A major automotive parts supplier has awarded a contract for the complete overhaul and refurbishment of a cast link belt normalizing furnace to Can-Eng Furnaces International Ltd. Designed and manufactured by Can-Eng in 1996, the equipment was originally rated at 27,000 lbs./h of hot charged closed die forgings and was known to be one of the largest cast link belt furnaces in the world at the time.
Normalizing Furnace (source: heatprocessing.com)
The refurbishment will take place in the Can-Eng Niagara Falls shops and will consist of a complete refractory reline, new combustion, new control panel, and Level II automation system, plus an added external cooling conveyor. The furnace shell, hearth, and return rolls, as well as the ACI HT cast link belt itself, will be refurbished to near new condition.
The system will employ a furnace charging robot. The entire operation will be completely automated from the furnace charging robot pick position through the heat treatment process.
The furnace line will go back into operation in Q1 of 2021 in the United States for normalizing of alloyed automotive forgings.
Ernesto Perez, Director of Engineering, Nutec Bickley
In today’s Heat Treat TodayTechnical Tuesday feature, Ernesto Pérez, Director of Engineering, at Nutec Bickley, introduces readers to different options when it comes to furnace temperature control.
The main aim of the temperature control function is to keep a furnace operating within certain predefined values and it is composed of two main parts:
Electronic control element, usually a PID (proportional–integral–derivative) controller
Mechanical components
In this article we will look at the various control modes used in industrial furnaces, and their applications for various heat treatment processes.
Back to the Beginning: “Zero Control” Mode
Figure 1
Before considering the modes currently used, we should briefly mention the “zero control” mode found in earlier furnace models, employed some time back, also known as “atmospheric mode.”
This mode operates by taking air from the environment by means of the venturi effect to perform combustion without controlling the air flow, resulting in an inefficient use of energy. (Figure 1)
Fuel-Only Control System
Figure 2
This operates in a similar way to zero mode, where only the gas is controlled. However, instead of the air being introduced by the venturi effect, there is a turbo fan that provides a constant flow to the process, while the gas is regulated during the different stages of combustion. (Figure 2)
Economic system having a single line of control.
It provides good temperature uniformity in applications where all items being fired in the furnace need to be at the same temperature.
Ideal for low temperature furnaces, kilns for ceramics and applications that require high-level heating homogeneity.
Possible Disadvantages This technique leads to high gas consumption due to the heating of all the air present, irrespective of the size of the load in the furnace.
Proportional Control System
Figure 3
With this control mode, the air and the gas are controlled proportionally. (Figure 3)
The operation starts with a small flame, and as the temperature rises, it grows as the air and gas levels increase.
This system allows you to adjust the amount of gas based on the air present in order to achieve perfect combustion and optimal fuel consumption.
Ideal for any type of furnace, for example for heat treatments such as aging, tempering, forging and normalizing.
Possible Disadvantages At the beginning of the heating process, it can be the case that temperature uniformity across the entire furnace is not so good due to the small flame, so it is not a system recommended for the treatment of very fragile pieces that can break.
Mass Flow Control System
Figure 4
This system controls air/gas in the same as the previously described method, but it also gives allowance to vary the air/gas ratio during combustion process in order to optimize the fuel. (Figure 4)
It enables for the achievement of optimal combustion conditions with less energy input.
If more air is needed in a particular heat treatment stage (usually at the beginning), it can be temporarily increased.
Ideal for any type of furnace, like heat treatments such as aging, tempering, forging, normalizing and applications involving fragile products.
Possible Disadvantages Because of the technology behind the system, it is more expensive.
Pulse Control System
Figure 5
This is one of the most recently introduced methods that provides a fixed air/gas ratio, but unlike the previous mentioned systems, flame velocity for product heating is always high, which generates ideal temperature uniformity right from the beginning of the cycle. (Figure 5)
The burners pulse from high-fire to low-fire, repeating this cycle every 15 to 60 seconds.
It is cheaper to operate than the mass flow system, allowing users to handle the entire range of products with a smaller investment.
It provides greater fuel efficiency by heating the product evenly from the beginning.
Ideal for any furnace, for example for heat treatments such as aging, tempering, forging, normalizing and applications involving fragile ceramic products.
