Heat TreatToday publishes twelve print magazines a year and included in each is a letter from the editor, Bethany Leone. In this installment, which first appeared in the March 2025 Aerospace Heat Treatingprint edition, Bethany gives a preview of important events ahead in 2025 for the heat treating industry.
Feel free to contact Bethany at bethany@heattreattoday.com if you have a question or comment.
Just about now, the demands of one big event — welcoming a newborn into our family — will be monopolizing my time for the next few months. While I am more than happy to set aside work to get to know this little person, let’s not deny that I’m missing out on quite a few amazing industry events!
The late spring period of the year sees more people willing to travel, and so events abound for our industry. This editor’s page highlights just a few things that you can enjoy (and that I will be missing) between now and June.
March Highlights
The end of March kicks off the trade show season in Las Vegas, NV. At TMS 2025, metallurgists gather from March 23 to 27 to discuss industrial innovations. With more than 100 symposia on the docket, the sessions are divided into 11 tracks. These categories include additive manufacturing, advanced characterization methods, and light metals. The exhibition includes a poster presentation space. Suffice it to say, this event is intended for heat treat researchers and implementers who are looking to hear about practical innovations in the materials space.
April Highlights
Four years ago, I attended the International Conference on Hot Isostatic Pressing (HIP) in Ohio. This April 6 to 10, the city of Aachen, Germany, will be hosting the conference. Attend sessions and tour plants in the area over the course of several days. Additive manufacturing coupled with HIP as well as heat treating with HIP vessels will be part of the discussion. The event page says, “Improvements in HIP technology … have the potential to strengthen the competitiveness of many companies which are active in emerging industrial areas.”
During that same week, heat treaters will be gathering in Detroit, MI, for RAPID + TCT from April 8 to 10. For those interested in staying at the top of industrial innovation in additive manufacturing and industrial 3D printing, this is the event to watch. Browse real-world solutions at the show and dig into the details at technical sessions. Being that this is the largest AM show in North America, it is worth a visit if this is a technology your operations are curious about or interested in understanding better.
The following week, CastExpo will be attracting suppliers, peers, and customers to the casting market. Happening in Atlanta, GA, from April 12 to 15, this is primarily a time once every three years to network and advance strategy. Among the different topics addressed through exhibits, presentations, and featured events, two are particularly noteworthy for the U.S. manufacturing industry in 2025: reshoring and supply chain & logistics. Of ever-growing importance are topics such as artificial intelligence & machine learning and simulation.
If you are interested in any part of the ceramics supply chain — be it sourcing material or implementing new technologies, the Ceramics Expo USA in Novi, MI, will be the event to attend from April 28 to 30. is annual event, like many, offers space to collaborate and new partners to create solutions.
May Highlights
Launch your May with AISTech 2025 returning to Nashville, TN. The annual iron and steel conference offers opportunities to connect and hear advances happening in the industry. There are so many opportunities to connect with suppliers in the industry and advance one’s understanding of what is happening. From May 5 to 8, you can take the pulse of what direction this segment of American manufacturing is headed and how to prepare.
Bonus Event
While nominations are always open, Heat TreatToday’s40 Under 40 launch will be happening in May 2025. Jayna McGowan led the charge last year, and the team already is excited to see what in-house heat treat professionals in North American manufacturing will be nominated and recognized this year. Visit www.heattreattoday.com/40under40 for more information about how to nominate.
I’m looking forward to reconnecting with the industry folks later this summer. In the meantime, there are a few Heat Treat Kids onesies I’m needing to sort …
A major automaker announced a $20 billion investment in United States-based manufacturing.
Hyundai‘s investment, which the automaker described as a pledge to increase localized production in the United States, will create over 1,000 jobs. As part of the pledge, the company will open a $5.8 billion steel plant in Louisiana.
This near-shoring move by Hyundai is one among many automakers who are currently planning major U.S. investments, including Stellantis, which promised $5 billion to U.S manufacturing and Honda, which is expected to produce new Civic hybrids in Indiana.
