidizados)

Figura 2. Diagrama de Ishikawa (también conocido como de pescado) de las variables de temples (1)

Selección del medio de temple óptimo

Se deben tener en cuenta varios factores al seleccionar el mejor medio de temple. A continuación, se enumeran algunos de los aspectos importantes a tener en cuenta al seleccionar el medio adecuado (Figura 2):

Material: composición química, templabilidad, forma (p. ej., barra, placa, forja, fundición), tipo (p. ej., forjado, sinterizado) y limpieza, por nombrar algunos
Geometría/diseño de la pieza: forma, tamaño, peso, complejidad
Estado de laminación o tratamiento térmico previo: recocido, normalizado, preendurecido, relevado de esfuerzos
Estado de tensión: el efecto acumulativo de las operaciones de laminación y las operaciones de fabricación del cliente antes del tratamiento térmico
Carga: canastillas (aleación, compuesto C/C, placas de grafito, etc.)
Parámetros del proceso: temperatura, tiempo, precalentamiento
Selección del equipo: ¿es óptimo o simplemente adecuado para el trabajo?
Medio(s) de temple disponibles: sus limitaciones y ventajas

Es importante hablar brevemente aquí sobre dos aspectos del proceso de selección del medio de temple. Primero, observar la diferencia entre dureza y templabilidad (que analizaremos con más detalle en el futuro). Los tratadores térmicos tienden a centrarse en la dureza (ya que podemos medirla fácilmente en nuestro taller), pero la templabilidad es una consideración crítica en la selección del medio de temple. La templabilidad es una propiedad del material independiente de la velocidad de enfriamiento y dependiente de la composición química y el tamaño del grano. Cuando se evalúa mediante pruebas de dureza, la templabilidad se define como la capacidad del material bajo un conjunto dado de condiciones de tratamiento térmico para endurecerse “en profundidad”. En otras palabras, la templabilidad se relaciona con la “profundidad de endurecimiento”, o el perfil de dureza obtenido, no con la capacidad de alcanzar un valor de dureza particular. Cuando se evalúa mediante técnicas microestructurales, la templabilidad se define (para aceros) como la capacidad del acero para transformarse parcial o completamente de austenita a un porcentaje definido de martensita.

Tabla 1. Valores medios e instantáneos del coeficiente de transferencia de calor (3)

En segundo lugar, se debe tener en cuenta tanto el valor medio como el instantáneo del coeficiente de transferencia de calor alfa (α) del medio de temple. Aunque la “potencia” máxima de temple se puede describir mediante el coeficiente de transferencia de calor instantáneo, el coeficiente de transferencia de calor promedio (Tabla 1) proporciona una mejor comparación relativa de los diversos medios de temple, ya que representa el valor del coeficiente de transferencia de calor en todo el rango de enfriamiento (desde el inicio hasta el final del temple). Es importante recordar que la capacidad de gestionar (no controlar) la distorsión es un delicado acto de equilibrio entre la extracción uniforme del calor y la transformación adecuada.

Tabla 2. Clasificación de los aceites de temple (1)

Un ejemplo común: selección de aceite de temple

Los factores importantes a tener en cuenta al seleccionar un aceite de temple, que son válidos en una forma ligeramente modificada para la mayoría de los medios líquidos, son: el tipo de medio (es decir, características del temple, datos de la curva de enfriamiento, nuevo y a lo largo del tiempo); velocidad de temple (consulte a Tabla 2); temperatura de uso; volumen efectivo del tanque de enfriamiento [es decir, la regla de un galón por libra de acero (8,4 L/kg)]; y los requisitos del cliente.

Los factores de diseño del tanque de temple también juegan un papel importante e involucran lo siguiente:

Volumen de aceite en el tanque de temple
Número de recirculadores o bombas
Ubicación de los recirculadores
Tipo de recirculadores (velocidad fija ovariable)
Disposición de los deflectores internos del tanque (tubos de aspiración, álabes de flujo direccional, etc.)
Diseño del elevador de temple (es decir, restricciones de flujo)
Dirección del flujo del temple (hacia arriba o hacia abajo a través de la carga)
Tamaño de la propela (diámetro, espacio libre en el tubo de aspiración)
Máximo incremento dela temperatura (diseño) delaceite después del temple
Altura del aceite sobre la carga
Intercambiador de calor: tipo, tamaño, tasa de extracción de calor (BTU instantáneos/minuto)
Tiempo de recuperación del aceite hasta el set point

Por último, se deben tener en cuenta factores como: la masa de la pieza; la geometría de la pieza (por ejemplo, secciones delgadas y gruesas, esquinas y barrenos afilados, perfil de los dientes del engrane, perfil de la rosca, etc.); espaciamiento de la pieza en la carga; velocidad de flujo efectiva a través del área de temple (vacía y con carga); estado de tensión de operaciones anteriores (de manufactura); operaciones de tratamiento térmico posteriores a realizar (si las hay); carga, incluidas las charolas, las canastillas y el herramental (material y diseño); y el material (composición química y templabilidad).

Reflexiones finales

El temple, considerado por muchos como un tema complejo y multifacético, es un asunto que los especialistas en tratamiento térmico deben supervisar y controlar constantemente. En futuras entregas, analizaremos muchos de los aspectos individuales del temple. Lo importante aquí es reconocer que, si se realiza correctamente, el temple (en cualquier forma) optimizará un tratamiento térmico determinado y ayudará a producir las piezas de la más alta calidad que exigen las industrias a las que prestamos nuestros servicios.

Referencias

Daniel Herring, Atmosphere Heat Treatment, Volume II: Atmospheres | Quenching | Testing (BNP Media Group, 2015).

Bozidar Liscic et al., Quenching Theory and Technology, Second Edition (CRC Press, Taylor Francis Group, 2010).

Daniel Herring, “A Review of Gas Quenching from the Perspective of the Heat Transfer Coefficient,” Industrial Heating, February 2006.

Sobre el autor

Dan Herring ha trabajado en la industria durante más de 50 años y ha adquirido una vasta experiencia en campos que incluyen ciencia de materiales, ingeniería, metalurgia, investigación de nuevos productos y muchas otras áreas. Dan es
autor de seis libros y más de 700 artículos técnicos.

Para más información: Comuníquese con Dan en dherring@heat-treat-doctor.com.

For more information about Dan’s books: see his page at the Heat Treat Store.

Find Heat Treating Products And Services When You Search On Heat Treat Buyers Guide.Com

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