Possible Disadvantages The radiation of the flame can affect certain products; however, by installing an additional instrument it is possible to control this effect and to reduce flame radiation.
Experts in Temperature Control
Nutec Bickley can offer all current systems, advise on the most appropriate choice with the best cost benefits, update old systems with current technology, and provide repair and spare parts services for existing temperature control systems.
About the author: Ernesto has been sharing his expertise at Nutec for 18 years. As an electronic system engineer with a master’s degree in artificial intelligence, the 25-year industry veteran has been focused on the control aspect of software and hardware.
A research organization recently awarded a contract to a North American furnace manufacturer for the supply of a rapid-heating furnace to be used for product development of lightweight hot-stamped and formed aluminum automotive components. This organization will integrate the aluminum-sheet heating furnace with existing equipment to support both automotive manufacturers and Tier 1 suppliers throughout North America.
(source: Can-Eng)
Can-Eng Furnaces International Ltd., of Niagara Falls, Ontario, was chosen for this project because it has significant experience in the development of lightweight, thin-walled automotive structural components. Can-Eng provided the customer with a unique rapid-heating furnace system that offers significant reduction in floor space requirements, flexibility for processing a wide range of product sizes, and the flexible operating temperatures required for various stamped and formed products. The system will be fully integrated with flexible robotic handling and material handling automation.
When it comes to hardness testing nowadays, the process does not have to be done manually; automation has taken much of the burden away from operators. But which way produces the better result?
In this Heat Treat Today Original Content feature, Buehler recently published the results of a time study that compared case hardness testing of automotive crank pins and journals using both automation and manual testing. Find out which method showed a definite edge over the other in terms of time saved, less part manipulation, fewer errors in data transcription, and lower variability between performing tests.
EXECUTIVE SUMMARY
A study shows an operator time savings of 86% for making and measuring indents in three locations of crank pins and journals when using automation compared to manual testing. There was less part manipulation, fewer errors in data transcription and lower variability between operators performing tests.
INTRODUCTION
A large automotive manufacturer wanted to investigate the potential time savings of using automation for hardness testing crank pins and journals. Their existing process required two skilled operators per shift, two shifts per day, seven days per week. Tests were performed in three specified locations, two at forty-five degrees off axis and one perpendicular to the axis. Specified locations are critical, as missed locations could lead to manufactured parts being held in quarantine until further confirmation can be performed. Also of concern are failed parts that were inadvertently passed being installed and ultimately being prone to catastrophic failures. Data transcribing error was also a concern; if part information was entered incorrectly in a separate database it would cause mismatched data to lot number. When this occurs, it causes parts to become quarantined until the part information can be verified. With the total scrap cost being a considerable factor, skilled trained operators are needed for testing. Round robin testing is also used to determine the variability between operators. Qualifying new lines put into production increased testing by a factor of three to five times the normal operation analysis rate.
OBSERVATION
Current Process Observation
An evaluation of time to make and measure Vickers indentations on automotive crank pins and journals was established to determine a baseline of time for the existing process. Testing was done on a standalone manual system and required operator time for alignment, making and measuring of indents. The operators would fixture parts in similar orientation to ensure that measurements of the forty-five degree axis were in close proximity to expedite testing and reduce errors in testing. A high degree of manipulation for part alignment is necessary prior to physical testing to ensure accuracy.
It was observed that the operators’ set up time for location took the largest amount of testing time at 60%, measuring indents taking the second largest amount of time at 30% and making indents the third largest amount at 10%. The total amount of indents per pin and journal varied but averaged eighteen indents per section; six in each location. Total amount of indents for a crankshaft, pins being measured top dead center and bottom dead center and journals being measured along split, was 216 indents on average. The total analysis time for making and measuring indents at the specified locations on a crank was nine hours with 8 hours of operator interaction.
Implemented Process
For the implemented process a Wilson VH3100 series Vickers Microhardness Tester with DiaMet software was used. Parts were clamped in a machinist vice and placed on the stage without manipulation of orientation.
Figure 1.1 – Crank pin held in machinist vice (source: Buehler)
Trace function was used with the overview camera to create a template of the part to be tested; minimizing the set up time for the indent locations. The use of the template reduced the location set up time to 45 seconds in the three areas; two at forty-five degrees and one perpendicular to case.