Press release is available in its original from here.
A shipment of six (6) heavy-duty walk-in batch ovens was delivered to a manufacturer of products for the energy industry. These industrial ovens will be used for baking glue onto products.
Mark Schahczinski, Senior Sales Engineer, Wisconsin Oven Corporation
The batch ovens, from Wisconsin Oven Corporation, have a maximum operating temperature of 500°F and guaranteed temperature uniformity of ±5°F at 285°F. A combination airflow configuration ensures even heat distribution throughout the chambers to optimize heating rates and temperature uniformity. Nine (9) point profile tests were conducted in each empty chamber under static operating conditions to verify temperature uniformity.
“We are proud to continue our partnership with this valued customer who has purchased multiple ovens from Wisconsin Oven over the years. Their trust in our products is a testament to our commitment to providing high quality equipment and building long term relationships with our customers,” said Mark Schahczinski, Senior Sales Engineer, Wisconsin Oven Corporation.
Press release is available in its original form here.
In today’s News from Abroad installment, we highlight processing and initiatives that aim to improve operations and improve sustainability. Read more about a method used in the production of parts with complex geometries; a venture to create the world’s first fossil-free, ore-based steel with renewable electricity and green hydrogen; and a production plant that will generate around 9,000 tons of green hydrogen a year to be used for the production of carbon-reduced steel.
Heat TreatTodaypartners with two international publications to deliver the latest news, tech tips, and cutting-edge articles that will serve our audience – manufacturers with in-house heat treat. Furnaces International, a Quartz Business Media publication, primarily serves the English-speaking globe, and heat-processing, a Vulkan-Verlag GmbH publication, serves mostly the European and Asian heat treat markets.
Investing In the Future
A commitment to technical excellence and innovation in metalworking
“To meet the growing demand for qualified experts and to impart knowledge in a practical and timely manner, the OTTO JUNKER Academy has been offering a comprehensive professional training program for the planning, modernization, operation, repair and maintenance of industrial furnaces since 2014. The program covers key areas such as induction melting and heat treatment of metals, as well as universal topics such as economy and energy efficiency. In addition to the technical content, participants are also introduced to theoretical peripheral subjects directly related to industry and development. Safety aspects at all levels are also given priority.”
READ MORE:“OTTO JUNKER Academy: Practical professional training for the future of the metal industry for more than ten years” at heat-processing.com
EAF Replaces Blast Furnace at SSAB’s Site in Sweden
Swedish steelmaker SSAB blast furnaces in Oxelösund, Sweden, replaced with an electric arc furnace.
“Swedish steelmaker SSAB is replacing its blast furnaces in Oxelösund, Sweden, with an electric arc furnace and associated raw material handling. The aim is for the new production system to be up and running towards the end of 2026. The Oxelösund mill is the first in the green transition of SSAB’s entire Nordic production system….
SSAB has obtained all the required permits and secured the availability of sufficient amounts of fossil-free electricity.”
State-of-the-art Condoor® systems for electric arc furnace (EAF)
“SMS group has been awarded a contract by Celsa Barcelona to supply two state-of-the-art Condoor® systems for electric arc furnace (EAF) #2, along with relevant modifications to the electrics and automation. This collaboration marks another milestone in the long-standing partnership between the two companies, aimed at enhancing operational efficiency and sustainability in steel production.
The Condoor® technology is set to improve the performance of electric arc furnace #2 by increasing the yield and improving safety with manless operation on the floor. These enhancements are expected to provide Celsa Barcelona with OPEX savings and operational efficiencies, aligning with their commitment to sustainable steelmaking practices. The delivery of the Condoor® system is planned for November 2025.”
A screws and fasteners manufacturer for the aviation industry is expanding its heat treating operations with a vacuum furnace with high-pressure gas quenching (HPGQ) and high vacuum for multipurpose and dedicated applications. The vacuum’s heating chamber is 16x16x24 in (400x400x600 mm), a compact design that accommodates the company’s small in-house hardening plant while still being large enough to enable efficient heat treatment of multiple components at once.
