A North American manufacturer has bolstered its heat treatment capabilities for annealing steel parts after induction hardening. The two-zone belt conveyor furnace shipped to the facility ensures precise temperature control, energy efficiency, and compliance with AIAG specification CQI-9.
“The customer chose to enhance the operating efficiency of the oven with the E-Pack™ Energy Efficiency Package. Depending on utility rates, operating temperature, and weekly usage, customers may achieve significant annual energy savings with this upgrade,” said Tom Trueman, senior application engineer for Wisconsin Oven Corporation.
Tom Trueman Senior Applications Engineer Wisconsin Oven Corporation
Wisconsin Oven Corporation designed the conveyor furnace with the capacity to heat 2,400 pounds of steel per hour from 70° to 350°F with a maximum temperature rating of 500°F and the ability to anneal the components after induction hardening. The recirculation system features a top-down airflow design with a 32,000 CFM blower, with each of the two zones utilizing 16,000 CFM. The temperature for both zones is controlled by a Watlow F4T digital recorder/controller, which provides Ethernet communication capabilities and PID temperature control with adaptive tuning. As a factor in its CQI-9 compliance, a temperature uniformity survey was conducted, documenting uniformity of ±10°F at 350°F with verified part soak.
To maximize energy efficiency, the oven has been upgraded with an E-Pack™ Energy Efficiency Package, which includes 2” thicker insulation in the walls, floor, and roof, as well as variable frequency drives on the recirculation blowers.
The press release is available in its original form here.
The thermal processing industry is a good example of how the on-site production of hydrogen by water electrolysis can be beneficial for many of its processes and for reducing the CO2 of its plants. In today’s Technical Tuesday, David Wolff, industrial sales director at Nel Hydrogen, discusses how, from plasma spray to metal AM binder jet to annealing at rolling mills, industries across medical, automotive, and beyond are looking to water electrolysis for hydrogen production.
This informative piece was first released inHeat Treat Today’sDecember 2024 Medical & Energy Heat Treat print edition.
Hydrogen atmospheres are widely used in high temperature thermal processing, including annealing, brazing, PM, MIM, and binder jet AM sintering, metal-to-glass sealing, and related processes such as thermal spray. Hydrogen helps heat treaters achieve acceptable product characteristics. It’s used as a very powerful reducing agent, and it actively cleans surfaces as compared to inert gas atmospheres which only displace oxygen.
Relative to hydrogen’s use in helping plants decarbonize, it’s a fact that major OEMs buying heat treating services and heat treated products are demanding that their suppliers report their decarbonization progress. To meet the needs, hydrogen generation is becoming ever more compelling to heat treaters to ensure hydrogen for atmosphere needs inside the plant, and to help minimize their carbon footprint.
The Clean Energy Supply Conundrum
Most U.S. heat treating facilities get their atmosphere components delivered by truck. The truck emits CO2 and the hydrogen on that truck is likely “gray” hydrogen made from natural gas. Hence, the carbon footprint from their hydrogen use is notable. Importantly, the electricity grid operators are actively seeking ways to enhance the business success of providers of low carbon electricity. The key issue with those providers — solar, wind, hydro, and nuclear — is that they cannot easily follow the ups and downs of demand. Instead, consumers get electricity from those resources when the wind is blowing, the sun is shining, or the river is high. In the case of nuclear plants, they preferentially run at near fixed output, day and night. They run continuously regardless of demand. As the grid demand is very low at night, they get very low prices for the electricity they generate. They only make money for 12 or so hours a day. That’s why a lot of nuclear plants are threatening shutting down for economic reasons.
Taking Advantage of Low Demand Period Energy Prices for Use During High Demand Hours
Consider this scenario: What if a client with electrolysis capacity to produce hydrogen, such as a heat treater, could buy electricity at lower nighttime prices to make the hydrogen it needs during the day shift for its various processes, perhaps even heating their furnaces? The clean energy provider would be pleased to have more income during its low demand, low price times. The heat treat plant is happy saving money buying decarbonized electricity at low demand prices to make clean hydrogen for its various thermal processes and to operate its furnaces. And, the heat treat company’s OEM clients demanding decarbonization are satisfied, too.
How To Get Started
The scenario described above is a practical and real one for the heat treat industry today. Nel Hydrogen recommends that a heat treat company begin with a plan. That plan may comprise several phases. It’s important to seek out a knowledgeable hydrogen partner in this endeavor to specify exactly what’s needed. For heat treat applications, users generally would want compact equipment, extreme hydrogen purity, load following, near-instant on and instant off, and sufficient hydrogen pressure that make it flexibly suited for a variety of thermal processes, and for hydrogen storage addition at a later time if desired.
Figure 1. Compact hydrogen generators using water electrolysis for thermal processing applications (Source: Nel Hydrogen)
Both batch and continuous processes can be served. Batch processes may benefit from a small amount of surge storage at the outset. By combining on-site hydrogen generation with a small amount of in process hydrogen surge storage if needed, on-site hydrogen generation can be used to meet the needs of batch processes such as batch furnaces and thermal spray. By carefully choosing generation rate and pressure, and surge storage vessel volume and pressure capacity, the combination of generation with surge storage can provide maximum process flexibility while minimizing the amount of hydrogen actually stored.
The presence of a small amount of hydrogen surge storage also protects clients’ parts in case of an electric interruption that stops hydrogen production. The surge storage hydrogen can protect the parts while they cool under a reducing atmosphere.
In practice, specific client priorities such as minimum hydrogen storage, or lowest system capital cost, or highest degree of expandability, or least amount of space occupied, can be met by choosing the specific hydrogen generator capacity and surge storage system employed for any particular production challenge.
Examples of Thermal Processors Producing Hydrogen On Site with Water Electrolysis
Decarbonization will be a near-future requirement as part of the global effort to evolve towards a cleaner, greener world. On-site hydrogen generation in industry makes great sense to align with those initiatives. Right now, the thermal processing industry is experiencing the benefits of producing hydrogen on site for its production processes, and the decarbonization demand will be easier to accommodate with that infrastructure in place.
Here are a few examples of companies performing a variety of thermal processes that have made the decision to use water electrolysis to produce hydrogen on site:
Plasma Spray of Cast Iron Cylinder Liners
One of the most compelling examples has been implemented by two different U.S. automakers to accommodate the increasing use of low-weight aluminum engine blocks in today’s high efficiency vehicles. Aluminum blocks must have a cast iron lining on the inside of the cylinder bore to maximize the durability of the engine. (Older readers may recall the notorious Chevy Vega that used an aluminum engine without a cast iron liner. The author’s wife had one Vega which burned through three engines!)