Figure 1.2 – Trace function template for ease of indent locations (source: Buehler)
The DiaMet software snapped the template to the part at the specified location and the operators confirmed location. Observation of the set up time, making and measuring indents was 10, 50 and 40 percent respectively. Total amount of indents for a crankshaft was 216 indents on average with of time 1.25 hours with 15 minutes of operator interaction.
Figure 1.3 – Indent make and measure being performed automatically (source: Buehler)
Visual high and low threshold warnings were added to each program giving the operator the ability for quick assessment of parts versus the confirmation after all crank pins and journals were analyzed as it was in previous methodology.
Figure 1.4 – Visual high low threshold warnings to alert operators of hardness thresholds (source: Buehler)
For reporting, metadata was set up to prevent operator errors in transcribing data.
The time study evaluation shows automation saves a significant amount of time with setup as well as the time required to make and measure the Vickers indents. The total amount of time that the operators spend setting the indent profile, measuring and compiling data is reduced by 86% as well as avoiding any errors in transcribing data. Repeatability of testing is increased operator to operator, as variability between operator judgement is eliminated. The combination of using trace function and templates eliminated the need for operators to spend time aligning parts on the stage as well as mitigated the risk of a misplaced indent profile. The increase of visibility of part failure is evident at time of measurement and gives the operator the ability to recheck either an area or total part without the need for extended quarantine of parts for re-examination. Using metadata fields within the Vickers testing program removed transcribing issues which would hold up batches of cranks until records could be reviewed.
Three batch steam treaters were recently shipped to the medical and automotive industries. Gasbarre Thermal Processing Systems recently received three separate orders for batch steam treating equipment. The batch steam treaters produce an oxide layer that promotes corrosion and wear resistance properties and provides an attractive surface finish. The three unique orders range in size from 18” to 30” in diameter and 12” to 48” deep. The gross load weight capacity ranges from 300lbs to 1800lbs with Gasbarre supplying the production tooling. The equipment is electrically heated and has a maximum operating temperature rating of 1400℉.
Steam treating processes are used in many different industries. As such, these orders will be shipped to companies that provide products to the medical, additive manufacturing, automotive and consumer products industries.
Stryker Hero JR Hip Replacement Source: Stryker.com
This week’s Technical Tuesday installment is a Heat Treat Today original that was first published in the Heat Treat Today Automotive magazine in June 2019.
This industry is richly endowed with a heritage of experienced metallurgists and skilled professionals. This era is one of innovation and trends – especially in automotive manufacturing. How does the heritage of the industry and the vision of the future come together? We’ve compiled input from a selection of Heat Treat Today’sown industry experts on a question about new stuff going on in both the labs and the shops. (To see what other fields and specialties our Heat Treat Consultants work in, go to: www.heattreattoday.com/consultants)
Question: “Thinking about the automotive heat treating industry, what is one of the more interesting, innovative or helpful technologies, processes, materials, or products that you’ve seen recently?”
The Heat TreatBrain Trust Responds:
Sandra Midea
Sandra Midea is a consulting metallurgist and founder of Midea Group Inc.
I’ve had the opportunity to work first hand with an induction company in North Royalton, Ohio, (Induction Tooling Inc.) to create an in-house facility that develops and validates induction heat treating processes. The objective was to create a space with the right equipment and personnel where induction processes and tooling could be tested—to innovate, to provide proof of concept, to troubleshoot, and/or to validate processing parameters, in the most streamlined process available. For the automotive industry,
the lab has been used to reduce the time required to get products/processes ready for the PPAP. Bill Stuehr, the company’s president and CEO, had the vision that induction process development could occur rapidly by condensing the design, manufacturing, development, testing, and characterization and metallurgical validation processes all into one facility. With seven power supplies from different manufacturers and three material handling systems available for induction process development, an automotive supplier’s production induction heat treating department can be mimicked for power, frequency, quench & quench method, and material handling methodology. This allows incremental process and tooling development to occur in a laboratory environment without the cost of breaking into production.
This development facility is backed up with an ISO 17025 commercial metallurgical testing laboratory. Sample parts are checked for appropriate microstructure, grain size and hardness requirements and reported to the customers. Initial lots of evaluation parts can also be produced. This allows the inductor and process to be developed and validated before the tooling ships to the heat treating customer. While some process tweaks may need to occur at the final facility, the time required for a company to be ready to begin the PPAP process can be significantly reduced.