Maciej Korecki Vice President of Vacuum Business Segment SECO/WARWICK
The SECO/WARWICK furnace is designed with the ability to work on both nitrogen and argon and includes a round heating chamber with a temperature uniformity of +/-9oF (+/-5oC), and convection heating up to 1590°F (850°C). The Vector HV (high vacuum) furnace meets standards required in the heat treatment of components intended for the aviation industry; material heating processes require cleanliness (which is why an additional argon-partial pressure system was used) and a high heating temperature of 2192oF (1200oC).
“The Client required very short cooling times, which are possible with the use of a 15 bar abs gas blower,” said Maciej Korecki, vice president of the vacuum segment, SECO/WARWICK Group. “Our advantage is that it is a proven solution (our standard but adapted to the partner’s specific requirements). Vector offers wide personalization possibilities, which significantly reduces project costs and ensures faster implementation time.”
Press release is available in its original from here.
Part 1 of this article by Dave Deiwert, owner and president of Tracer Gas Technologies, was published inHeat Treat Today’sNovember 2024 Vacuum Heat Treatprint edition and online and explored finding leaks with and without a leak detector, the best equipment for leak detection, and 10 tips for finding a leak with a helium leak detector. In this week’s Technical Tuesday we bring you part 2, where Dave further addresses leak detection using a helium leak detector including modern advancements in helium leak detector technology, the best place to connect a leak detector, maintaining a leak detector, and discerning whether to repair or replace components with a leak.
This informative piece can be found in Heat Treat Today’sMarch 2025 Aerospace print edition.
Past Challenges in Leak Detector Operation
When I started my career in 1989, helium leak detectors required frequent maintenance, often caused by improper shutdown or power outage. Another problem with the older detectors is how easily someone can improperly disconnect the test line while it is still in test mode. These situations could cause backflow of diffusion pump oil. An improper shutdown or power loss often required a major overhaul of the leak detector before you could use it again.
If an operator or maintenance technician forgot the leak detector was still in test mode and disconnected the test line from the leak detector to the furnace, the inrush of air to the leak detector also would require a major overhaul of the leak detector. Sometimes the inrush of air would cause the filament in the mass spectrometer to burn out. Additionally, in the days of diffusion pump leak detectors, significant backflow of diffusion pump oil could enter the valve block and possibly the mass spectrometer.
Modern Advancements in Helium Leak Detectors
The first major improvement in leak detector design targeting reliability and significantly lowering the cost of ownership was replacing the diffusion pump in the detector with a turbo pump. Replacing the diffusion pump with a turbo pump in modern leak detectors allows that leak detector to get into test mode sooner at a higher crossover pressure.
Figure 1. Evaluating a vacuum furnace for leaks
In addition, the turbo pumped leak detectors are much less at risk for pressure bursts due to opening the test line while still in test mode or operating some process gas valve while the leak detector is in test mode. With diffusion pumped leak detectors, these events cause a significant maintenance event. But with a turbo pumped leak detector, most likely it will drop out of test mode but be ready to go back into it once the pressure burst event has been solved.
A third benefit of the turbo pumped leak detectors is they typically have a much better helium pumping speed during testing which helps with response time, reaching base leak rate sooner, and recovering more quickly after detecting a leak.
Lastly, leak detectors with greater helium pumping speed benefit with a greater signal-to-noise ratio.
The next major advancement in leak detector design was replacing tungsten filaments with thoria-coated iridium; today the whole leak detector industry is using yttria-coated iridium filaments. The newer fi lament materials operate at a lower temperature but the most significant benefit is how much more robust they are to pressure bursts. Tungsten filaments used in older leak detector mass spectrometer designs would “burn out,” creating an open circuit and loss of operational capability of the leak detector. My experience and that of others shows you can expect to get thousands of hours of more use from each modern filament vs. the old tungsten filaments. This development further aided the reliability and cost-effective ownership of leak detectors.
