Heat Treat Today’s contributing experts series on emerging technologies examines how modern automation and manufacturing tools are reshaping heat treat operations. In this Emerging Technologies installment, Alex Marcy, CEO of Corso Systems, discusses why programmable logic controllers (PLCs) and human machine interfaces (HMIs) must be current, sercure, and performing as designed before heat treaters add layers like analytics, data collection, or advanced integration. Marcy outlines what that readiness looks like, from updated firmware and cybersecurity alignment to reliable long-term operation, and explains how the benefits include reduced downtime risk, greater repeatability, and better data quality.
This informative piece was first released in Heat Treat Today’sSeptember 2026 People of Heat Treat print edition.
Editor’s Note: Alex Marcy’s contributing columns to this series will cover his ten steps of progressive heat treat automation adoption. This column is just step one but yields fully actualized benefits even if you stop here. Look out for his future installments.
Programmable Logic Controllers (PLCs) and Human Machine Interfaces (HMIs) are the foundation of every automation system. PLCs run your equipment using logic to perform repeatable operations and HMIs give your staff control over and display the status of your equipment and production lines. Outdated, unsupported, or misconfigured PLCs and HMIs limit visibility, increase risk, and create roadblocks for future growth.
Ensuring these core systems are up to date is critical before adding technology layers like analytics, data collection, or advanced control and integration.
The first step towards a fully integrated manufacturing process focuses on validating that your control systems are current, secure, and performing as designed. This includes:
Ensuring up-to-date and functional process control logic for automated equipment
Updating firmware and software to supported versions
Aligning your system with current cybersecurity best practices
Verifying proper configuration and operation of your equipment, PLCs, and HMIs
Ensuring reliability and maintainability for long-term, repeatable operation of your system
Benefits of using PLCs and HMIs for heat treat operations include:
Reduced risk of downtime or system failure
Increased repeatability across production runs
Improved data quality and visibility
Taking the time to address PLC and HMI readiness now prevents costly delays later. If you are using relay logic or manual controls to operate your equipment, upgrading to a PLC and HMI is a great first step. Outdated PLC equipment puts you at risk of downtime if the hardware fails and should be considered for replacement every 10 years.
Using PLCs and HMIs to run your equipment sets you up for larger benefits gained from using manufacturing technology across your business.
About the Author
Alex Marcy CEO Corso Systems
Alex Marcy is the CEO of Corso Systems, helping heat treat companies improve operations since 2011.
Industrial gas costs involve far more than the gas itself. In this Technical Tuesday installment, Dave Wolff, an independent expert focusing on industrial atmospheres for heat treat applications, draws on an interview with Josh Weinmann, president of DeLille Oxygen Co., to explore how delivery logistics, storage, tank sizing, supply contracts, and supplier selection can affect both costs and supply reliability.
This informative piece was first released inHeat Treat Today’sOctober 2026 Ferrous & Nonferrous Heat Treatments/Mill Processing print edition.
DeLille Oxygen is a regional multilocation industrial gas manufacturer and distributor serving Ohio and adjoining areas with industrial and specialty gases. The company recently celebrated its 100th year in operation, an enviable record of success. Josh Weinmann has worn many hats at DeLille, from cylinder filler and bulk driver to operations management and now is president of the organization. We discussed the importance and cost implications of gases logistics in serving industrial gases clients.
The Real Cost of Gas Delivery
Josh Weinmann President DeLille Oxygen Co.
Because industrial gases are gaseous products, shipped either as highly compressed gases or as liquefied cryogenic liquids, they are hazardous materials requiring special handling. For that reason, when a client plans to purchase bulk industrial gases from a supplier, that arrangement includes delivery of those gases to the client. While some gases may be manufactured at the client’s location (so-called on-site gas production), in most cases, the gas is manufactured at large process plants far from the client and shipped by truck to the client. The embedded shipping costs are a large fraction of the pricing that clients pay for delivered industrial gases.
Industrial gas transportation requires special trailers, drivers with specialized training and licenses, and very precise procedures. The cryogenic trailer itself may cost several hundred thousand dollars. Backhauls are uncommon, so the trailers are returned empty to the plants, further increasing costs. In Josh’s experience, delivery costs are often higher than the “spigot” price of the gas at the plant before delivery. But the gases must be delivered to be used, so clients pay for both product and delivery.
Different suppliers handle shipping costs differently. Some suppliers provide a single price for their gases, including delivery. In that case, the client may be asked to pay say 90 cents per 100 scf for their nitrogen, including delivery costs, assuming normal delivery arrangements.
Other suppliers, like DeLille, quote gas prices at the spigot (source location), plus a delivery charge. They might quote 45 cents per 100 scf at the spigot, plus a fixed freight charge per delivery, for example. The two line items, gas plus delivery, will appear separately on each invoice, providing an additional degree of transparency. This approach is clearer about the cost structure and provides the client with visibility over costs and incentive to reduce the number of delivery events by maximizing the amount delivered at each delivery event.
Understanding Your Industrial Gas Contract
Industrial gas contracts detail the financial, legal, and procedural requirements of the supplier and the client. Most bulk supply contracts span 3 to 7 years. These contracts include provisions for cost recovery by the suppliers as their costs change over time. Typically, contracts include cost recovery on electricity and/or natural gas for production of the gas product and cost recovery for changes in cost of diesel fuels and labor for delivery. There also may be factors built in for changes in overall costs such as inflation recovery. All modern contracts will also include provisions for uncommon/impactful events, such as those experienced during Covid when supply and delivery mechanisms were dramatically challenged.
Most industrial gas contracts are negotiated with a certain amount of monthly use in mind. It is important to be realistic and relatively transparent when negotiating quantities because the final contract will specify the range of product deliveries that the supplier is committed to supply and the client is required to buy. While the client may wish to get a cheaper price by specifying a larger amount of monthly use to get a cheaper price, if the client regularly uses less gas than committed to, the supplier may adjust the pricing accordingly. Possibly even more important, the contract will specify a certain increment of additional product that the supplier commits to making available to a client above and beyond their expected monthly use. You don’t want to be in the position of begging for additional gas supply to meet your needs if your business is highly successful. Commitments between clients and suppliers for industrial gases apply in both directions.
Telemonitoring and Delivery Schedule
In the past, industrial gas clients would have an employee who was responsible for monitoring the tank levels of their industrial gases and calling their supplier(s) to schedule deliveries when levels got low. That operational model has been largely abandoned, and most clients and suppliers today use telemonitoring to monitor tank levels for each cryogenic and compressed gas product in use. For cryogenic liquid tanks, telemonitoring generally monitors liquid level or uses a load cell to measure tank filled weight; for gaseous products such as compressed hydrogen, telemonitoring measures and reports on tank pressure, which corresponds to inventory. The suppliers continuously monitor tank levels and can schedule deliveries to achieve continuous supply at the lowest cost of deliveries. In theory, telemonitoring should eliminate the risk of runouts. Because telemonitoring data provides real-time data and powerful analytics regarding client gas use, DeLille makes that data available to their clients through a client portal. It is worthwhile for clients to request access to their data from tank telemonitoring.
Image Credit: DeLille Oxygen Co.
Industrial gas providers work 24×7 to produce and deliver industrial gases. DeLille, like many industrial gas providers, prefers to deliver to clients at night, when client operations are at low ebb, and traffic delays affecting expensive delivery assets are less likely. The standard contract assumes that the supplier will be able to deliver around the clock. Clients that require restricted deliveries, either fewer than 24 hours/day or only certain days of the week, will most likely be required to pay additional costs for delivery. Clients should make every attempt to provide unrestricted delivery to keep their costs down.