Max Hoetzl
Max Hoetzl previously served as president of IHEA and vice president of technology with Surface Combustion, Inc.
One of the most interesting things I’ve seen in the automotive heat treat industry is the use of robots to load and unload furnaces. The use of robots has significantly improved the operation in many ways.
Following are some of the examples:
Remove humans from hazardous environment,
Increase throughput,
Provide part loading for uniform thermal treatment.
Joe Benedyk
Joseph Benedyk is a research professor at Illinois Institute of Technology and a mining & metals consultant. (Image source: Light Metal Age)
Reducing Heat Treatment Time in the Precipitation Hardening of Aluminum Alloys
Strengthening aluminum alloys through the precipitation hardening process by solution heat treatment and aging is considered a fundamental step in the manufacturing of high strength-to-weight products that meet performance requirements in both the aerospace and automotive industries. The automotive industry is focusing on 7xxx alloys because of their high strength. Among the high strength 7xxx (Al-Mg-Zn) alloys is the mainstay alloy 7075, which can achieve a tensile strength of as high as 80 ksi when age hardened to a -T6 temper. However, to achieve these high strength levels in 7075 alloy at conventional aging temperatures requires aging for 24-48 hours, a stumbling block to its application in automotive products.
Figure 1. Comparison of age hardening curves for 7075 alloy solutionized at 914°F (490°C) and water quenched: A1 and A2 aged in a single step
Research at the Illinois Institute of Technology Thermal Processing Technology Center has shown that by selectively double aging 7075 alloy, the aging time to achieve maximum hardness and strength can be reduced to as low as two hours under laboratory conditions (see Figure 1) or demonstrably much shorter aging times in an extrusion plant trial. The obvious advantages of significantly shorter aging time for 7075 and other heat treatable aluminum alloys are not only energy savings but also increased plant productivity through much reduced processing time. The begged question of applying the double aging process to other heat treatable wrought aluminum alloy systems is under review.
Jim Senne
Jim Senne is the owner and president of MetalPro Resources, LLC.
PSA generated nitrogen has become increasingly popular for use in heat treating applications, and at a fraction of the cost, due to advances in PSA technology. Typical cost per standard unit volume are 15% to 25% of the cost of bulk liquid nitrogen. Purity can range from 95% to 99.999%, however many processes demand less than full purity. PSA technology can dial into the specific requirement, making it even more economical. The equipment has excellent reliability and requires only general maintenance on the associated air compressor and periodic filter changes. As well, the CMS (Carbon Molecular Sieve) material can last 20+ years. Processes that require a nitrogen cover gas are particularly well suited, such as induction hardening, tempering, and stress relieving. Other suitable applications include nitrogen/methanol atmosphere, FNC, N2+scavenger gas mixes, and purging.
Matt Orfe
Matt Orfe, an expert in lean manufacturing, is the head of sales and VAB product management for AeroSPC, Inc.
One of the most impressive pieces of equipment that I’ve seen in use in VAB (vacuum aluminum braze) furnaces in the automotive industry would be the in-furnace data loggers for monitoring the temperature of the parts being brazed. The instrument is loaded into the VAB furnace with the parts to be brazed and wirelessly transmits the temperature data through the furnace chamber wall to the receiver/monitor.
This eliminates the need to plug in thermocouples with the furnace door opened, as the load sensors can be attached to the unit prior to insertion into the chamber.
Multiple thermocouples can be used with the system and multiple data logger units can be used for high volume applications. Very accurate, very easy-to-use, and very impressive!
Debbie Aliya
Debbie Aliya is founder and president of Aliya Analytical, Inc.
My instant response is always that the most innovative, interesting, and helpful technologies are educational in nature— the knowledge that allows people to make the best use of the common materials that still form the foundation of our industry. How many products would be more reliable if people properly selected, specified, and inspected the heat-treated materials that they use? How many products would be more reliable if the purchasing and specifying functions had a realistic idea of how much variation they should expect in a given part, lot, from lot to lot, and over an extended period of time? For example, how many people in engineering and purchasing know what a furnace uniformity survey is?