Another advancement is that modern detectors can now respond to sudden rises in test pressure. If an operator accidentally leaves the leak detector in test mode and then proceeds to disconnect the hose from the furnace, the leak detector will likely sense the sudden rise in test pressure, close the test valve, and then turn off the mass spectrometer filaments and amplifier to protect them and the turbo pump from the pressure spike. The leak detector will document the event as an alarm but soon be ready for the next test with no maintenance required.
Older technology leak detectors gave the user no status signals beyond:
Filament on or off
High vacuum for mass spectrometer gauge or status light
Sight glass for the rotary vane pump
Most likely an end user with an older leak detector has to rely on the manufacturer or other third-party service company to repair or provide preventative maintenance.
Newer technology leak detectors have a full range of alarms and status messages for any issues of concern. For example:
Filament on or off
Filament life or condition
Test port pressure
High vacuum gauge
Turbo pump controller status readings
Error messages for any problems detected
Next maintenance date required
Last calibration performed
Many other messages per the manufacturer’s manual
Figure 2. Dave with a vacuum pumping system recently remanufactured by Midwest Vacuum Pumps Inc. in Terre Haute, Indiana
Maintaining an Older vs. Modern Leak Detector
An end user or OEM still using diffusion pumped leak detectors with tungsten filaments is probably overhauling their leak detector every one to two years at best, or multiple times per year at worst. Depending on how much they use it and how knowledgeable their operators are, the obsolete leak detectors are probably costing them at least several thousands of dollars per event, not to mention the time lost in production as they wait to get a leak detector working so they can find the leak in their furnace.
On the other hand, an end user or OEM with a modern helium leak detector may be fortunate enough to have their model still in production by their supplier today. They can most likely go several to many years without maintenance beyond maintaining the oil quality and level in the rotary vane pump of the leak detector.
Where To Connect the Leak Detector
Figure 3. Leak testing a vacuum furnace
Th ere has been much discussion over the years on where to connect the leak detector to a vacuum furnace. Some think that because they are leak testing a furnace they should connect the leak detector directly to the furnace. While you can do that, you are asking a leak detector — typically with an NW25 vacuum connection or some type of hose barb connector — to compete with the typically very large port of the diffusion pump; in systems without a diffusion pump, the leak detector competes with the blower. In molecular flow level of vacuum, the conductance of helium to that 1” target is significantly lower than the conductance to the port of the valve to the diffusion pump or the blower (imagine a 1” vs. a 10” connection, for example).
It is best to connect to a port near the inlet of the blower, which is typically available. You would still be using an NW25 vacuum connection or smaller hose barb fitting, but you will be sampling the flow to the blower. The recommended connections from the leak detection to the blower should all be the same as to the leak detector test port. Using smaller connectors to the leak detector diminishes conductance to the leak detector from the furnace. This, in turn, decreases the performance of the leak detector.
It is also best to have a manually operated NW25 ball valve that is permanently installed at this point, which would be closed normally with a “blank” fitting clamped to the port on that valve. This would facilitate the following recommendation that preventative maintenance leak checks be completed during long furnace processes.
How To Conduct Preventative Maintenance Leak Checks During Operation
While the furnace is under vacuum in a long furnace process, place the leak detector in test mode. While in test mode, the leak detector creates a vacuum to the closed ball valve on the furnace, as previously recommended. Next, place the leak detector momentarily in standby mode. This closes the test valve of the leak detector but does not vent the test port. Then, open the ball valve. This lets the leak detector test port gauge show the current vacuum level now that it’s connected to the furnace. Now put the leak detector back into test mode.
At this point, you are ready to spray helium at potential leak points on the furnace. While many often begin checking with the leak detector hose at the ball valve to ensure they did not create a leak during assembly, then it is best to move to the opposite side of the furnace — to the furthest point of the vacuum system of the furnace — and slowly work back to the pumps.