Making Every Delivery Count
Because liquid and gas bulk trailers are filled to capacity before they start the day, they may end the day with some residual gas that has not been delivered to clients. It is to the supplier’s benefit to deliver that remaining cargo to one of their clients before returning to refill, because it does not make sense to pay to transport the gas back and then haul it out again. As such, suppliers sometimes dump the remaining product, often just a few thousand cubic feet of gas, at a client willing to accept it.
Clients should be aware of two things regarding these unscheduled deliveries. First, every delivery requires a certain amount of gas to be wasted to depressurize tanks, fill pipes, and cool down hoses. The wasted product amount is the same regardless of small delivery or large one. The client pays for that vented product. For a large delivery, the wasted product is a small percentage, but for a small delivery of residual product, the wasted amount can be a meaningful percent of the total amount of gas to be paid for. It is fair to come to an agreement with your supplier about some equitable way for the supplier to drop off residual product without the client paying extra for gas that is wasted on a small delivery.
Because the supplier did not plan the route to fill your tank, it seems clear that the client should not pay full delivery charges for product delivered for supplier convenience. Regardless of whether your agreement splits out delivery cost or bundles it into the product price, clients should ensure they pay a full delivery fee only for product associated with a trip made specifically to meet your needs.
It is worth understanding how quantities delivered are computed for compressed and cryogenic gas deliveries. Previously, trucks with cryogenic gases would weigh before and after each delivery at a commercial truck scale, charging the client for the weight difference associated with that delivery. Now, most cryogenic trailers are equipped with calibrated volume meters, similar to the meter in a gasoline pump, that measures the exact amount of liquid cryogenic fluids dispensed. For gaseous deliveries like compressed bulk hydrogen, the delivery ticket will show the starting pressure of the receiving tank or tubes, the ending pressure, and the temperatures at the beginning and end of the delivery. The exact amount of gas dispensed can thus be determined for billing purposes.
Storage Tanks: Renting, Maintaining, and Sizing
Gas storage tanks and tubes are normally rented from your industrial gas supplier. That system works well for both supplier and client, but it does create limitations in flexibility. For example, no other supplier will deliver into a different supplier’s tank, unless written permission from the tank owner (not the renter) is received. If your supplier runs into delivery problems, you need to seek temporary written permission to have another supplier deliver.
Tank owners are responsible for having tanks inspected according to schedules established by OSHA and referring to codes from ASME and NFPA. Required inspections include insulation, piping, regulators, and safety relief valves. Industrial gas suppliers have staff to perform these inspections while clients may find it difficult or expensive to have these required inspections done. It is rarely attractive for clients to buy their own cryogenic and compressed gas storage equipment.
Cryogenic liquefied gas storage tanks are like giant thermos bottles and use a vacuum insulation system to keep the precious cryogenic liquefied gas from evaporating. The normal loss rate for a cryogenic tank evaporation rate during periods of non-use is under 1% of the tank volume per day of non-use. Over time, the vacuum may gradually leak down, creating a loss of insulation and the possible loss of gas to evaporation. Tank renters should be aware that tank evaporation rate may increase over time and should alert their supplier if they feel that evaporation has increased. It is the supplier’s job to maintain proper insulation.
Image Credit: DeLille Oxygen Co.
Most suppliers want to deliver to their clients once per month, unless the client’s usage rate is high enough to require more frequent delivery. It is important for both the client and the supplier for deliveries to be efficiently managed or there will be extra costs incurred which will eventually impact the client. Once-per-month delivery means sizing the volume of cryogenic liquid or gaseous storage to hold enough volume to enable the client to be delivered once per month without risk of runout. Because bigger tanks have a higher rental rate than smaller tanks, tank sizing can sometimes provoke a lively discussion between client looking to minimize rental rates and suppliers looking for additional storage. Experience has shown that sizing storage representing about 1.5 to 2 months use is generally the most efficient size.
While too small a tank forces extra deliveries and increases likelihood of runouts, too large a cryogenic tank can also be problematic because cryogenic evaporation rate increases with tank wall surface area; therefore, a larger tank will lose more gas during periods of non-use. One possible exception to the tank-sizing conventions may be for argon, which is subject to frequent swings in supply availability. It may be wise to moderately oversize argon storage to ensure continuous supply and eliminate risk of runouts. The extra tank capacity makes it possible to run through temporary supply shortfalls. Argon users who are willing to step up slightly in tank size may wish to try to negotiate a slightly lower gas price by improving their attractiveness as delivery locations (because the larger tank can improve delivery efficiency).
Choosing the Right Gas Supplier
When choosing a gas supplier, logistics are a huge component of the delivered gas cost to the client, even though logistics are only indirectly visible to the average industrial gas user. Just as Amazon stocks warehouses close to clients with many common items to achieve unprecedented short client delivery times, local gas distributors and industrial gas companies may have local depots where they have inventory of gases ready to be loaded and delivered to nearby clients. Talk to several potential suppliers about your use of gases to find a supplier that can meet your needs. If you use more than one bulk gas (say nitrogen plus hydrogen, for example), consider having just one supplier to vastly simplify dealing with your supplier. Be aware that the standard language of most bulk industrial gas contracts claims that the gas supplier has a right of first refusal to supply all the bulk industrial gases used at the location served (not just the gas listed on the accompanying rider document).
Industrial gases are a true commodity meaning nobody’s nitrogen is any “better” than any other supplier. As such, feel free to negotiate hard to achieve your economic and supply assurance goals when negotiating a contract. DeLille suggests that local distributors may be able to offer unique security of supply to clients while eliminating the need for clients to seek permission from their supplier for alternative supply during a supply shortfall or interruption of supply. Distributors may be able to pivot to an alternative supplier without the need for their clients to be involved.
It may not be obvious what industrial gas suppliers serve a particular area, so potential gas users can use a general-purpose search engine to find one, or consult with the member headquarters of one of the two major industry organizations: GAWDA (Gases and Welding Distributors Association) or IWDC (Independent Welding Distributors Cooperative). For highest satisfaction, choose a supplier that has a significant commitment to serving your geographic area and the gases you plan to use.
The delivery vehicles used for industrial gases can be as large as a tractor trailer, and they are transporting a dangerous cargo. As such, there is tremendous focus by suppliers on the safety of clients’ delivery environment. If a client cannot or will not provide a safe environment for a gas delivery, many suppliers will not deliver to the site or will have to use specialized equipment that will cost extra. Of particular interest to suppliers is the ability to pull through a client’s site because backing up bulk trailers is the most risky part of a delivery. If backing up can be avoided, the attractiveness of the supply contract will increase.
Negotiating a Contract that Works for Both Sides
When negotiating an industrial gas supply contract, most clients make operations the primary participant in the discussions, with procurement and legal as advisory. It seems wise to narrow the field of potential suppliers with the active participation of operations, and then use procurement and legal to avoid liability and issues with terms and conditions. The number of industrial gas suppliers is finite, and your process requires industrial gases, so be realistic about negotiations. Your objective should be to achieve a contract which serves the needs of both parties.
About The Author:
David (Dave) Wolff Industrial Gas Professional Wolff Engineering
David Wolff has over 45 years of project engineering, industrial gas generation and application engineering, marketing and sales experience. Dave holds a degree in engineering science from Dartmouth College. Currently, he consults in the areas of industrial gas and chemical new product development and commercial introduction, as well as market development and selling practices.
Jim Roberts of U.S. Ignition engages readers in a Combustion Corner column about the three methods of heat transfer found in heat treating shops — examining how advection, convection, and radiation each move thermal energy, from forced hot-gas circulation by fans and burners, to the natural buoyancy-driven stirring of fluids, to the electromagnetic waves emitted by glowing radiant tubes that deliver the temperature uniformity so critical to heat treating.