Purchasing often does not want to use an alloy steel, but if they need uniformity of strength, and there are different section thicknesses, they may save money and headaches if they pay the extra up-front to get the hardenability into a range that will provide consistency.
How many companies have minimum hardness or case depth specifications, without an upper limit? If the parts are to be electroplated, they increase the risk of hydrogen embrittlement, an issue that seems to come around in the industry every 10 years or so.
It wasn’t an automotive company, but I have had at least one client specify a quench and temper heat treatment for an HSLA (high strength low alloy) steel, which completely defeats the purpose of the HSLA grade system.
There are still a lot of people doing design work who think that calling out a composition requirement gives a certain strength level. For many of the European and Asian steel specifications, this is true, but the American specifications are often for composition only.
How many companies still do not require lot traceability? In the automotive world, if it’s a critical part, traceability is generally required, but there are still a lot of parts that fall through the cracks.
Doug Shuler
Doug Shuler is the owner of Pyro Consulting LLC.
The most interesting thing I have seen in the automotive heat treating industry is a new pyrometry technology software system known as C3 Data.
This solution enables those in the heat treatment industry to comply with specific industry quality requirements of pyrometry, saving enormous amounts of time in the process.
While C3 Data is currently better known in the Nadcap world for their solution for AMS2750, their new CQI-9 version should be something that heat treaters in the automotive world consider.
This fits with my motto of working smarter—not harder!
Irwin Brown
Irwin Brown is Managing Principal & Co-founder of Cosmos Consulting Group.
Nowadays, the heat treating industry, especially automotive, enjoys an abundance of riches. We are witnessing increased business volume coupled at the same time with efficient new equipment and technologies, such as additive manufacturing, AI, supply chain improvements, and amazing software. So, why are so many thermal processors unable to raise EBITDA? We are also witnessing critical worker shortages as well as many current employees voluntarily resigning in record numbers. What is the secret to improved quality and increased profits? In our work with industry clients, we found a way to lead employees to better serve customers, thus unlocking vast potential. This strategy, based upon a little deployed thirty-year old method, provides a rapid turnaround that makes productivity soar.
This “secret sauce” is Servant Leadership, which remains the best and most useful technique for transforming difficult relationships among modern multi-cultural employees. Old style command-and-control employers hesitate to recognize and acknowledge how decades-old management behavior is unsustainable with today’s workforce. More enlightened owners, in their own self-interest, value a more dedicated workforce. Employees do not leave companies; employees leave their managers.
Servant Leadership permits owners to run their business rather than having the business run them. Building strong, working relationships creates positive results and is not soft leadership. As Ken Blanchard likes to say, “the power of love beats the hell out of the love of power.” Servant Leadership costs nothing and has proven it can spearhead a rapid turnaround.
Dan Herring
Dan Herring is The Heat Treat Doctor® at The HERRING GROUP, Inc.
Intriguing question. In my mind, it is the emergence of the electric car and the innovations it will spawn. The motivation is there: a new generation that demands to be green, countries such as China passing laws on vehicle energy reduction (a so-called energy vehicle score), and technological improvements. Battery performance is rising (distance per charge), battery costs are falling (potentially lowering vehicle cost), battery life is up, and weight reduction is a reality. Another reason is the simplicity it brings to the vehicle (the absence of a multi-speed transmission, for example) and a reportedly lower cost for common repairs (this might be a bit misleading as one has only internal combustion engine vehicles to compare with).
While the transition has begun, I feel there are two major hurdles to overcome. First is infrastructure. A massive investment is required to make recharging as available to the public as stopping now to get gas. Every gas station in any country in the world must be mandated to have multiple charging stations. The hidden issue here, both domestically and around the world, is that it will require changes in the law – and the fossil fuel lobbyists are powerful, well established, and entrenched in the government sector. Also, the cost of electricity (in some regions of the world) is not price competitive. Second is public perception. Yes, everyone wants one, but who wants to be first? The phrase I like to use is that John Q. Public doesn’t mind being on the cutting edge, he just doesn’t want to be on the bleeding edge.
Sometimes our editors find items that are not exactly “heat treat” but do deal with interesting developments in one of our four key markets: aerospace, automotive, medical, or energy. As we approach the weekend, today’s Heat Treat Fringe Friday, Best of the Web post focuses on an interesting development in the automotive industry.