Figure 2. Plasma torch used to spray-apply metal coatings in additive
manufacturing processes (Source: Shutterstock)
The traditional approach to provide a cast iron liner was to drive a sleeve into the aluminum engine block. However, a new technology has been commercialized by which the cast iron liner is spray-applied using a plasma torch. The torch uses hydrogen and argon gases to add energy and maintain the necessary low oxygen atmosphere. The plasma spray was a new addition to engine production facilities that had not previously been equipped with hydrogen supply and thus elected to generate their own to minimize delivered hydrogen and avoid the need for hydrogen inventory and extensive supply piping.
The electrolyzers recommended for plasma spray applications are compact and produce high purity hydrogen of better than UHP grade at 200+ psig pressure, with less hydrogen stored than would fill a party balloon bouquet. About the size of a washing machine or refrigerator, depending on the model, each unit is low maintenance, compact, quiet, and can be installed nearly anywhere in a facility.
Metal Additive Manufacturing (AM) Binder Jet
One of the most exciting approaches to metal AM is the technology called binder jet, which creates a near net shape part using polymer and wax binders to adhere metal powders. After the part is formed, the binders are chemically or thermally removed. Then the part is sintered to attain near net shape and full part density. Hydrogen is required for the sintering atmosphere to prevent oxidation of the part during the sintering process. Binder jet technology promises to provide for mass production of individually customized parts at high production rates and consequently lower costs than parts produced individually.
Figure 3. Binder jet metal AM parts sintered in a hydrogen atmosphere (Source: Shuttershock)
Many new metal AM production facilities are being established in factories that are not already equipped for the delivery, storage, and internal piping/distribution of hydrogen. As such, many have chosen instead to use zero inventory hydrogen made on site to minimize infrastructure investments. Electrolyzers for small-scale applications requiring up to 230 scf/hr of hydrogen gas at 99.999+ % purity are advised for metal AM. About the size of a large refrigerator, the units require minimal facility floor space, are easy to maintain, and can be installed in any non-classified space. Applications for AM include medical, electronics, industrial, and automotive components.
Annealing at Rolling Mills
Plate and strip metal are processed in rolling mills where the thickness of the metal is reduced by alternating “cold” rolling steps followed by intermediary hot annealing steps. Cold rolling makes the metal more brittle, so it is necessary to have an annealing step following each rolling step. The metal is alternately thinned and then softened for what could be several iterations. Hydrogen is required for the annealing steps to maintain metal surface quality while heated. Because of the periodic market disruptions in delivered hydrogen from plant outages or trucking interruptions, several rolling mills have chosen to generate hydrogen on site to augment or entirely replace their delivered hydrogen supply. The benefits that the plants experience are primarily focused on supply reliability. Of course, they are also eliminating the carbon footprint associated with truck delivery. In this case, the carbon footprint of the generated hydrogen is determined by the particular electricity generating mix that serves the plant site.
Most often at rolling mills, electrolyzers that produce up to 1,140 scf of hydrogen gas at 99.999+ % purity are best suited for the hydrogen requirement. These units replace the need for hydrogen tube trailers or liquid hydrogen storage. They can be installed in the mill or can be containerized outdoors, offering flexible siting and reduced operational safety risks compared to delivered hydrogen.
Figure 4. Steel rolls are heated in an annealing step to soften the metal during production. (Source: Istock)
On Track Towards Decarbonization
Described in the examples above, once the means to generate hydrogen is chosen at a thermal processing facility, the company can move further along the decarbonization journey. This may be to apply a strategy as outlined in the electricity scenario whereby the company takes advantage of low demand rates or institutes an alternative creative idea. Certainly, as more and more clients demand proof that suppliers are reducing their carbon footprint, more strategies will be developed and implemented to serve the thermal processing industry. Simply generating hydrogen on site removes the trucking emissions factor and is a beneficial and practical starting point.
About the Author:
David Wolff Eastern Regional Sales Manager Nel Hydrogen
David Wolff has 45 years of project engineering, industrial gas generation and application engineering, marketing and sales experience. He has been at Nel Hydrogen for over 25 years as a sales and marketing leader for hydrogen generation technologies.
For more information: Nel Hydrogen at sales@nelhydrogen.com.
A major ship builder has acquired a vacuum furnace for the Additive Manufacturing Division at the company’s new Manufacturing Center of Excellence. The single chamber vacuum furnace will be used primarily for annealing powder metal 3D printed parts, with additional capabilities for on-demand tool hardening applications.
Piotr Zawistowski Managing Director SECO/VACUUM Source: SECO/VACUUM
The 3D printing shop and annealing furnace supplied by SECO/VACUUM will enable rapid fabrication of critical replacement parts faster than traditional manufacturing methods, allowing the manufacturer to get ships out of dock and back underway sooner. The Vector furnace is equipped with a 36 x 36 x 48 inch metal hot-zone, a high-vacuum diffusion pump, and a 6-Bar high-pressure argon and nitrogen gas quench.
“To get their 3D operation up and running quickly, we were able to pull off some clever production schedule juggling in order to accommodate their special request for an accelerated delivery schedule,” said Piotr Zawistowski, managing director of SECO/VACUUM.
This vacuum furnace provides a wide range of additional processes, including hardening, tempering, solution heat treating, brazing and sintering, and low-pressure carburizing. Vector produces clean, uniform, high-quality parts with repeatable accuracy and no oxidation.
The press release is available in its original form here.
EBNER Group, a global provider of heat treatment solutions, melting, and casting for the aluminum industry has increased its stake in a furnace manufacturer, including annealing furnaces. GNA alutech inc. produces aluminum melting and holding furnaces, homogenizing and annealing furnaces, and cathode sealing equipment.
Robert Ebner CEO, EBNER Group Source: EBNER Group
“We are excited to announce the full acquisition of GNA alutech inc. and would like to thank GNA’s founder, Ted Phenix, for his vision and leadership in building GNA into a successful company over 41 years. Over the last 5 years I was always impressed by the deep understanding and knowledge Ted was able to share with customers. Our strong professional developed to a strong personal friendship,” said Robert Ebner, CEO of EBNER Group.