This informative piece was first released in Heat Treat Today’sSeptember 2026 People of Heat Treat print edition.
A furnace guy walks into a heat treat facility and says, “Hey, I think I’m warming up to this place.” The operators say, “It’s about time… and temperature.” This might be a lame joke on the most common requirement in heat treating, but time at temperature is the secret, right? How we get that combination of properties is the question.
Last month, we discussed that one of the Laws of Thermodynamics was advection. It’s not a term we use regularly, but it’s a better description of what we experience in our lives. Advection is when hot gases or hot atmosphere is circulated by force. In other words, it is not a natural transfer of heat to the product. It is when that heat is forced around the work piece, and it is in a state of unnatural agitation. We are moving the heat around by a fan or the velocity of the hot gases from the burner, some method of creating a “stirring effect” by using another energy source. A great example would be a heated fan. You can feel the heat from the coils, but most of that is because the air movement of the fan is scrubbing off the heat from the heat source and blowing it at you. Both the heat transfer of the heat source to the air and then that air transferring heat to you are examples of advection.
Now we turn to convection. Convection is sometimes described as a form of thermal transfer wherein the motion of a fluid is driven by the buoyancy of the fluid and is caused by temperature differences in the fluid. In engineering circles, a fluid can be liquid, air, a gaseous atmosphere, etc. Convection is all natural, and advection is using outside energy. A mug of hot water will lose its heat through the change in temperature caused by thermal lift in the liquid. Then, it will continue to transfer and lose heat as the steam or temp continues to rise away from the mug and into the air, all by natural stirring or lift. That mug will eventually release its thermal energy and equalize with the area around it.
This leads us to radiation. Ansys Engineering describes radiation as the mechanism that transfers heat energy as electromagnetic waves or photons. That’s right, Capt. Kirk, that phaser technology might just be real! In other words, thermal energy can cause the atoms in any matter to move. The movement of those charged particles (protons and electrons at an atomic level) will result in the release of electromagnetic radiation. In its purest form, radiation heat transfer will only occur in a vacuum or through a medium that is transparent to the radiation. Furnace atmospheres come to mind.
Also, re-radiation is possible from an object, such as a heat treating load, so the radiant source is also absorbing radiation some of the time. Radiation transfer is very efficient and is used effectively in radiant tube furnaces. The tubes are heated electrically or by gas burners, and when they begin to glow (somewhere around 1250°F), they begin in earnest to try and bring the furnace or the load up to temperature.
Image Credit: Ashikul / AdobeStock
When radiation is at work, these types of heating devices provide good temperature uniformity. This is because once the furnace has determined that the chamber temp has been achieved, the radiation will continue to try to bring the chamber up to temperature, and these electromagnetic pulses try for equilibrium in the chamber.
Radiation is very efficient in most cases. Radiation is like a living thing — it wants everything to be the same temperature. So it normally has sight line between the glowing heat source and the load. Thermal radiation transfers heat via infrared rays and visible light waves. Hot furnace walls and heating elements emit these electromagnetic waves, which then heat the metal parts without needing direct contact or air movement.
That covers the styles and methods of heat transfer we can see in our heat treating shops. We’ll pick up a new topic next month.
About The Author:
Jim Roberts President US Ignition
Jim Roberts president at U.S. Ignition, began his 45-year career in the burner and heat recovery industry focused on heat treating specifically in 1979. He worked for and helped start up WB Combustion in Hales Corners, Wisconsin. In 1985 he joined Eclipse Engineering in Rockford, IL, specializing in heat treating-related combustion equipment/burners. Inducted into the American Gas Association’s Hall of Flame for service in training gas company field managers, Jim is a former president of MTI and has contributed to countless seminars on fuel reduction and combustion-related practices.
Inductor design plays a critical role in heating efficiency, temperature uniformity, and process stability, but conventional manufacturing methods can limit what coil geometries are possible. In this Technical Tuesday installment, Max Wissing, technology manager at PROTIQ, explores how 3D-printed copper inductors expand design freedom, allowing heat treaters to more closely tailor electromagnetic fields, cooling, and overall coil performance to demanding applications.
This informative piece was first released inHeat Treat Today’sOctober 2026 Ferrous & Nonferrous Heat Treatments/Mill Processing print edition.
Why Inductor Design Matters More Than Ever
Induction heating remains one of the most established and widely used technologies in modern heat treating. It enables precise, contactless energy transfer and offers a high degree of repeatability, making it particularly suitable for demanding applications, such as surface hardening, partial hardening, and localized treatment of highly stressed components.
At the same time, requirements in industrial heat treatment continue to increase. Manufacturers are expected to improve energy efficiency, reduce cycle times, and maintain consistent process quality. These demands are further intensified by the growing complexity of component geometries, which require more precise control of electromagnetic fields and temperature distribution than ever before.
Within this context, the inductor itself becomes a decisive factor, as its design directly influences heating behavior, efficiency, and process stability. However, many conventional inductors are still constrained by the limitations of their manufacturing methods. These constraints often force compromises between manufacturability and functional performance, meaning that coil geometries are not always ideally adapted to the component or the specific heat treat application. In more complex cases, this can lead to reduced energy efficiency or non-uniform temperature distributions, ultimately affecting process consistency.
In response, recent developments have increasingly focused on application-driven coil design and improved engineering approaches. Industrial 3D printing introduces a fundamentally different paradigm by enabling inductors to be designed according to functional requirements rather than production constraints. This shift opens up new possibilities for optimizing electromagnetic field distribution, improving energy transfer, and enhancing overall process performance in induction heat treating.
Where Conventional Coil Design Reaches Its Limits
Traditional induction coils are typically manufactured by bending and assembling copper tubes or machined elements. These methods are well established and widely used, but they impose inherent restrictions that can limit further optimization.
Geometric flexibility, for example, is constrained by bending radii and available tube profiles. As a result, the coil design often represents a compromise between what is theoretically optimal and what can be manufactured. In more complex applications, this can lead to non-uniform heating or less efficient energy coupling.
In addition, conventional manufacturing involves a considerable degree of manual work, which can introduce variability. Small deviations in geometry may affect electromagnetic behavior and, consequently, process consistency. The presence of joints — created through soldering or welding — further introduces potential weak points that can impact durability under thermal and mechanical stress.
Taken together, these factors not only influence manufacturing efficiency but also define the performance limits of the entire induction heating process.
3D Printing as a Design Enabler
Industrial metal 3D printer | Image Credit: PROTIQ
Additive manufacturing, often referred to as industrial 3D printing, is a production technology that creates metal components directly from digital design data. In processes like laser powder bed fusion (LPBF, often called SLM), a high-power laser selectively melts thin layers of metal powder. By repeating this process layer by layer, complex metal parts can be produced without the need for molds, tooling, or many of the manufacturing steps associated with conventional production methods.
This manufacturing approach offers a fundamentally different level of design freedom. Traditional manufacturing processes often require designers to adapt component geometries to machining, forming, or joining constraints. With additive manufacturing, many of these restrictions can be reduced or eliminated, allowing engineers to focus more directly on the functional requirements of the heat treatment application.
For induction heating, this means that the geometry of the inductor can be tailored more closely to the desired electromagnetic field distribution and heating characteristics. As a result, component design, process requirements, and performance objectives can be aligned more effectively.
Another important advantage is the ability to manufacture inductors as monolithic components. Instead of assembling multiple individual parts, the inductor can be produced in a single piece. This eliminates joints that may act as potential mechanical weak points while also enabling the integration of internal features, such as cooling channels. These channels can follow complex three-dimensional paths that would be difficult or impossible to realize with conventional manufacturing methods, enabling more targeted and efficient thermal management.