Raphael Koch, research engineer, Advanced Materials and Processes, Ford of Europe (source: LinkedIn.com)
It’s one of the worst experiences a proud car owner can experience–walking out to their beloved vehicle to discover all four wheels are gone. As alloy wheels and vehicle customization have grown in popularity, component theft has unfortunately become a lucrative side business. “Some alloy wheels can cost thousands to replace, but these unique rim nuts will stop thieves in their tracks. Making wheels more secure and offering more product personalization are further proof that 3D printing is a game-changer for car production,” says Raphael Koch, research engineer, Advanced Materials and Processes, Ford of Europe.
Michael Jan Galba, Head of Global Consulting & Manufacturing Engineering at EOS (source: LinkedIn.com)
Ford engineers wanted to help customers find a solution, hence the advent of a theft resistant lug nut. The project was the result of a brainstorming session focused on finding applications for additive manufacturing within the company. In collaboration with additive manufacturing solutions provider EOS and software developer Trinckle, engineers at Ford have now developed unique locking wheel nuts using 3D printing technology. “We thought about using fingerprinting, or an iris scan or something that could actually modify the groove or curve of the lug nut,” says Michael Jan Galba, Head of Global Consulting & Manufacturing Engineering at EOS. “Trinckle proposed adapting an application they used in a completely different industry that utilized a voice wave curve.”
A North American steel supplier announced today that it has begun operating its continuous galvanizing line, which will produce hot-dip galvanized sheet steel for the automotive market. Nucor-JFE Steel Mexico, located in Silao, Guanajuato in central Mexico, has begun trial production and will move towards full-scale sales and production once customer approvals have been obtained.
Leon J. Topalian, president and CEO, Nucor Corporation
“We are excited to expand our presence in Mexico and to use our local sales network to increase our sales into this important automotive market,” said Leon Topalian, President and CEO of Nucor. “We are proud to partner with JFE Steel Corporation of Japan and to benefit from their experience as a premier supplier of high-quality products to the automotive industry.”
The hot-dip galvanized sheet steel production facility has a production capacity of 400,000 tons annually. It can produce sheet thickness from 0.4 mm to 2.6 mm and widths of 800 mm to 1,850 mm. Nucor and JFE will each supply an equal amount of substrate to be processed at the new facility.
STALMAX, a manufacturer of fasteners, is investing in a belt furnace for tempering in a protective atmosphere. The provided equipment is designed for hardening fasteners, such as bolts and nuts, intended for the automotive industry. The main element of the line is a belt furnace equipped with a muffle, in which the heat process is conducted in a protective endothermic atmosphere.
The applied design solutions allow for a high evenness of temperature uniformity to be achieved. The automated process of the work of the ATG processing line by SECO/WARWICK, equipped with a weighing system, enables a precise loading of the treated elements on the hardening furnace belt.
STALMAX vice president, Robert Jeż, says, “SECO/WARWICK with their solutions answers real manufacturing needs, and ATG-type line is a guaranteed fulfillment of the industry’s and the clients’ requirements. The partner has not only offered an excellent furnace, but also protected us in case of an unwanted failure. In accordance with individual needs, components of element coding have been introduced and are connected to the alarm base (PLC) and electric documentation of the control system. Such a solution allows to immediately identify the failure and the damaged element.”
Automotive part designs and heat treating processes have undergone many changes over the years, especially the powertrain. By looking back at the progress of these changes, we can learn more about emerging trends in automotive heat treating today.
In this Heat Treat Today Technical Tuesday feature,Bill Disler, president and CEO of AFC-Holcroft, brings his familiarity with big atmosphere carburizing systems and LPC automotive cell carburizing systems and looks at how the evolution of equipment and process requests says a lot about the trends we see today in automotive heat treating.
Although many components undergo heat treatment processes, the powertrain—specifically, gears— typically requires more carburizing time than other automotive parts. Not surprisingly, the powertrain has also seen many changes in heat treatment trends.
Not only have powertrain designs gone through tremendous transformations but so has the equipment being used to process those evolved components. Having spent years on the supplier side of atmosphere furnaces, vacuum carburizing, and gas quench as well as induction systems, I find it interesting to look back at some of the drivers that have helped morph this industry’s heat treat needs.