EBNER Group provides heat treatment solutions for the aluminum industry with the companies EBNER, ETS, EED, Gautschi, TPS, Hazelett, HPI, and GNA, increasing its stake in the latter to 100%. The acquisition marks the culmination of a five-year partnership between EBNER and Ted Phenix, which began with EBNER Group acquiring a majority stake in GNA in 2019.
The leadership of GNA has been placed in the hands of Kaleb Wright, president of business development, and Chantal Coupal, president of operations.
Pictured: Chantal Coupal, president of operations of GNA alutech, and Kaleb Wright, president of business development of GNA alutech
The press release is available in its original form here.
An aerospace, industrial gas turbine, and automotive market leader has expanded its heat treatment operations with a recently purchased air atmosphere furnace. Connecticut-based Doncaster Precision Castings will use the new furnace to support annealing, tempering, and heat treatment of steel and castings.
Doncaster Precision Castings previously received a similar model for use in its heavy-duty industrial processes within the aerospace and automotive sectors. The furnace, supplied by L&L Special Furnace, has a maximum temperature of 1850°F (1010°C) and a capacity to handle a typical load weight of 2,000 pounds.
The press release is available in its original form here.
Roller hearth furnaces are known as the work horses of the heat treating industry. Though they may be common, these furnaces still hold some surprises — namely, their diverse applications, potential to be fully automated, and long life span. Five industry leaders provide insight into the current furnace features and how to optimize them for annealing heat treat. As you read, notice the different emphases each expert addresses.
This Technical Tuesday was originally published inHeat Treat Today’sJanuary/February 2024 Air and AtmosphereHeat Treatprint edition.
Application Determines Customizable Furnace Features
This type of furnace is highly customizable, and, as Tim Donofrio, VP of Sales at Can-Eng Furnaces International explains, knowing the application will determine furnace features.
What Features Do You Offer on Your Roller Hearth Furnace for Annealing Various Materials?
Tim Donofrio Vice President of Sales Can-Eng Furnaces International, Ltd. Source: Can-Eng Furnaces International, Ltd.
The following is based on roller hearth furnaces operating at or above 1400°F.
Annealing furnace features depend upon the material being processed and the metallurgical process being carried out. They can be provided with a wide variety of features for preheating, annealing, slow cooling, oxidizing or bluing and accelerated cooling.
Preheating features include direct or indirect heating applications, under air or controlled atmospheres. Preheating in some cases requires features for burn-off of residual blanking fluids prior to entry into the critical anneal chamber and as such, the off -gas must be appropriately addressed.
Annealing can be a direct or indirect heating application using natural gas, blended hydrogen/natural gas, and electrical energy sources. Process protective atmospheres include N2, Exothermic gas, Endothermic gas, N2 + H2, and H2. In some cases, process atmospheres must be carefully controlled and monitored to very low O2 PPM levels to ensure correct oxides are formed or, alternatively, a bright oxide-free finish is achieved, something very critical when annealing electrical steels for transformer core and motor annealing. Today we see a rise in the use of roller hearth furnaces for the manufacture of transformer core and motor cores, processing electrical steels and amorphous metals. This is largely a result of the electrification of the world.
Post-annealing cooling and bluing are paramount to the process success. In most cases, cooling and soaking stages are provided through the integration of direct and indirect cooling methods that include air, water, and externally chilled atmospheres that can be directly injected into the furnace system and recirculated.
How Is Your Roller Hearth System Unique?
Roller hearth furnaces are the work horse of the industry; they are used for a variety of other heat treating applications. For example, roller hearth furnaces can also be used for low temperature curing, tempering, and aluminum heat treating applications. These lower-temperature roller hearth furnaces do not operate above 1400°F and are built with different fabrication and refractory standards. Of course, additional high temperature applications include neutral hardening, case hardening, carbonitriding, isothermal, and spheroidizing annealing and normalizing.
Roller hearth furnace
Can-Eng Furnaces International offers roller hearth annealing furnaces that meet the stringent demands of today’s manufacturers where safety, product quality, and equipment reliability are at the top of our engineers’ minds during design and development. Can-Eng has developed a strong user base that has benefited from design features that ensure tight temperature control and repeatable thermal profiles while also tightly controlling process atmospheres. This is achieved by integrating some of the best available heating and atmosphere technologies while being combined with state-of-the art automation and robotics to deliver the lowest cost of ownership processing systems to our clients.
What Are Best Practices for Training In-House Operators on Roller Hearth Annealing?
Our company promotes hands-on and classroom multi-level training of operators, maintenance staff, and engineers. This provides a complete and full understanding of the equipment and the opportunity to train within the company for future talent development.
What Are the Furnace’s Operational Advantages?
Can-Eng integrates operator-friendly features that contribute to the reduction in energy and atmosphere consumption while minimizing the carbon footprint and emission levels. Combined with on-board system diagnostics, monitoring, and data collection, these allow for minimal operator involvement.
What Is the Most Common Heating Method?
Today, the most common methods are both natural gas and electric. However, Can- Eng works to integrate features that provide our partners with the benefits of reusing waste heat sources such as flue gases within the system or facility to improve operating efficiencies.
What Are the Challenges in Operating This Type of Furnace?
These (atmosphere control, maintenance, uptime, and temperature control) are all typical challenges that are addressed in design. The key is to design flexibility, ease of use, and operator-friendly features to avoid problems in the future when the client wants to process different products in a different way.
Training and Maintenance To Optimize Uptime
Bob Brock, sales engineer at AFC-Holcroft, emphasizes the importance of training and maintenance to best operate the roller hearth system.
What Features Do You Offer on Your Roller Hearth Furnace for Annealing Various Materials?
Bob Brock, Sales Engineer, AFC-Holcroft
Roller hearth furnaces are designed to provide greater uptime, ease of maintenance, and trouble-free operation and are always custom-designed to meet our clients’ specific processing requirements.
Modular designs are available to accomplish basic heating, holding, and cooling segments but also to incorporate burn off, cyclic spheroidizing, bluing, fast cooling, and blast cooling under controlled atmospheres ranging from Endothermic to Exothermic gases, nitrogen, hydrogen, and products of combustion. A broad range of material handling automation and control platforms providing total data monitoring, controlling, tracking, and acquisition capability are also offered.
How Is Your Roller Hearth System Unique?
AFC-Holcroft has designed, built, and commissioned hundreds of roller hearth manufacturing, and fi eld support teams have extensive knowledge and experience with annealing, isothermal annealing, normalizing, carburizing, and solution and aging processes for ferrous and nonferrous applications. This expertise has well positioned us in the roller hearth furnace market.