Impact on Induction Heating Performance
The increased design freedom enabled by additive manufacturing translates directly into improved process performance. When the geometry of the inductor is closely matched to the component, the electromagnetic field can be shaped more precisely. This allows for a more uniform temperature distribution, which is essential for achieving consistent material properties in heat treated parts.
Inductor with spray cooling | Image Credit: PROTIQ
Optimized geometries also improve the coupling of energy into the workpiece. In practical terms, this means that the required heating energy can be delivered more efficiently, often resulting in shorter cycle times. At the same time, improved cooling concepts help stabilize the process by keeping the inductor within its operating limits, even under demanding conditions.
Because additive manufacturing allows components to be reproduced with high accuracy, it also supports consistent process results. Compared to manually fabricated coils, this reproducibility reduces variability and contributes to overall process stability. The absence of soldered or welded joints can further increase service life, as common failure mechanisms are eliminated by design.
Copper in Additive Manufacturing: From Challenge to Application
Copper is the preferred material for induction coils due to its high electrical conductivity. However, its processing in laser-based additive manufacturing systems has long been considered challenging. The high reflectivity of copper and its thermal conductivity make it difficult to achieve stable and efficient melting during the build process.
In recent years, these challenges have been addressed through advances in machine technology, laser systems, and material development. Today, it is possible to manufacture copper components with properties suitable for demanding industrial applications, including conductivity levels comparable to conventional materials.
Despite this progress, successful implementation still requires a detailed understanding of both material behavior and process conditions. The interaction between geometry, material properties, and manufacturing parameters must be carefully considered to ensure that the final component meets both functional and mechanical requirements.
Companies such as PROTIQ have developed extensive experience in processing pure copper by additive manufacturing. This knowledge helps ensure stable production processes and application-oriented solutions for demanding industrial components like inductors.
Bridging Design and Reality Through Simulation and Experience
Simulation tools are an important element in the development of modern inductors. They provide insights into electromagnetic field distribution and thermal behavior, allowing engineers to evaluate and optimize designs before manufacturing.
However, simulation alone cannot fully predict how a component will perform under real operating conditions. Factors, such as material characteristics, surface quality, and manufacturing tolerances, can influence actual results. For this reason, experience in both additive manufacturing and induction applications remains essential.
In practice, effective inductor development is based on a combination of simulation, engineering expertise, and manufacturing know-how. This integrated approach helps ensure that theoretical designs can be translated into reliable solutions for industrial use.
Typical Applications in Heat Treating
The advantages of additively manufactured inductors become particularly evident in applications where conventional designs reach their limits. This is often the case in the heat treatment of components with complex geometries or varying cross-sections, where uniform heating is difficult to achieve.
In surface hardening processes, for example, tailored coil geometries can improve the consistency of hardness profiles across critical areas. Similarly, localized hardening applications benefit from the ability to precisely confine the electromagnetic field to specific regions of the component.
Another important field of application involves components with limited accessibility or intricate features. Here, additive manufacturing allows the realization of coil designs that can be adapted closely to the part geometry, enabling effective heating in areas that are difficult to reach with conventional inductors.
These application scenarios illustrate how additive manufacturing expands the solution space in induction heating, particularly for tasks that require a high degree of customization.
From Technology to Industrial Practice
While additive manufacturing offers significant opportunities, its successful use in induction heating depends on several factors. Material selection, manufacturability, and process stability must all be considered from the outset. Not every theoretically optimal design can be produced reliably, and design decisions must account for the specifics of the additive process.
Equally important is a deep understanding of the application itself. The requirements of the heat treat process, the properties of the component, and the desired outcomes must all be reflected in the inductor design.
In practice, additive manufacturing is not always the only or best solution. Depending on the application, a combination of conventionally manufactured and additively produced features can provide the most effective balance between performance, manufacturability, and cost.
This is where manufacturing expertise becomes critical. Companies like PROTIQ support clients in evaluating which parts of an inductor benefit from additive manufacturing and which may be better suited to conventional production methods. By combining process knowledge, material expertise, and industrial manufacturing capabilities, innovative designs can be translated into reliable and economically viable components.
Application-Driven Inductor Design
Additive manufacturing represents a shift in how induction coils are conceived and realized. By removing many of the constraints associated with conventional manufacturing, it enables a more direct alignment between design and function.
For heat treat operations, this opens up new possibilities for improving efficiency, quality, and reliability. Instead of adapting processes to the limitations of available coil geometries, inductors can be tailored to the specific requirements of the application.
As the technology continues to mature, additively manufactured inductors are likely to become an increasingly important element in advanced heat treat processes. Their successful application, however, depends not only on access to manufacturing technology but also on a comprehensive understanding of materials, processes, and application context.
About The Author:
Max Wissing Technology Manager PROTIQ
Max Wissing is the technology manager for 3D printing at PROTIQ with nearly a decade of industry experience. He holds a degree in mechanical engineering, specializing in the optimization of 3D-printed induction coils.
Ask The Heat Treat Doctor® has returned to bring sage advice to Heat Treat Today readers and to answer your questions about heat treating, brazing, sintering, and other types of thermal treatments as well as questions on metallurgy, equipment, and process-related issues. In this Technical Tuesday installment, Dan Herring explores practical guidelines for getting heat treatment right the first time, every time, in the first part of a series inspired by the work of Jon L. Dossett. He outlines seven keys to success in heat treating and the two questions design engineers must answer about what a component must endure in service and how it will be made. He then examines the most common specification mistakes, including unrealistic hardness, case depth, and tolerance requirements, and shows how carbon content, section size, mass effect, and commercially achievable tolerances determine whether a steel can be hardened to specification.
This informative piece was first released in Heat Treat Today’sSeptember 2026 People of Heat Treat print edition.
In our day-to-day work, most of us face the challenge of meeting production demands while navigating tight manufacturing deadlines in an ever-changing materials and manufacturing landscape. Heat treatment can be defined as the controlled application of time, temperature, and atmosphere to produce a predictable change in the internal structure (i.e., microstructure) of a material, resulting in the desired metallurgical, mechanical, physical, and other properties we desire. There is, however, an alternate and equally important definition of heat treating: getting the job done right the first time — every time.
In this short series, we will examine practical guidelines to help make that objective a reality. Let’s learn more.
7 Keys to Success in Heat Treating
To accomplish this goal, we must be able to meet the seven key considerations in heat treating to ensure both our success and survival (Herring 2014a, 2014b, 2015):
To know, metallurgically, what you want to accomplish.
To be able to predict the outcome of a heat treatment operation.
To have repeatability built into the process.
To get the most out of the equipment you have and to use state-of-the-art heat treating equipment whenever possible.
To be aware of how changes to our manufacturing operations influence the outcome of a given heat treatment process or series of processes.
To not compromise on quality.
To know our costs and understand our profitability.
Challenges Faced by Today’s Engineers
In the design of any engineered component, it is necessary to fully understand and address two key questions that design engineers working with metallurgists are often best qualified to answer (Herring 2014a, 2015, 2017):
What must the component endure during service (i.e., what are the product requirements)? To answer this question, consider the following: What are the rigors of the application, and what is the design life? Must the component part provide premier service, or is there an adequate design life involved (i.e., will other factors end its service long before its useful life is expended)? What loading, lubricants, temperature, and contaminants are involved? What other service and performance aspects specific to the product must also be factored into the selection process?
How will the component part be made (i.e., what are the process requirements)? Consider the following: How will its basic form be generated, and how will it be heat treated — if at all? Will it be important to introduce particular mechanical properties? If so, how (i.e., by heat treatment or by mechanical means)? Is geometry or surface finishes important? Will special coatings be used? Is dimensional control (including stability at temperature) an issue? What other processing aspects specific to the product must be considered?