A common question is how much helium should you spray? People often say they were taught to adjust the helium spray so that they get one or two bubbles in a glass of water per second or to adjust the spray so that they can barely feel it on their lips or tongue. That last one makes some people nervous. Then, it is basically like playing the hot and cold game as you spray the potentially leaking points of the furnace. More information on helium spray technique can be found in part 1 of this article.
Finding a Leak
The closer you get to a leak, the larger and faster the response will be on the leak rate meter of the leak detector. To confirm that you have located a leak, repeatedly spray the point of leakage and ensure that you get the same peak leak rate display and response time with each spray at that leak point.
Earlier we mentioned that you can accomplish preventative maintenance leak checks on furnaces while in a long process. This is because helium is inert, as mentioned in part 1 of this article. Many times, operators have told me they know of a persistent leak and have not been able to repair it; as the leak is so small, they say it does not affect their product quality. Therefore, it is possible for any furnace operator to: (a) do a preventative maintenance leak check and discover a leak they did not know they had, and then (b) have the option of marking or tagging that leak to do a preemptive repair at their convenience, as opposed to discovering it aft er it degrades to the point of causing a production shut down.
Figure 4. Dave in the front of a vacuum furnace at Mercer Technologies, Inc., in Terre Haute, Indiana
To Repair or Replace?
If you find a leak in a component like a valve, fitting, or thermocouple, you must then consider if the component is something that can be repaired or needs to be replaced. Often components that can be repaired may have a repair kit available from the manufacturer. If you have a leaking door seal, for example, you may be able to clean and, if appropriate, relubricate the seal. If it is damaged or worn, then replacement would be necessary.
The only temporary repairs that come to mind are, for example, a cracked weld or substituting a failed pump with a lower performing pump. For the cracked weld, you may discover that applying some vacuum-appropriate putty or similar material may help the furnace back to approvable vacuum capability. However, a repair like this should only be considered a temporary solution with plans to repair the weld at the earliest opportunity.
For a failed pump, you may replace it with another pump that might not have the same performance but is capable of the same vacuum level. While your process time might be slower, at least you can continue producing product until appropriate repairs can be made to the failed pump or you can replace it with the same type of pump.
Importance of Leak Detection
A leak on a vacuum system introduces air, thereby affecting the quality of the product or even ability to reach the process vacuum level. To ensure the quality of heat treated parts and prevent long delays in production, it is critical that heat treat operations with vacuum furnaces are well-versed in their equipment and leak detection resources, whether they own and operate helium leak detectors or hire a manufacturer or a third-party service company to detect and repair leaks.
About The Author:
Dave Deiwert President Tracer Gas Technologies
Dave Deiwert has over 35 years of technical experience in industrial leak detection gained from his time at Vacuum Instruments Corp., Agilent Vacuum Technologies (Varian Vacuum), Edwards Vacuum, and Pfeiffer Vacuum. He leverages this experience by providing leak detection and vacuum technology training and consulting services as the owner and president of Tracer Gas Technologies. Dave is a Heat Treat Consultant. Click here for more about Dave and other consultantsHeat Treat Today consultants.
Heat TreatToday publishes twelve print magazines a year and included in each is a letter from the publisher, Doug Glenn. This letter first appeared in March 2025 Aerospace Heat Treatingprint edition.
The world is a better place when people know what their job is and then stick to that job. When the carpenter knows that their job is working with wood and then works with wood, things go well. When the pipefitter doesn’t try to be an electrician but sticks to pipefitting, things go well. It’s only when we forget (or never knew) who we are or why we’re here that things begin to go terribly wrong.
This is just as true in the C-suite as it is on the shop floor when it comes to running a business. CEO, CFO, COO, presidents, and VPs all benefit the business by sticking to their huckleberry bush just as the welder, the electrician, and the plant operations guys prosper the business when they do what they’re called to do.
In the C-suites, however, there seems to be more confusion about what it is they are there to do and company leaders more frequently get distracted from their huckleberry bush than do the guys in the shop. Here are some good, yet ultimately unhelpful things that have kept company leadership from focusing on profits — which ought to be their huckleberry bush.