What Are Best Practices for Training In-House Operators on Roller Hearth Annealing?
3D image of annealing roller hearth furnace Source: AFC-Holcroft
We use a two-step approach when training operators on our equipment. First, hands-on training provides the best opportunity to learn equipment operation, startup and shutdown procedures, as well as maintenance tasks. Second, we follow up hands-on training with classroom discussions to further the operator’s knowledge of equipment and the use of our operating manual. Our two-step approach arms our client operational team with the confidence and knowledge they need to be successful from day one.
What Are the Furnace’s Operational Advantages?
Roller hearth furnaces are designed and built with longevity and uptime in mind. From our integrated preventative maintenance reminders, robust construction, and user-friendly controls, it’s not uncommon to see our equipment still in operation for 50 years or longer.
What Is the Most Common Heating Method?
Natural gas continues to be the predominate heating source in North America, although we have seen an increased interest for alternate heating sources like electric, hydrogen, and bio over the last several years. We anticipate this trend to continue as companies invest in minimizing their carbon footprint, and can provide clients with carbon footprint analysis and operational costs on our equipment.
What Are the Challenges in Operating This Type of Furnace?
Routine equipment maintenance is key to operational uptime. AFC-Holcroft offers a wide range of preventative maintenance programs for our clients. The services can be customized to include hot and cold inspections, thermal imaging, burner tuning, and equipment optimization analysis.
Consistency Is Key To Increase Furnace Life
Given that the roller hearth furnace is a continuous system, understanding how the system works and operating at the correct, consistent rate is crucial for success. Jacob Laird, mechanical engineer at Premier Furnace Specialists, dives in deeper.
What Features Do You Offer on Your Roller Hearth Furnace for Annealing Various Materials?
Premier Furnace Specialists (PFS) is capable of building annealing furnaces for a wide range of workloads. We have built small batch normalizing furnaces with simple manual roller hearths, as well as 120+ foot long fully automated annealing roller hearths with multi-zone control and automatic load staging. We also offer a variety of controlled heating/cooling systems and atmosphere generators and gas dryers to provide optimal annealed part quality. Controlled cooling systems may include: radiant tube indirect cooling, atmosphere forced convective cooling, and post-process forced convective cooling with ambient air.
How Is Your Roller Hearth System Unique?
Jacob Laird Mechanical Engineer Premier Furnace Specialists, Inc./BeaverMatic Source: Premier Furnace Specialists, Inc./BeaverMatic
One of the unique uses for annealing furnaces is for soft magnetic steel alloys aft er they have been cold worked or formed. This is often used for products inside electrical equipment such as electric motors or transformers where grain growth and residual stresses may affect the magnetic properties of the material. The most cost-effective process for this heat treatment is through a continuous atmosphere with a reducing atmosphere (often provided by a lean Exothermic gas atmosphere). For this process, the atmosphere requires a specific range of hydrogen alongside a controlled heating and cooling recipe with multiple stages.
Premier Furnace Specialists also provides the accessory equipment that can be required for a complete annealing operation. We will build the Exothermic gas generators (rich and lean), Exothermic gas dryers (air and water cooled), nitrogen/methanol/hydrogen (or other bulk atmosphere) gas trains/delivery systems, water recirculation and convective cooling systems, load management equipment/software, and any other required pre/post processing equipment right here at our facility in Farmington Hills, MI. By building all of the ancillary equipment alongside the annealing furnace, it allows the client to benefit from installation of the entire system at once, identical spare parts across all pieces for easier maintenance, identical control systems with consistent terminology for ease of operator training, a single contact source for all engineering assistance and troubleshooting, as well as a service department capable of quickly responding to requests for both our equipment and any other equipment the customer may already have.
A 16 ½ ft. wide x 9 ft. high x 125 ft. long roller hearth furnace with four
heating zones and two cooling zones. Maximum temperature of 1500°F,
nitrogen gas atmosphere.
Concerning efficiency, combustion heating systems can be customized with preheat and recuperation systems, recuperative or regenerative burners, or multi-legged radiant tubes to minimize gas train complexity and NOx emissions while maximizing efficiency and profitability. Electrically heated systems can be equipped with SCR power controls which minimize temperature swings at setpoint, provide optimum work chamber uniformity by eliminating heat surges, and conserve energy by reducing current draw at operating temperature. Processes can also be equipped with digital atmosphere analyzers, flowmeters, and gauges capable of displaying the remote equipment conditions at localized control stations or on mobile devices.
What Are Best Practices for Training In-House Operators on Roller Hearth Annealing?
Specifically for roller hearth furnaces, operators and maintenance personnel must understand the rollers and drive systems to ensure products continue processing at a correct rate. For continuous systems in particular, drive failures may result in the loss of large volumes of product that often cannot be recycled as well as lengthy purge/shutdown/ startup times.
As an example, chain and sprocket driven rollers just only be locked down on the drive side of the furnace so that thermal expansion allows them to grow on the idle side. Otherwise, the sprockets may walk out of alignment and cause a multitude of long and short-term issues such as rollers seizing and warping, drive faults, load crashes, and timing issues between multiple driven segments.
Th e best practice would be for operators to be trained to understand how major components of the furnace may affect the part quality. This knowledge will also assist in troubleshooting issues that may arise and correcting them before they become worse.
What Are the Furnace’s Operational Advantages?
Roller hearth furnaces can handle a large assortment of part sizes by varying the roller diameters and spacing between them. For small parts, the rollers can be used to drive a mesh/cast belt or convey trays. For long parts, they can rest on the rollers with multiple support points. The bar, pipe, and tubing industries use incredibly long roller hearth furnaces while many industries process heavy wire coils in them. By segmenting the roller drives and utilizing VFDs or servomotors, roller hearth furnaces become capable of staging loads, customizing processing times, and oscillating at temperature to prevent rollers from warping under heavy loads.
What Is the Most Common Heating Method?
Premier has seen a steady demand for gas fired roller hearth equipment, but most quotes nowadays also request pricing for an electric alternative to compare against. The end user’s facility location and local utility regulations are typically the deciding factor.
What Are the Challenges in Operating This Type of Furnace?
A common challenge for any continuous furnace is maintaining consistent production and limiting shutdowns or idle periods. Large continuous furnaces burn up a significant amount of energy even when idling, so any time spent not in production becomes costly. Even when the equipment sits powered down, start-up procedures including insulation dry-outs, inert gas purge requirements, and atmosphere seasoning can take days until production can resume.