How We Achieve Our Goals
Experienced heat treaters often point to the most common mistakes made by design engineers and/or their clients, that is, selecting materials, defining and understanding the limitations of the requested heat treatment processes, and specifying realistic outcomes from heat treating.
These include, for example, the desired hardness, case depth, and dimensional tolerances. These issues generally result from a failure to recognize the differences in the material’s chemical composition and form (e.g., wrought or powder metallurgy, castings, forgings). The design engineer should also understand the mill processing methods used to produce the material.
Often, the tolerances for the specified heat treatment properties are either too aggressive, too ambiguous, or too restrictive from a real-world standpoint. Here are a few basic metallurgical guidelines that can, from a practical standpoint, help avoid these problems (Herring 2014a, 2015; Dossett 2007, 2026).
Steel Selection
Table A. Carbon Content vs. Hardness for Different Martensite Levels (Dossett 2007)
Problems in specifying the proper steel grade for a particular application generally involve choosing a steel grade that cannot be hardened to the specification and/or specifying a surface or core hardness range that is too restrictive. For example, Table A provides a guideline for the maximum surface hardness achievable using induction or flame hardening treatments. The maximum obtainable hardness is a function of the carbon content of the steel being used.
If the material selected is 4140H with a carbon range of 0.37–0.44%, we would expect the surface to be approximately 99.9% martensite after quenching. Thus, the expected as-quenched hardness would fall in the range of 54–58 HRC for all the heats of this steel. However, the ability to achieve this hardness depends on the severity of quenching, the quenchant used, the quench tank design, and the adequate removal of surface decarburization that might be present on the wrought steel itself.
Table B. Maximum Surface Hardness as a Function of Section Size (Chandlar 1995)Table C. Mass Effect on Maximum Surface Hardness: (Oil) Quenched 4140 Steel (0.40%C) (Bethlehem Steel Company 1949)
By contrast, in the case of furnace heat treatment, the maximum attainable surface hardness depends both on steel’s carbon content and its hardenability. The maximum section size (Table B) and effect of mass (Table C) are shown for several steel grades based on oil quenching. The commercially accepted range for surface hardness after tempering is ± 2.5 HRC points or ± 20 BHN points (Table D).
Table D. Commercially Desired Print Specification Tolerances for Properly Specified Materials
Next month we will review steel hardenability and how to determine the expected core hardness range.
This series was motivated by and contains insightful content from Jon L. Dossett who has granted permission. Jon’s distinguished career includes commercial heat treating involvement, extensive teaching career at ASM, and his work as editor of several volumes of the ASM Handbook series.
References
Bethlehem Steel Company. 1949. Modern Steels and Their Properties. Handbook 268. Bethlehem, PA: Bethlehem Steel Company.
Chandlar, Harry, ed. 1995. Heat Treater’s Guide: Practices and Procedures for Irons and Steels. Materials Park, OH: ASM International.
Dossett, Jon. 2007. “Make Sure Your Specified Heat Treatment Is Achievable.” Heat Treating Progress (March/April).
Dossett, Jon. 2025. Private conversation.
Herring, Daniel H. 2014a. Atmosphere Heat Treatment. Vol. 1. Troy, MI: BNP Media Group II.
Herring, Daniel H. 2014b. “Industry 4.0 and the 7 Key Considerations in Heat Treating.” Industrial Heating (September).
Herring, Daniel H. 2015. Atmosphere Heat Treatment. Vol. 2. Troy, MI: BNP Media Group II.
Herring, Daniel H. 2017. “The Relevance of Metallurgy in Engineering and Manufacturing.” Industrial Heating (November).
About the Author
Dan Herring “The Heat Treat Doctor®” The HERRING GROUP, Inc.
Dan Herring has been in the industry for over 50 years and has gained vast experience in fields that include materials science, engineering, metallurgy, new product research, and many other areas. He is the author of six books and over 700 technical articles.
Ask The Heat Treat Doctor® ha regresado para ofrecer consejos sabios a los lectores de Heat Treat Today y responder sus preguntas sobre tratamiento térmico, soldadura fuerte (brazing), sinterizado y otros tipos de tratamientos térmicos, así como preguntas sobre metalurgia, equipos y problemas relacionados con los procesos. En esta entrega de Technical Tuesday, Dan Herring explora lineamientos prácticos para lograr un tratamiento térmico correcto desde la primera vez, todas las veces, en la primera parte de una serie inspirada en el trabajo de Jon L. Dossett. Presenta siete claves para el éxito en el tratamiento térmico y las dos preguntas que los ingenieros de diseño deben responder sobre lo que un componente debe soportar en servicio y cómo se fabricará. Después examina los errores de especificación más comunes, entre ellos requisitos poco realistas de dureza, profundidad de capa y tolerancias, y muestra cómo el contenido de carbono, el tamaño de sección, el efecto de la masa y las tolerancias comercialmente alcanzables determinan si un acero puede endurecerse conforme a la especificación.
Este artículo informativo se publicó por primera vez en Heat Treat Today’sSeptember 2026 People of Heat Treat print edition.
Si tiene comentarios o preguntas sobre este artículo, háganoslo saber en: editor@heattreattoday.com.
En nuestro trabajo diario, la mayoría enfrentamos el desafío de cumplir con las demandas de producción mientras manejamos plazos de procesamiento ajustados en un panorama de materiales y manufactura en constante cambio. El tratamiento térmico puede definirse como la aplicación controlada de tiempo, temperatura y atmósfera para producir un cambio predecible en la estructura interna (es decir, la microestructura) de un material, dando como resultado las propiedades metalúrgicas, mecánicas, físicas y otras propiedades que deseamos. Sin embargo, existe una definición alterna e igualmente importante del tratamiento térmico: “hacer bien el trabajo desde la primera vez, todas las veces”.
En esta breve serie, examinaremos lineamientos prácticos para ayudar a hacer realidad ese objetivo. Conozcamos más.
7 claves para el éxito en el tratamiento térmico
Para alcanzar este objetivo, debemos ser capaces de cumplir con siete consideraciones clave del tratamiento térmico para asegurar tanto nuestro éxito como nuestra supervivencia (Herring 2014a, 2014b, 2015):
Saber, desde el punto de vista metalúrgico, lo que se desea lograr.
Ser capaz de predecir el resultado de una operación de tratamiento térmico.
Incorporar repetibilidad en el proceso.
Obtener el máximo provecho del equipo disponible y utilizar equipos de tratamiento térmico de última generación siempre que sea posible.
Ser conscientes de cómo los cambios en nuestras operaciones de manufactura influyen en el resultado de un proceso de tratamiento térmico determinado o de una serie de procesos.
No comprometer la calidad.
Conocer nuestros costos y comprender nuestra rentabilidad.
Desafíos que Enfrentan los Ingenieros de Hoy
En el diseño de cualquier componente de ingeniería, es necesario comprender plenamente y abordar dos preguntas clave que los ingenieros de diseño que trabajan con metalurgistas suelen estar mejor capacitados para responder (Herring 2014a, 2015, 2017):
¿Qué debe soportar el componente durante el servicio (es decir, ¿cuáles son los requisitos del producto?) Para responder esta pregunta, considere lo siguiente: ¿Cuáles son las exigencias de la aplicación y cuál es la vida útil del diseño? ¿Deberá el componente proporcionar un servicio de primera calidad o existe una vida útil de diseño adecuada (es decir, ¿otros factores pondrán fin a su servicio mucho antes de que se agote su vida útil?) ¿Qué cargas, lubricantes, temperaturas y contaminantes están involucrados? ¿Qué otros aspectos de servicio y desempeño específicos del producto también deben considerarse en el proceso de selección?