Environmental Concerns
If ever there was a worthy cause, caring for the planet should be toward the top of the list, coming in second only behind caring for people. Business leaders proceed at their own risk if they completely ignore environmental issues. But elevating “saving the planet” over profits is a common mistake made by well-meaning leaders. The driving question that should underlie all business questions is whether or not profits will increase, not only what impact the decision will have on the environment. The EV craze, which has petered out significantly since this time last year, is a great example of company leaders losing sight of profits in favor of the environment. The number of car manufacturers who boldly announced electric-only or significantly enhanced EV fleets in 2024 only to have the two-by-four of company profits hit them squarely upside the head is astounding. Most of them have backtracked or are in financial hardship for not backtracking.
Well-meaning environmentalism should never come at the expense of profits.
Diversity, Equity, Inclusion (DEI)
Another distraction from focusing on profits has been, while to a lesser degree now as compared to this time last year, the DEI movement. DEI, to its credit, is people-focused and, undoubtedly, was well-motivated by many. Nonetheless, kowtowing to externally imposed social norms in order to avoid becoming a corporate pariah carries with it the seeds of failure, because profits and overall corporate health will suffer. Such was the case for countless large and small companies, including McDonalds and Harley Davidson, that elevated DEI above profits. The primary (though not the only) factor that should drive hiring and promotional concerns within a company should be competency and effectiveness. Will the individual help enhance company profits or not?
“Profit” Is NOT a Four-Letter Word
In her classic work, Atlas Shrugged, Ayn Rand makes this very point. When we vilify “profits,” we do not do ourselves or our fellow man any good. One might say, “It is not profitable to vilify the word ‘profit.’” Profit is good, and it is enormously comforting to see company leaders of all stripes returning to a good, healthy embrace of the profit motive.
Obviously, the ill-founded desire for profits at all costs regardless of the impact on the freedoms and liberties of others is not good and is the exact reason why we have courts of law. Profit cannot and ought not be at the expense of others’ freedoms. Further, the profit motive should not go right up to the line of violating personal freedoms. A true and good profit motive is not devoid of compassion and long-term thinking. It values human life and liberty and tempers its decisions based on what is good in the long run for human flourishing. Sound, profit-motivated decisions are often not easy black and white decisions. There are countless intricacies and complexities. Nonetheless, our default position ought not to be the disparaging of profits. Quite the opposite.
Company leader, stand strong as you do all that you can to build your company profits and don’t be ashamed to say so.
thyssenkrupp Steel, a supplier of high-grade flat steel, recently upgraded with the modernization of a walking beam furnace installed at the company’s hot strip mill. The plant enhancement will improve production capability, increase quality of the electrical steel strip, and reduce specific consumption.
The modernized furnace is provided by Tenova Italimpianti, a Tenova division with technologies for reheating, heat treatment, strip processing, acid regeneration plants, and cold rolling mills. thyssenkrupp Steel‘s new overhauled system includes an improved refractory lining design and an optimized fixed and walking beam system, which lead to a more uniform temperature distribution along the entire slab length. This reduces temperature loss in the slab’s center and minimizes contact points (rails) between the slabs and the fixed and walking beam system, preventing surface defects.
“The modernization of this walking beam furnace supports our goals for efficiency and sustainability. Tenova has played a key role in this process,” said Viktor Schlecht, head of Hot Strip Mill 1, at thyssenkrupp Steel in Duisburg Bruckhausen, Germany. “We had already successfully collaborated on a new walking beam furnace at our Beeckerwerth Hot Strip Mill 2 in Duisburg, where Tenova’s contribution was crucial in helping us potentially reduce CO2 emissions by more than 20% through the use of hydrogen.”
“We are proud to have partnered with thyssenkrupp Steel for this project, which supports their forward-looking strategy,” said Alessandro Sicher, project engineer coordinator for Reheating Technologies at Tenova. “Our equipment ensures the maximum production of high-quality electrical steel strips while enhancing the sustainability of the heat treatment process.”