However, once consistent production is maintained, part quality, part consistency, and energy efficiency can be noticeably better than batch equivalents.
Issues can be avoided by noting areas of concern as they arise and following routine maintenance procedures until scheduled annual or biannual shutdowns (often around holiday breaks). Then additional time can be given to address potentially major issues with service visits and inspections by OEM service teams.
An Eye on Energy
Reiterating the customizable nature of this style furnace, Ryan Sybo, project manager at SECO/WARWICK USA, comments on the attention on energy usage that clients and suppliers share.
What Features Do You Offer on Your Roller Hearth Furnace for Annealing Various Materials?
Ryan Sybo, Project Manager,
SECO/WARWICK USA
We offer a wide variety of options as a custom furnace company. We can tailor the furnace to meet the unique needs of individual clients. On annealing furnaces specifically, we offer a controlled cool chamber and a steam blue chamber.
Individual roll sections can be started, stopped, reversed, oscillated, and run at the same speed or at different speeds for maximum process versatility.
Atmosphere integrity is assured through welded gas-tight shells, sealing doors, and pressure control systems.
Fast and slow heating and cooling rates are possible. Plus, pre-heating can be employed.
Post-heat treating processes like steam blue are possible.
Furnace doors are specially constructed and insulated for operation within the temperature zones in which they are located, minimizing stress and warpage caused by temperature differences.
Heating and cooling sections incorporate dependable, high-quality components for long-life operation.
High-speed transfer between sections allows closely spaced workloads or work trays with separation during transfer through doors, assures optimum use of hearth space, and minimizes atmosphere mixing. All door openings can be adjusted to workload heights, permitting faster operation and minimizing atmosphere mixing.
How Is Your Roller Hearth System Unique?
The controlled cool chamber offers precise control of the cooling rate. The steam blue chamber is used to develop a blue oxide, Fe3O4, for electrical insulation characteristics.
Our company has been designing and manufacturing furnaces for over 123 years, and we have been exploring new refractory materials and more energy-efficient burners and recuperators, as well as offering state-of-the-art atmosphere controls.
What Are Best Practices for Training In-House Operators on Roller Hearth Annealing?
Our furnaces are all built to the latest NFPA 86 and OSHA standards, however, safety training like HMI is also important.
What Are the Furnace’s Operational Advantages?
Several of this furnace’s operational advantages include:
Continuous Unlimited Work Flow: Provides better efficiency than batch processing since the workload can continuously feed into the furnace.
Quick, Easy Installation: For SECO/WARWICK USA, these are normally built at our manufacturing facility and tested, then disassembled into sections to fit on a truck or shipping container.
Long Life: A 40-year lifespan is typical. Less stress on furnace components from faster or constant temperature recycling when compared to belt, chain, or pusher units.
Smaller Factory Footprint: Manufacturers can save about half of the floor space than with multiple batch units.
Flexible Operation: Roller drives can be slowed, sped up, or stopped. Process parameters can be changed, any atmospheres can be used from H2 to air, plus door separations can be used between sections for better separate processing functions.
Lower Production Costs: Each furnace is custom-designed for continuous operation at the desired operating temperatures. Less waste from heat-up and cool-down cycles used in batch systems and in-line processing makes energy recuperation easier to integrate.
What Is the Most Common Heating Method?
Gas fired is the most common, however, we have been seeing a lot of inquiries for electrically heated roller hearth furnaces.
Geographic location is also a big determining factor because some areas have more access to natural gas that can offer reduced operating costs.
What Are the Challenges in Operating This Type of Furnace?
There are no challenges in operating this type of furnace due to our custom-engineered, user-friendly automatic furnace controls. Preventative maintenance can be included in our control systems to remind operators and maintenance personnel to service the equipment. Furnace data and alarms are logged and ready for download and review.
Leveraging Efficient Designs To Process Heavy Workloads
Kelley Shreve, general manager at Lindberg/MPH, hones in on the significance of roller hearth furnace workload capacity as a lynchpin to heat treat operations.
What Features Do You Offer on Your Roller Hearth Furnace for Annealing Various Materials?
Kelley Shreve General Manager Lindberg/MPH Source: Lindberg/MPH
Our roller hearth furnaces are designed to meet the need for accurate, consistent, and efficient processing of heavy workloads. Features include a sturdy roll design for smooth load motion, high-efficiency heating systems for rapid heat transfer, integrated control systems for accuracy of operation and ease of troubleshooting, and material handling systems that simplify operation. Together, these features provide furnaces that will make operations more competitive.
How Is Your Roller Hearth System Unique?
What separates Lindberg/MPH from competitors is our ability to take standard designs and customize them so they are tailor-suited to meet the exact client specifications and floor plans.
Extensive experience in ultra-clean heat treating helped us improve roller hearth equipment as well. Traditionally designed furnaces have transfer sections open to air, which allows rapid heat loss and causes scaling or discoloration of the work. Our proven design shields the work with a directed flow of protective atmosphere through double-door transfer sections. This also ensures isolation of furnace zones that must not be cross-contaminated. An independent, high-speed roll system minimizes transfer time and heat loss. The sight-ports allow direct viewing of work-in-process for easy troubleshooting. The result is clean, consistent work.
What Are Best Practices for Training In-House Operators on Roller Hearth Annealing?
Lindberg/MPH offers complete installation packages which include installation, startup, and training. In-house operators are fully trained on all aspects of operations while our service technician is present.
What Are the Furnace’s Operational Advantages?
Our roller hearth furnaces combine the latest technology in process controls, atmosphere systems, and material handling systems. These furnaces are designed to carry very heavy workloads at high production rates at the lowest possible operating cost. Other advantages are that a roller hearth can be designed to run a multitude of different processes as required.
What Is the Most Common Heating Method?
Roller hearth furnaces can be supplied with either gas fired or electric heating. Gas fired Single End Recuperated Tubes (SERT) provide economical, rapid heating. Electric heating offers reliable, low-maintenance operation using elements tailored to atmosphere application.
What Are the Challenges in Operating This Type of Furnace?
Annealing produces
parts with reduced
hardness and a uniform
microstructure as a
preparation for further
processing. The furnace
has a high-heat section
followed by a controlled
cooling module.
Endothermic, Exothermic,
and nitrogen-methanol
atmospheres are typically
used.
A challenge for this type of furnace is proper maintenance. Operators should manage this challenge by monitoring the preventative maintenance (PM) features and indicators that are available. Setting in place and following a regular PM schedule is going to help ensure the equipment operates dependably and problem free.