¿Cómo se fabricará el componente (es decir, ¿cuáles son los requisitos del proceso?) Considere lo siguiente: ¿Cómo se generará su forma básica y cómo se tratará térmicamente si es que se realizará un tratamiento térmico? ¿Será importante introducir propiedades mecánicas específicas? De ser así, ¿cómo? (es decir, ¿mediante tratamiento térmico o por medios mecánicos? ¿Es importante la geometría o los acabados superficiales? ¿Se utilizarán recubrimientos especiales? ¿Es importante el control dimensional (incluida la estabilidad a temperatura)? ¿Qué otros aspectos de procesamiento del producto deben considerarse?
Cómo Alcanzamos Nuestros Objetivos
Los especialistas experimentados en tratamiento térmico suelen señalar los errores más comunes cometidos por los ingenieros de diseño y/o sus clientes, es decir, la selección de materiales, la definición y comprensión de las limitaciones de los procesos de tratamiento térmico solicitados y la especificación de resultados realistas del tratamiento térmico. Estos incluyen, por ejemplo, la dureza deseada, la profundidad de capa y las tolerancias dimensionales. Estos problemas generalmente se deben a no reconocer las diferencias en la composición química y la forma del material (por ejemplo, material trabajado o pulvimetalurgia, piezas fundidas, piezas forjadas). El ingeniero de diseño también debe comprender los métodos de procesamiento en planta utilizados para producir el material. Con frecuencia, las tolerancias para las propiedades especificadas del tratamiento térmico son demasiado exigentes, demasiado ambiguas o restrictivas desde un punto de vista práctico. A continuación, se presentan algunos lineamientos metalúrgicos básicos que, desde un punto de vista práctico, pueden ayudar a evitar estos problemas (Herring 2014a, 2015; Dossett 2007, 2026).
Selección del acero
Tabla A. Contenido de carbono vs. Dureza para Diferentes Niveles de Martensita (Dossett 2007)
Los problemas al especificar el grado de acero adecuado para una aplicación particular generalmente implican elegir un grado de acero que no puede endurecerse conforme a la especificación y/o especificar un intervalo de dureza superficial o del núcleo demasiado restrictivo. Por ejemplo, la Tabla A proporciona una guía sobre la dureza superficial máxima que se puede alcanzar mediante tratamientos de endurecimiento por inducción o por flama. La dureza máxima que puede obtenerse depende del contenido de carbono del acero utilizado.
Si el material seleccionado es 4140H con un intervalo de carbono de 0.37-0.44%, esperaríamos que la superficie fuera aproximadamente 99.9% martensita después del temple. Por lo tanto, la dureza esperada en condición de temple estaría en el intervalo de 54-58 HRC para todas las coladas de este acero. Sin embargo, la capacidad de alcanzar esta dureza depende de la severidad del temple, el medio de temple utilizado, el diseño del tanque de temple y la eliminación adecuada de la descarburización superficial que pudiera estar presente en el propio acero trabajado.
Tabla B. Dureza superficial máxima en función del tamaño de sección (Chandlar 1995)Tabla C. Efecto de la masa sobre la dureza superficial máxima: acero 4140 (0.40%C) templado en aceite (Bethlehem Steel Company 1949)
Por el contrario, en el caso del tratamiento térmico en horno, la dureza superficial máxima alcanzable depende tanto del contenido de carbono del acero como de su templabilidad. El tamaño máximo de sección (Tabla B) y el efecto de la masa (Tabla C) se muestran para varios grados de acero templados en aceite. El intervalo comercialmente aceptado para la dureza superficial después del revenido es de ± 2.5 puntos HRC o ± 20 puntos BHN (Tabla D).
Tabla D. Tolerancias de especificación en plano comercialmente deseadas para materiales correctamente especificados
El próximo mes revisaremos la templabilidad del acero y cómo determinar el intervalo esperado de dureza del núcleo.
Esta serie surgió gracias a Jon L. Dossett, quien ha otorgado su autorización y contiene información valiosa aportada por él. La distinguida carrera de Jon incluye participación en el tratamiento térmico comercial, una extensa carrera docente en ASM y su trabajo como editor de varios volúmenes de la serie ASM Handbook.
Referencias
Bethlehem Steel Company. 1949. Modern Steels and Their Properties. Handbook 268. Bethlehem, PA: Bethlehem Steel Company.
Chandlar, Harry, ed. 1995. Heat Treater’s Guide: Practices and Procedures for Irons and Steels. Materials Park, OH: ASM International.
Dossett, Jon. 2007. “Make Sure Your Specified Heat Treatment Is Achievable.” Heat Treating Progress (March/April).
Dossett, Jon. 2025. Private conversation.
Herring, Daniel H. 2014a. Atmosphere Heat Treatment. Vol. 1. Troy, MI: BNP Media Group II.
Herring, Daniel H. 2014b. “Industry 4.0 and the 7 Key Considerations in Heat Treating.” Industrial Heating (September).
Herring, Daniel H. 2015. Atmosphere Heat Treatment. Vol. 2. Troy, MI: BNP Media Group II.
Herring, Daniel H. 2017. “The Relevance of Metallurgy in Engineering and Manufacturing.” Industrial Heating (November).
Acerca del Autor
Dan Herring “The Heat Treat Doctor®” The HERRING GROUP, Inc.
Dan Herring lleva más de 50 años en la industria y ha adquirido una vasta experiencia en áreas que incluyen ciencia de materiales, ingeniería, metalurgia, investigación de nuevos productos y muchas otras. Es autor de seis libros y de más de 700 artículos técnicos.
In this Technical Tuesday installment,Heat Treat Today founder and publisher Doug Glenn sat down with Steelhead Technologies CEO Jeff Halonen to discuss the company’s recent acquisitions of Visual Shop and Bluestreak. Learn what the acquisitions mean for current users, including support and migration timelines, and how Steelhead plans to bring decades of heat treat-specific expertise into its ERP platform.
Heat Treat Today founder and publisher Doug Glenn spoke with Steelhead Technologies CEO Jeffrey Halonen about the acquisitions and what commercial heat treaters can expect in the coming years.
The Companies and Their Software
Steelhead Technologies provides an all-in-one AI-powered ERP platform designed for job shops and manufacturing operations, connecting production management with quality, specification compliance and tracking, scheduling, accounting, CRM, reporting, and other business functions.
Halonen called Visual Shop one of the first commercially available systems built specifically for the heat treat market. Visual Shop has served process-oriented job shops for more than 30 years. Approximately 150 enterprises currently use Visual Shop, about half of which are commercial heat treaters. The ERP system was developed for metal finishing, heat treating, coatings, and related industries, with heat treat functionality including furnace-load tracking, specifications and certifications, process temperatures and times, order tracking, shipping, and invoicing.
Bluestreak has similarly deep roots in the industry. The QMS and MES platform was initially developed for heat treating and focuses on production workflow, integrated quality management, traceability, and compliance documentation. It has approximately 90 clients, about 60% of which are commercial heat treaters. “Bluestreak is a QMS and MES,” Halonen said. “They’re more specialized on the heat treating.”
The Acquisition Timeline
Although Steelhead acquired Visual Shop and Bluestreak within weeks of each other, Halonen said the deals developed separately, with different circumstances behind them and their timing largely coincidental. With Visual Shop, Halonen said the age and architecture of the software meant significant development would eventually require rebuilding the product. “It was just at a juncture where there’s either a tremendous amount of investment — many, many millions of dollars — to start from scratch, essentially, on a brand new product, or we could provide a structured transition over to a more modern system where there’s a definitive path,” he said.