The upgrade includes new state-of-the-art UltraLowNOx burners for coke oven gas fuel application. The customized design, enhanced with a modern control system, ensures optimal heating distribution in the furnace with significantly reduced nitrogen oxide (NOx) emissions. Additionally, a new automatic descaling concept was incorporated, reducing the cleaning intervals and optimizing heat treatment processes. The safety systems were upgraded to meet the latest standards for industrial furnaces.
Main image caption: thyssenkrupp Steel Bruckhausen plant, Duisburg, Germany
Press release is available in its original form here.
One of North America’s leading producers of ultra-high-purity alumina and associated products recently boosted its advanced manufacturing operations with a 50m-long electric tunnel kiln. This installation will support the company’s expansion into the production of a variety of high specification lines.
Alberto Cantú Br<> Vice President of Sales NUTEC Bickley
The calcination kiln, which was broken down into modules and transported by NUTEC Bickley, has an operating temperature of 2190°F (1200°C) and maximum temperature of 2460°F (1350°C) and processes the material in saggars sitting in six-high stacks that are loaded on to 33 cars. With afiring cycle of 23.6 hours, approximately 5000kg of calcined material is processed each day. In addition, special provisions to prevent equipment wear due to chemical attack that follows degassing of hydrochloric acid during the alumina heating process has been designed by NUTEC Bickley.
“The nature of the material being processed means that tight tolerances and demanding specifications have had to be met,” said Alberto Cantú, vice-president of ceramics at NUTEC Bickley. “[This] demonstrates once again how, when all necessary design parameters are in place, electric heating in continuous kilns can deliver for a wide range of manufacturing processes.”
The use of electric heating is increasingly in demand. Extremely tight thermal control is necessary in the kiln chamber, operating under an oxidizing atmosphere, and this particular kiln has 14 automatic control zones for heating, plus two automatic zones for cooling. To ensure maximum flexibility and management of the temperature profile, the control systems are arranged so that the exhaust, heating zones, and cooling zones are all independently regulated.
Image 1. 3D view of the electric tunnel kiln, showing its structural design and distribution of key components. Image 2. External view of the electric tunnel kiln installed in the plant.
The heating system comprises a combination of silicon carbide and metal alloy elements. These hang down vertically through the roof and are sited on either side of the load, with distribution configured to deliver a well-balanced temperature uniformity throughout the kiln. The electrical connection design means that elements can be replaced while the furnace is at operating temperature.
Hot gases are drawn towards the kiln entrance and are evacuated from the tunnel through exhaust ports positioned in the kiln sidewalls, via the exhaust fan. Cooling is achieved by direct air movement in the cooling zones. The temperature set points from the cooling zones are controlled automatically with cooling nozzles positioned to blow a stream of cold air above and below the load setting. The kiln walls use lightweight insulation for rapid thermal response and fuel economy, with the lining rated for use up to 2350ºF (1290°C). The roof is lined with high thermal efficiency ceramic fiber system, and the roof insulation combines modules of polycrystalline fiber and zirconia grade fiber.
Kiln car operation is based on a semi-continuous feed electromechanical pusher with push speed adjustment. The push speed is configurable by selecting the appropriate firing schedule at the kiln control panel. A vestibule arrangement serves to reduce exchange of air and gases between the factory and the kiln. When a car is being introduced into the kiln, the door at the entry end opens, while the door at the kiln entrance is closed.
The vestibule has two sections: the first accommodates a single car and is separated by two vertical lift doors to separate the factory’s atmosphere from the kiln atmosphere. This is managed by installing an exhaust hood which is connected to the entry exhaust fan, thus ensuring a negative pressure in the vestibule to avoid any gases from the kiln from leaving the chamber. The second section functions as a transition from the vestibule door sections to the kiln’s pusher.
Press release is available in its original form here.
In each installment of Combustion Corner, Jim Roberts, president of U.S. Ignition, reinforces the goal of the series: providing informative content to “furnace guys” about the world of combustion. The previous column examined the air supply inlet — the inhale, and this month, Jim is examining the exhaust system — the exhale, and how to inspect it, maintain it, and manage it.