In December 2022, the first HIP batch on Latin American soil was performed. The journey to success in HIP, as any HIP user will agree, is a bumpy road. What are the challenges that aerospace manufacturers with in house heat treating should be aware of when considering HIP processing? Learn how HT-MX Heat Treat & HIPing — the heat treater who ran the first HIP batch in Latin American history — navigated the transition from small tooling jobs to HIP processing for aerospace parts.
Read the English version of the article below, or find the Spanish translation when you click the flag above right!
This original content article, first published in English and Spanish translations, is found in Heat Treat Today's March Aerospace Heat Treatingprint edition.
Writing this story as the first Latin American company to offer Nadcap accredited hot isostatic pressing brings a flood of memories and images to mind. HT-MX’s beginnings were simple, but also filled with challenges, failures, and lessons. When the company began, we were certain that, though small, we were still a “heat treat plant” and not just a shop.
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Being located in Mexico means that there were large companies with headquarters located far away — potential customers — that would be deciding on their heat treat supplier close to their location. We worked hard to be and to present ourselves as being very professional. But a lesson soon learned was that achieving trust with partners takes a lot more than a good speech and a clean plant.
Unsurprisingly, the first jobs were simple tooling work, like quench and tempering tooling and carburizing gears. A junior engineer and I would drive around in my old hatch-back to local machine shops and pick up a small shaft or gear and bring it back to the plant. We would get so excited when we got the case depth right.
With minimal resources, we decided to complete quality control ourselves. We became friends with a quality manager from a local company, and he came over to help on weekends and after 6:00pm until the audit date came. His knowledge is still in use at HT-MX to this day. I remember celebrating with a “Carne Asada” (a Mexican style barbecue) when we finished that first audit, thinking we had just made a huge step forward, not realizing how far away we still were from our vision.
HT-MX Team
Source: HT-MX Heat Treat & HIPing
But as time passed, we turned our attention to the aerospace industry in Chihuahua, a city with four OEMs. We received the AS9100 certification and started working on Nadcap accreditation. This required time, but by then, a pretty strong engineering team was in action, and successfully obtained Nadcap accreditation in late 2019. Again, we celebrated with a Carne Asada, this time, with a better understanding on where we were and what future challenges we needed to face.
Taking On Hot Isostatic Pressing
HIP system at HT-MX
Source: HT-MX Heat Treat & HIPing
The pandemic hit. Boeing’s 737 Max crisis continued to impact the industry. Moving into aerospace was slow with limited volume, especially compared to what we had seen in the automotive and oil and gas industry. But by now, international companies were more willing to transfer heat treat operations to Mexican suppliers, and we were ready, beginning with running aluminum batches, precipitation hardening, annealing, and other standard processes. It was during this early start to serve the aerospace industry that we heard about hot isostatic pressing (HIP).
Around 2019 during an aerospace cluster event, an OEM with a local presence approached us with their HIP requirements. I had only heard of HIP, but I was immediately interested — until I found out how much one of those machines cost!
But good financing through government programs helped make this HIP project a reality. Timing was not the best, as the federal election in Mexico caused a temporary Mexican currency depreciation, handicapping the project at its beginning.
Getting the proper certifications and validations proved to be a long and complex process, too. Theoretically, we knew what to expect, in terms of getting the Nadcap checklist approved, but the reality was a little different. Gaining Nadcap certification slowly builds a certain culture into any company in its day-to-day activities. Translating that culture into a completely different business unit, new crew, and new process proved to bring its own challenges.
HIP Challenges: Pressure, Temperature, Thermocouples, and Argon Supply
Heat treating usually handles temperature, atmosphere control (or lack of), and regular traceability requirements. HIP, however, adds a few new dimensions to what we usually see: internal pressure, very high temperatures — up to 3632°F (2000°C) — and argon supply. It was the first time HT-MX dealt with a process that incorporated up to 30,000 psi and also used a lot of high purity argon.
Pressure has its own challenges, though the HIP press takes care of those challenges. Still, the internal workings on these kinds of presses are fundamentally different than that of a regular heat treat furnace. Yes, you need to heat it up, but apart from that, it’s not even a furnace but a press. Understanding how the machine works, what happens inside with all that pressure, how it affects the components undergoing hot isostatic pressing, and how it affects the baskets you’re using is a critical learning curve.
High temperatures change everything about running these types of cycles. We work with metals, which means temperatures range between 1832°F and 2372°F (1000°C and 1300°C). This has an impact on thermocouple selection, calibration, and more; with the company’s thermocouple product suppliers based in the U.S., this entails more challenges and extra costs. I have lost count on those urgent same-day trips to the border to retrieve critical spares in time. It’s an 800-km/498-mi roundtrip! We have fortunately found a great supplier that has offered the technical feedback we needed, and we have started to finally understand and control our thermocouple consumption. Although, I must be honest here, we still have a lot to learn in this aspect.
Then, there’s the argon supply. HT-MX never expected it to be a challenge, but it turns out getting the proper supplier — one that understands the requirements and is willing to work with you from validation to production — is key. You might be able to start your validation process using argon transported in gas containers but eventually you will need to switch to liquid argon. That proved to be more difficult than expected. There are not many projects requiring these kind of alliances locally. Getting the right supplier was key and more of a challenge than expected. And then came the lessons on efficiently using the liquid argon, avoiding excessive venting of the tank, and being all around smart with the HIP schedule. This has been a constant learning process, one that has high costs.
Final Hurdles: Certifications, Current Events, and Energy Costs
Once our company had the Nadcap certification, we still needed to get the OEM’s approval for the HIP process, then the approval for the specific version of the HIP process, and then the actual approval for the part numbers.
These approvals were handled by the headquarters’ engineering department and not locally. It was a time-consuming process, with several test runs, lab testing, multiple audits, visits, and more testing, etc. And while all of this was happening, we still had to design the operation, locate critical suppliers not available in Mexico, create alliances with suppliers, etc. Writing this down in a few lines makes it seem simpler and quicker than it really was.
Additionally, in instances like this, Mexican companies, especially small ones, face much more scrutiny than U.S. or European-based companies, and must prove themselves in every single step. It makes sense, even if it feels a little unfair, as HT-MX had no proven track record of high tech processes such as HIP. It does cost extra time, extra care, and sometimes extra testing, but it is the reality we face and we must overcome the extra hurdles.