Bluestreak, by comparison, was growing and had strong client retention. Retirement considerations for Bluestreak president and founder Todd Wenzel also played a role. Bluestreak also brings years of heat treat-specific software development, particularly around specifications, certifications, furnace compliance, and other quality requirements. “Bluestreak is on its fourth generation,” Halonen commented. “It’s been working with heat treaters for many, many years.”
Halonen acknowledged that the experience of these two software leaders in the space is important as Steelhead expands its presence in the heat treat industry. “Especially with commercial heat treating, there’s a tremendous amount of nuance,” he said. “We need to approach this with humility.”
Next Steps for Visual Shop and Bluestreak Clients
For existing clients, neither system is disappearing immediately. Visual Shop and Bluestreak are now under the Steelhead umbrella, but their existing support teams remain in place. “For Visual Shop, right now nothing changes,” Halonen said. “You have the same product, call the same exact team.”
The longer-term picture is different. Steelhead is targeting the end of 2027 for sunsetting support for Visual Shop. Many Visual Shop users have perpetual licenses, and Halonen emphasized that retiring support does not mean those users will suddenly lose access to the software. The primary change will involve continued support.
Bluestreak has a longer runway, with its timeline extending into 2028. Its existing support team also remains in place. At the same time, Steelhead intends to bring heat treat-specific functionality developed within Bluestreak into its own platform. “We’re working very closely as a single team to provide all the features that Bluestreak has developed over the years that are great for heat treaters and pulling those into Steelhead,” Halonen said.
One point is clear for users of both products: future software development will be focused on Steelhead’s technology. “All proactive R&D investment in technology is going into the Steelhead platform,” Halonen said.
Cost Considerations
For Visual Shop users considering a transition to Steelhead, price will be an important part of the decision. Halonen acknowledged that Steelhead carries a substantially higher software price.
Steelhead argues that shops should compare total operating costs rather than software prices alone, including separate accounting or business software and employee time associated with order entry, invoicing, and other administrative processes. “What we’ve found, though, is that if you look at the cost of operating your business on Visual Shop — not just the dollars you pay for Visual Shop — you actually see a cost reduction for Steelhead,” Halonen said. Whether that calculation holds true will depend on the individual operation. Heat treaters will need to weigh software costs against staffing, current processes, ancillary systems, desired functionality, and implementation requirements.
For Bluestreak users, Halonen said the pricing gap between their current system and Steelhead is smaller, although a difference remains.
Migration and Support
The acquisitions could simplify one challenge for clients who choose to migrate to Steelhead: transferring existing data. Steelhead now has access to the source code and database structures of the acquired platforms, as well as the employees familiar with them. “The data you have in Visual Shop and the data you have in Bluestreak can be mapped over in a much more efficient, and much more granular, manner than otherwise would be,” Halonen said.
The Visual Shop and Bluestreak teams — approximately eight and nine people, respectively — remain in place to support existing products and assist with integrations or migrations. Together with Steelhead’s roughly 310 existing clients, the acquisitions bring the company’s total client base to approximately 550.
Halonen said Steelhead also intends to control the pace of implementations rather than taking on migrations faster than its teams can support them. “If we’re in a position where we’re not 100% confident that it’s going to be successful for our client, we’re going to use the calendar to our advantage and make sure we’re not overscheduling or overburdening,” he said.
Where Development Goes from Here
Steelhead’s long-term strategy is to combine heat treat-specific knowledge from the acquired companies with its broader ERP platform. For Halonen, that starts with the fundamentals heat treaters rely on every day. “How can I do furnace calibrations? How can I create this certification? What’s my operator’s experience going to be?” he said, describing the questions heat treaters bring to Steelhead. “They’re absolutely correct to focus on that.”
Steelhead also plans continued development of automation and AI tools, including its existing AI-assisted order entry and analytics. But Halonen said those capabilities depend on getting the underlying systems right first. “None of that works unless you have a rock solid foundation,” he said.
What Heat Treaters Should Know Going Forward
The acquisitions do not require Visual Shop or Bluestreak users to make an immediate software change, but they do establish a clearer direction for both platforms. Visual Shop is targeted for end of life at the end of 2027, while Bluestreak’s timeline extends into 2028. Existing support remains in place, while future R&D is being directed toward Steelhead.
For affected heat treaters, that creates a window to evaluate their options. Which heat treat-specific capabilities are essential? What other systems or manual processes operate alongside the current software? What data must be preserved? What will implementation require from employees? And what will each option cost when software and business processes are considered together?
Three platforms are now under one company, and the software landscape serving heat treaters has shifted. The next couple of years give shops time to determine what that shift should mean for their own operations.
This article was written by Heat Treat Today’s Editorial Team.
Jim Roberts of U.S. Ignition engages readers in a Combustion Corner column about the modes of heat transfer at play in the heat treating world — breaking down advection and thermal conduction, from how forced air movement drives heating and cooling in furnaces to how Fourier’s law governs heat flow through direct contact, setting the stage for next month’s look at convection and radiation.
This editorial was first released in Heat Treat Today’sAugust 2026 Annual Automotive Heat Treating print edition.
A furnace guy walks into a heat treat facility and asks, “tropos metadosis thermotitas?” The furnace operators stare and say, “What are you saying? It’s all Greek to me!” But many of us know what it means: What mode of transfer? And that was the question of the last article where we looked at an intro to thermodynamics. This set us up for discussions on the four modes of heat transfer, a non-stop set of interactive processes that we then refine for our use in the heat treating world.
In that earlier discussion, we explained that there are several modes involved in heat transfer. Some are so simple to describe, but there may be several modes working at the same time to target the heat transference we seek. Modes of heat transfer and the Laws of Thermodynamics differ. Think of modes as the actual physical properties of heat transfer and thermodynamics that we can see and feel. The laws are the calculations and theory that allow us to check and produce the heat that is needed or to prove how much we need.
Our first mode of heat transfer is advection. Advection is the mechanism of thermal transfer that occurs when the thermal energy is transferred or transported from one space or object via the movement and the motion of a fluid. Pure convection, in the scientific sense, is strictly the heat transfer between heated bodies by gravitational lift or natural fluid movements.
In other words, heat rises… right? We’ve all heard it, witnessed it in a campfire or elsewhere. Advection is when the transfer media, mostly hot gases, is forced mechanically to swirl around and the item we desire to heat or cool. Speaking of heat transfer, we cannot forget that the door swings both ways. We can affect heat transfer from the standpoint of cooling things down too, and at that point, we discover that the hot gases or heat exchangers with air of liquid are using advection to pull the heat out. The plunge cool function of many furnaces relies on advection to pull the heat out of the parts at a controlled rate to cause a metallurgical change. So, the same laws apply, just in reverse!
One of the easiest ways to remember this difference is that advection actually adds energy to the process. It may be in the form of a blower providing combustion air for a burner, which creates the swirl of gases that are providing the heat transfer to the parts. Or, think of a fan pulling heat from a circuit board of electrical components. Advection is actually forced convection. If you have a modern convection oven or an air fryer, it is not really a convection oven. It’s an advection oven in the scientific world, since the fans involved are adding energy to move the fluid (air/gas) around those chicken wings and fries. The concern over this kind of added energy is in part what makes Data Centers such a volatile topic.
This leads us to our second heat transfer mode, thermal conduction. Thermal conduction is the transfer of heat by direct contact of two objects where there is a differential in temperature and energy. In other words, the temperature difference between two objects is the mechanism for heat transfer. Energy wants equilibrium, so it will always try to bring an item to its temperature by maintaining contact. It can be identified as thermal diffusion in Fourier’s law for heat conduction.
Fourier’s law states that eventually, through contact, the handle on the cooking pot will match the temperature of the pot surface because it is conducting the heat into that handle via thermal conduction. These types of considerations take place during calculations for furnace design, engine components, or household items; anything with a heat differential must be accounted for in our everyday lives.