This informative piece was first released in Heat Treat Today’sMarch 2025 Aerospace print edition.
A guy walks into a room full of furnace guys and says, “Is it just me, or is it a tad stuffy in here?”
We have all been able to imagine that it is hard to focus and do your job in an environment where it seems like it’s hard to breathe. Well, our hard workin’ buddy, the furnace, is continually stuck in a cycle of trying to breathe in, breathe out — and then somewhere in between, the magic of combustion and heat happens! We talked last month about the “breathe in” part of the combustion process. This month, we are going to remind you that if you take a really good, productive, inhaled, life giving breath, you are probably going to want to exhale at some point, too!
Tip 2: Ensure Exhaust Systems Are Properly Functioning and Clean
Inhale, exhale. It makes sense that if we were earlier having issues with the air supply inlet, the exhaust should also be checked. Today’s combustion equipment is sophisticated and sensitive to pressure fluctuations. If the exhaust is restricted, the burners will struggle to get the proper input to the process. I used to use the example of trying to spit into a soda bottle. Try it. It’s tough to do and invariably will not leave you happy. Clean exhaust also minimizes any chance of fire. Read on for three examples.
A. Check the Flues and Exhausts for Soot
If you are responsible for burners that are delivering indirect heat (in other words, radiant tubes), you have a relatively easy task ahead to check the flues/exhausts. Each burner usually has its own exhaust, and one can see if the burners are running with fuel-rich condition (soot/carbon). Soot is not a sign of properly running burners and will signal trouble ahead. Soot can degrade the alloys at a chemical level. Soot can catch fire and create a hot spot in the tubes. Soot obviously signals you are using more fuel than needed (or your combustion blower is blocked, see the first column in this series).
As a furnace operator or floor person, it should be normal operating procedure to look for leakage around door seals.
Here’s a sub tip: If you cannot see the exhaust outlets directly, look around the floor and on the roof of the furnace up by the exhaust outlets. Light chunks of black stuff is what is being ejected into the room when it breaks free from the burner guts (if it can). That will tell you it’s time to tune those burners. If you do not have a good oxygen/flue gas analyzer, get one. It can be pricey, but it will pay for itself in a matter of months in both maintenance and fuel savings.
B. Seriously … Check the Flues and Leakage Around Door Seals
If you are running direct-fired furnace equipment, or furnaces that have the flue gases mixed from multiple burners, it gets a little trickier. All the same rules apply for not wanting soot. Only now, it can actually get exposure to your product, it can saturate your refractory, and it can clog a flue to the point that furnace pressure is affected. An increase in furnace pressure can test the integrity of your door seals. It can back up into the burners and put undue and untimely wear and tear on burner nozzles, ignitors, flame safety equipment, etc. As a furnace operator or floor person, it should be normal operating procedure to look for leakage around door seals.
C. Utilize Combustion Service Companies
Ask the wizards. Combustion service companies can usually help you diagnose and verify flue issues if you suspect they exist. It’s always a great idea to set a baseline for your combustion settings. Service companies can help you establish the optimum running conditions. Again, money well spent to optimize the performance of your furnaces. I’m sure you already have a combustion service team; some are listed in this publication. Otherwise, consult the trade groups like MTI and IHEA for recommended suppliers of that valuable service.
Check flues monthly. It should be a regular walk around maintenance check.
Don’t let the next headline be your plant. See you next issue.
About The Author:
Jim Roberts President US Ignition
Jim Roberts, president at US Ignition, began his 45-year career in the burner and heat recovery industry directed for heat treating specifically in 1979. He worked for and helped start up WB Combustion in Hales Corners, Wisconsin. In 1985 he joined Eclipse Engineering in Rockford, IL, specializing in heat treating-related combustion equipment/burners. Inducted into the American Gas Association’s Hall of Flame for service in training gas company field managers, Jim is a former president of MTI and has contributed to countless seminars on fuel reduction and combustion-related practices.