While navigating HIP approval, the pandemic hit. Months later, the war in Europe began with significant impacts on the cost of energy. Our main clients were high volume and low margin, and with energy prices rising, our competitiveness began to diminish. To adapt and evolve, we decided to add some smaller furnaces for smaller parts, invest in training and increased sales efforts, and focus on AMS/Nadcap-based customers, letting go of major clients. Slowly, things began to turn around.
The First Official HIP Batch in Latin America History
In December 2022, HT-MX ran the first official HIP batch in Latin American history. It was a long time coming. I always thought that running that first batch would feel like reaching the Everest summit. When the day came, it just felt like reaching Everest’s base camp. We still have a long way to go to be truly an established HIP supplier. Now, it’s back to climbing and shooting for that summit, that summit that will perpetually precede the next summit.
There are still several challenges: stabilizing new processes and improving established ones. But I am confident we will move forward in this new stage. And I am so looking forward to the next Carne Asada.
About the Author: Humberto Ramos Fernández is a mechanical engineer with a master’s degree in Science and Technology Commercialization. He has over 14 years of industrial experience and is the founder and current CEO of HT-MX Heat Treat & HIPing, which specializes in Nadcap-certifi d controlled atmosphere heat treatments for the aerospace, automotive, and oil and gas industries. With customers ranging from OEMs to Tier 3, Mr. Ramos has ample experience in developing specific, high complexity secondary processes to the highest requirements.
Welcome to Heat TreatToday's This Week in Heat TreatSocial Media. You know and we know: there is too much content available on the web, and it’s next to impossible to sift through all of the articles and posts that flood our inboxes and notifications on a daily basis. So, Heat TreatToday is here to bring you a hot take of the latest compelling, inspiring, and entertaining heat treat chatter from the world of social media.
Today, check out some posts on everything from a new design to an interactive periodic table to ways to shore up your heat treat knowledge. Don't forget to thank an engineer for Engineer Appreciation Week!
Check out a winner from the Metal Powder Industries Federation 2022 PM Design Excellence Awards Competition. This device is used in laparoscopic surgeries! In order to make the curved jaw piece needed for the instrument, the powder metallurgy metal injection molding process was used. Take a look at this piece from all angles with the video below.
2. Continuing Education
Each of these posts brings an educational aspect for you in your heat treat knowledge base. Something new or something to refresh those brain cells, take some learning moments with these posts.
7 Components To Think About with an Industrial Oven Purchase
DFARS Compliance, Free eBook
Preventing Refractory Anchoring System Failures
Advancing 3D Printed Metals with HIP
Interactive Periodic Table 2.0
3. "Molten" Videos
Too hot to handle? We think not. Check out some of these action shots.
4. The Reading (and Podcast) Corner
Time to take your afternoon coffee and read or listen to a few technical pieces from around the industry, or put on an episode of Heat TreatRadio to enjoy as you commute home!
Here's a recent edition from expert Mike Mouilleseaux on underrated heat treat processes.
With a nod to engineering week, this article delves into categorizing things. "Art or Engineering" explores how to think about products, maybe stretching to think differently about labels applied to things.
5. Engineer Appreciation Week
Spreading the love this week for the engineers among us. Thanks for everything that you do!
6. Updating the Office Space!
This office model might be something you want to incorporate? Looks like some great spots to go over the heat treat paperwork and take the calls.
What process holds a soft spot in your heart? Tempering or annealing? For Valentine's Day, turn up the heat -- errr heat treatments -- with this look at the differences in tempering and annealing! Heat TreatToday has resources for you to spark some thought and learning on these processes.
Sentiments and strong feelings can certainly be heightened this Valentine's Day. While tempering and annealing may not lend themselves easily to the holiday, we hope you enjoy a bit of a nod to the day in our headings below. Make use of the Reader Feedback button, too, and keep us in the loop with questions and comments on what heat treatment you love.
Problem with Annealing? Get to the Heart of the Issue
An automotive parts manufacturer was running into problems with cracking parts. The variable valve timing plates were returning from heat treatment with this problem. To determine why those parts were cracking after the annealing process, an investigation was launched by metallurgists at Paulo.
The presence of nitrogen combining with the aluminum already present in the particular steel being used was forming aluminum nitrides. What could be done? Read more in the case study article below to find out a workable solution that allowed the annealing to create a crack-free product.
Induction, Rapid Air, Oven and Furnace Tempering: Which One do You Love?
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This article gives some perspectives, from experts in the field, on what kinds of tempering are available and for what the processes are used.
Hear from Bill Stuehr of Induction Tooling, Mike Zaharof of Inductoheat, and Mike Grande of Wisconsin Oven with some basics and background information on tempering. Those reasons alone make this resource helpful with information like this: "tempering at higher temperatures results in lower hardness and increased ductility," says Mike Grande, vice president of sales at Wisconsin Oven. "Tempering at lower temperatures provides a harder steel that is less ductile."
More specific in-depth study is presented as well. The Larson-Miller equation is considered, and the importance of temperature uniformity is emphasized. Read more of the perspectives: "Tempering: 4 Perspectives — Which makes sense for you?"
Cast or Wrought Radiant Tubes in Annealing Furnaces - is Cheaper Really What to Fall For?
Marc Glasser, director of Metallurgical Services at Rolled Alloys, takes a look at radiant tubes. He particularly discusses the cast tubes and wrought tubes. For use in continuous annealing furnaces, there are several factors contributing to choice of radiant tube type.
Marc says, "Justification for the higher cost wrought alloy needs to take into consideration initial fabricated tube cost, actual tube life, AND the lost production of each anticipated downtime cycle as these downtime costs are often much more than material costs." He probes into areas that may not be considered when thinking of all the costs involved. Read more of his article "Radiant Tubes: Exploring Your Options."
Tempering Furnaces: Improvements are Thrilling
The expert behind this piece shows the importance of tempering, particularly in automotive fastener production. Tim Donofrio, vice president of sales at CAN-ENG Furnaces International Limited examines what's working in the tempering furnaces. The products are meeting and exceeding expectations.
To wrap up this Technical Tuesday post on tempering and annealing, head over to this additional resource to round out the scope of each process. "What is the Difference: Tempering VS. Annealing" gives a summary perspective on the heat treatments discussed above.
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There are many radiant tube options on the market, so which one is best for your furnace and your budget? In this column that compares radiant tubes in carburizing and continuous annealing furnaces, discover how two major types of radiant tubes stack up.