Traditional Continuous Atmosphere Furnace
Large atmosphere pusher furnaces produced nearly all of the powertrain gears 20+ years ago. Today, cellular low-pressure carburizing (LPC) and gas quench systems carry the load, although the results have not been cost saving. Moving from high volume gas heated carburizing equipment to small batch carburizing in electrically heated furnaces did not reduce utility costs per part; instead, other areas adjusted to compensate. Eliminating the expense of hard grinding transmission gears was an acceptable rationale for this increase in both capital expense and operating costs. Eventually, streamlining the overall gear manufacturing process, combined with locating heat treat within machining lines, produced positive measurable results. Plant traffic decreased, minimizing safety risks. Cooler and cleaner furnace systems were designed. And installations were made easier. Many agreed the changes were justified.
Integrated Vacuum Heat Treat Cells
As we look back, many of these drivers for change proved valid. Others, not so much. In most cases, consumer preference for quiet powertrains necessitates hard grinding of gears. Green is in and talk of the absolute need for zero intergranular oxidation (IGO) in carburized gears has slowed. LPC/Gas post quenched parts are perceived as cleaner and leaner; however, it is often difficult to differentiate green parts from processed parts, so it has become a best practice to add part marking after carburizing and hardening to avoid even the remote risk of sending soft parts down the line to the next stage of manufacturing. Shot peening is still common for strength reasons. The ability to nest large cellular LPC systems within machining has been a success, but rarely are the installations as quick and easy as promised.
Hybrid Furnace Concepts
Conventional atmosphere furnace technology has advanced as well, although at a slower pace, in step with a renewed interest in energy efficiency, particularly in the U.S. where gas is cheap and electric is not. Combustion systems operate cleaner and at much higher efficiency than in the past. Having said that, it is curious how little interest end users have in trading cost-saving gas-heated systems for the easier to install, neater looking electric heating options. In addition, it is no longer common to use water for cooling conventional atmosphere furnace systems as end users do not want to deal with the cost and complications that accompany this option. The market is polarized over this. LPC systems rely on large water volumes for cooling, and they are small batch, electrically heated systems. At the same time, gas quench systems consume huge quantities of water and require giant 300 HP plus motors that are tough to manage in plant power systems.
Flexible and Re-deployable Heat Treat Systems
It is my observation that the automotive market is anticipating the next iteration of heat treat equipment. One type of process or equipment style will not fit all needs, yet all hope for the perfect single part flow solution—an elusive dream due to physics. The cost/time equation still does not balance, and carburizing offers the benefits many manufacturers are looking for, despite the desire to design the process out of practice. Many automotive transmission parts that were originally processed in LPC and gas quenched now use gas nitriding instead, even though gas nitriding is another long process, and nitriding introduces ammonia back into the process—something most automotive plants are not enthusiastic to have in their plants. Two steps forward and one step back.
Repackaging Continuous Furnace Systems
With the widening range of processes and solutions under exploration, as well as ever changing powertrain systems designed to accommodate supplemental electric motors, lighter weights, smaller cars, and larger SUVs, all we can be certain of is ongoing change. I believe that we have witnessed major adjustments in automotive heat treat processing as the pendulum has swung from big, multi-row atmosphere pushers with salt or oil quench to electric-heated cellular LPC and gas quench units. One surprising result has been the resurgence of salt quenching, which controls distortion of high-pressure gas at a much lower cost with less complexity. Salt, like gas, is a single-phase quench media: It does not boil in these processes like oil does, and it can be used at temperatures that support martensitic quench with far less thermal shock and much higher heat transfer than the options. Older processes carry the baggage of tarnished past reputations, but I no longer count them out. Today’s automation, process control technology, and innovation can provide the foundation for brand new concepts, repackaging of older ideas, and hybrids of multiple technologies. Together, these create building blocks that heat treat equipment suppliers will use to meet changing trends in automotive carburizing and heat treatment. It will be interesting to be involved in the journey as these changes take place.
About the Author: Bill Disler is president and CEO of AFC-Holcroft, part of the Aichelin Group located in Vienna, Austria. He is a member of the Board of Trustees -Metal Treating Institute (MTI), and a member of the Board of Advisors at Lawrence Technical University, College of Engineering in Southfield, Michigan. This article originally appeared in Heat Treat Today’sJune 2019 Automotive print edition.