Marc Glasser, director of Metallurgical Services at Rolled Alloys, investigates more deeply the two choices. This Technical Tuesday discussion on radiant tubes options will be published inHeat Treat Today'sFebruary 2023 Air & Atmosphere Heat Treating Systems digital edition.
Introduction
Marc Glasser Director of Metallurgical Services Rolled Alloys Source: Rolled Alloys
Radiant tubes are used in many types of heat treating furnaces from carburizing furnaces to continuous annealing of steel strip. Generally, a heat treater has three options for radiant tubes: cast tubes, wrought tubes, and ceramic silicon carbide tubes. Silicon carbide tubes are rarely used by heat treaters, so this article will not delve too deeply into this option. Suffice it to say, ceramic materials can often handle much higher temperatures at the expense of ductility; ceramics are more brittle than metals, making them prone to failure from the small impacts, so metal cages are sometimes fabricated to protect them. Most of the tubes being used today are cast radiant tubes. With new casting technology — primarily centrifugal casting — thinner tubes are being cast at a lower cost, which then results in a shorter life.
The primary factors for choosing radiant tube material are tube temperature and carbon potential of the furnace atmosphere. Cost-benefit analysis should also be considered. There are multiple applications for radiant tubes, including carburizing furnaces, continuous annealing furnaces for steel sheet galvanizing, steel reheat furnaces, and aluminum heat treating. This article will explore two of the aforementioned radiant tube options, specifically for carburizing and continuous annealing furnaces.
Radiant Tubes for Carburizing Furnaces
Gas carburization is traditionally performed between 1650°F and 1700°F at a carbon potential of 0.8% approximating the eutectoid composition. In today’s competitive environment, more heat treaters are increasing temperatures to 1750°F and pushing carbon potentials as high as 1.6% to get faster diffusion of carbon while spending less time at temperature. INCONEL® HX (66% Ni, 17% Cr) has been a common cast alloy seen in carburizing furnaces. This alloy is regularly selected for its resistance to oxidation and carburization up to 2100°F. Super 22H is more heavily alloyed than HX and is seeing more use as carbon potentials increase but at a premium price. With advances in centrifugal castings, cast tube wall thicknesses have decreased from 3/8-inch to 1/4-inch. Some heat treaters have shared that this decrease in wall thickness has also led to shorter tube life.
Fabricated and welded radiant tubes in alloys 601 and RA 602 CA® have been tested in industry. When tested, these wrought alloys were fabricated to have a wall thickness of 1/8-inch. At the extremes, tubes fabricated from 601 only lasted 50% as long as cast HX. Historically, HX tubes have been approximately 33% higher in cost than that of 601 and utilize heavier 3/8-inch walls. A little-known fact is that by switching to a thinner wall cast tube, the life drops by 50%. By switching to 1/8-inch wall thickness, RA 602 CA tube life has been extended to eight years or more, while running at 1750°F and up to 1.6% carbon potential, at just a 33% premium over cast HX. Life cycle data are presented in Figure 1.
Figure 1. These life cycle comparisons were done in carburizing furnaces only. In non-carburizing furnaces, justification of alloy selection is dependent on actual operating conditions and each individual operator’s own experience. Source: Rolled Alloys
Radiant Tubes for Continuous Annealing Furnaces
In the area of continuous annealing, the cast alloy of choice is HP/HT (35% Ni, 17% Cr, 1.7% Si, 0.5% C). Here again, this casting has been compared to 601 and RA 602 CA, with the same results. The total life data from these trials are also incorporated into Figure 1. During the collection of this data, there has been no effort to measure the actual tube temperature, so the effect of tube temperature is not clearly defined. In these continuous annealing furnaces, it has been reported that the tubes at the entry end are subject to more heat absorption as burners are firing more due to the continuous introduction of cold material; in trials, the operators have not kept adequate documentation of specific tubes, making justification more diffcult.
Justification for the higher cost wrought alloy needs to take into consideration initial fabricated tube cost, actual tube life, AND the lost production of each anticipated downtime cycle as these downtime costs are often much more than material costs. Only individual fabricators can determine these costs.
The Economics
Table 1 Source: Rolled Alloys
Table 1 above shows the economics of metal alloy choice. To properly interpret, understand that the costs are not actual, but rather relative to 601, so a round number of 1000 was used. With a 30% greater cost of cast tubes, that translates to a relative cost of $1300. The annual cost is the amortized cost over the life of the tube. The total eight-year cost is the relative cost times the number of tubes that would have to be purchased to obtain the life cycle of one tube of the longest-lasting material over its full life cycle.
Missing in this analysis is the additional cost of downtime and lost production. For the replacement of radiant tubes in a carburizing furnace, this typically entails a full week to turn a furnace off, allow it to cool, replace the tubes, and then heat it up again. Many heat treaters do not consider this, and therefore it is a hidden cost. Even without the downtime being considered, by examining the total cost of materials (including replacements) compared to the longest-lasting tube, it turns out that the most expensive tube is the cheapest tube. The obstacle to overcome is whether the heat treater is willing to wait eight years to realize these cost savings.
There can be additional factors to consider. With improvements in the efficiency of casting, the actual costs of the thinner wall casting may be somewhat less, but to match the overall cost of the longest-life material, it would have to be less than half the expected cost. As better, more expensive cast alloys become accepted and actual life data becomes available, these more costly alloys can be added to this table for comparative analysis, too.
This same method of analysis can be applied to radiant tubes for continuous annealing furnaces, but more details will need to be added including furnace position. Different alloy candidates will have to be put to the test in actual operations, carefully document what alloy is in what position or location, and when it gets changed out. This becomes quite cumbersome when annealing furnaces (depending on design and manufacture) can have over 200 radiant tubes.
Conclusion
Currently, cast alloy tubes dominate the market. The concept of total life cycle cost has been introduced as a means of more accurately justifying one’s choice of radiant tube. This comes into play more as processes are pushed beyond traditional process conditions. Cost-benefit analysis must be balanced over acceptable amortization time, of course. However, performing the full analysis as well as the costs saved from downtime may lead some heat treaters to some alternate materials.
About the author: Marc Glasser is the director of Metallurgical Services at Rolled Alloys and is an expert in process metallurgy, heat treatment, materials of construction, and materials science and testing. Marc received his bachelor’s degree in materials engineering from Rensselaer Polytechnic Institute and a master’s degree in material science from Polytechnic University, now known as the NYU School of Engineering. Contact Marc at mglasser@rolledalloys.com
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