As they say in the old country: choris thermotita, den yparchei ergo. Without heat, there is no work. That’s the loose translation, but it points out that we need to have all the components for heat transfer to be working for us to do this wonderful work called heat treating. And that shouldn’t be Greek to us.
Next month we will tackle convection and radiation.
About The Author:
Jim Roberts President US Ignition
Jim Roberts president at U.S. Ignition, began his 45-year career in the burner and heat recovery industry focused on heat treating specifically in 1979. He worked for and helped start up WB Combustion in Hales Corners, Wisconsin. In 1985 he joined Eclipse Engineering in Rockford, IL, specializing in heat treating-related combustion equipment/burners. Inducted into the American Gas Association’s Hall of Flame for service in training gas company field managers, Jim is a former president of MTI and has contributed to countless seminars on fuel reduction and combustion-related practices.
Heat Treat Today launches a new contributing experts series on emerging technologies reshaping heat treat operations. In this first installment, Zach Menard, CEO and co-founder of HRC Labs, demystifies deep neural networks (DNNs)— a technology quietly used in industrial settings for years — and explains how they turn accumulated furnace cycles, recipes, and quality records into predictive models that help heat treaters develop new recipes, minimize distortion, and cut cycle times.
This informative piece was first released in Heat Treat Today’sAugust 2026 Annual Automotive Heat Treating print edition.
Large language models (LLMs) have dominated recent conversations around artificial intelligence, but they are only one application of deep neural networks (DNNs). Years before DNNs were applied to human language, they had been deployed in industrial settings to optimize processes, improve yield, and support quality control.
These same, well-established approaches can be applied to heat treatment by learning relationships between process inputs — such as temperature, time, atmosphere, and alloy composition — and resultant metallurgical properties like hardness, distortion, or case depth.
It’s the first word in the acronym, DNN, that makes this learning possible. The neural network is said to be “deep” because of its many successive layers of neurons. Each neuron on its own is very simple. All it can do effectively is multiply and add together the numbers it has received from earlier neurons. However, when this process is repeated across many layers, the overall network is able to learn complex relationships that influence the heat treatment process.
By training on historical production data, DNNs can transform years of accumulated process knowledge into predictive models. Patterns that may otherwise remain buried across thousands of furnace cycles, recipes, and quality records can be captured quantitatively by the model itself.
In this way, operational experience and historical records become structured, reusable intelligence that can aid decision-making. Examples include when heat treaters are developing a new recipe, considering how to minimize distortion, or lowering cycle times.
As heat treatment operations continue accumulating larger volumes of process data, applying DNNs to this data offers a clear path toward AI-assisted process optimization, operational intelligence, and more adaptive heat treatment systems.
About the Author
Zachary Menard CEO and Co-Founder HRC Labs
Zachary (Zach) Menard is the CEO and co-founder of HRC Labs, an industrial AI company focused on process optimization and decision support for heat treatment. He holds a B.S. in physics from Vanderbilt University with a background in computational physics and machine learning research.
Ask The Heat Treat Doctor® has returned to bring sage advice to Heat Treat Today readers and to answer your questions about heat treating, brazing, sintering, and other types of thermal treatments as well as questions on metallurgy, equipment, and process-related issues. In this Technical Tuesday installment, Dan Herring explores the fundamentals of vacuum oil quenching — the three stages of oil quenching, the properties that make oil an effective quenching medium, and the ways pressure control, oil circulation, and temperature can be used to minimize part distortion — and offers step-by-step guidance on properly conditioning and degassing vacuum quench oil to ensure consistent, repeatable results.
This informative piece was first released in Heat Treat Today’sAugust 2026 Annual Automotive Heat Treating print edition.
Oil quenching in vacuum furnaces is a technology that has been around for over 65 years. The popularity of oil as a quench medium is due to its excellent performance and stability over a broad range of operating conditions. Proper application, testing, and conditioning of the oil are necessary to ensure its effectiveness. Let’s learn more.
For many, the choice of oil is not only due to metallurgical transformation and resultant properties it can achieve, but also to a number of other factors, including:
The first criterion that any quenchant must meet is its ability to approach an ideal quenching medium.
Figure 1a-b. Three stages of oil quenching
Regardless of the type of liquid (brine, water, polymer, oil, molten salt, or air mist), the ideal quenching medium (Figure 1) is one that would exhibit high initial quenching speed in the critical hardening range (Stages 1 and 2) and a slow final quenching speed through the lower temperature range (Stage 3). Thus, the ideal quenchant is one that exhibits little or no vapor blanket stage, a rapid but controlled nucleated boiling stage, and a slow cooling rate during convective cooling.
The high initial cooling rates allow for the development of full hardness by ensuring the steel misses the “nose” of the time-temperature-transformation diagram (i.e., quenching faster than the so-called critical transformation rate). This is followed by cooling at a slower rate beginning at the time the steel is forming martensite, which allows for better stress equalization so that the potential for distortion and cracking is reduced.
When conventional quenching oils are used, the duration of Stage 1 is longer, the cooling rate in Stage 2 is considerably slower, and the duration of Stage 3 is shorter. As such, the “quenching power” of oil is far less drastic than other quenchants. Water and water-based quenchants exhibit high initial cooling rates. Unfortunately, because of water’s low boiling point, this fast cooling persists until the steel is cooled to below 300°F (150°C). As most steels have formed or are forming martensite by this point, stresses are given little time to equalize. Thus, water is typically limited to low hardenability materials and relatively simple geometries.
Oil has a major advantage over water or polymer due to its higher boiling range. A typical oil has a boiling range between 450°F (230°C) and 900°F (480°C). This causes the slower convective cooling stage to start sooner, enabling the release of transformation stresses. Oil, therefore, is able to quench intricate shapes and high hardenability alloys successfully.
As it is heated, oil has a proportional drop in viscosity. This allows the quenchant to move more freely, increasing, in general, the tendency to break the vapor blanket layer. The nucleate boiling stage is not drastically altered by changes in bath temperature. The cooling rate in the convection stage, however, will slow as the bath temperature increases. This is advantageous for obtaining a slower rate of cooling through the austenite-to-martensite transformation range.
In general, as the temperature of a quenching oil increases, the overall quenching rate increases. Practical heat transfer coefficient (α) values are in the 1,000 to 2,500 W/m²K range depending on oil characteristics and degree of agitation. Peak α values are in the order of 4000 to 6000 W/m²K, or a cooling rate greater than 100°C/sec (180°F/sec).
Figure 2. Typical commercial heat treat load | Image Credit: The HERRING GROUP, Inc.Figure 3. Die cutting punches benefiting from controlling the pressure over the oil | Image Credit: The HERRING GROUP, Inc.
The use of vacuum oil quenching has been found to reduce distortion in many components including gears, pinions, and shafts (Figure 2). Oil quench vacuum systems also offer an attractive alternative to conventional atmosphere oil quenching, given their ability to vary a quench related variable not otherwise possible, namely controlling the pressure over the oil (Figure 3). This technique can be used to extend the range of part cross sections and materials that can be successfully hardened (Herring 1987, Sugiyama and Uchigaito 1987).
Pressure control along with oil temperature and oil circulation improves the predictability of distortion. The lower pressure allows for longer “vapor blanket” stages and a somewhat long “vapor transfer” stage, due to the reduced boiling point of the oil. This may reduce distortion and provide the desired hardness if the material’s transformation ranges are accommodating.
Distortion minimization methods have been used in combination with changes to flow characteristics. Some manufacturers pull oil down through the workload as opposed to pushing it upward. Also, oils formulated for vacuum service typically have a low vapor pressure, allowing them to be easily degassed.
Finally, vacuum systems do not permit the buildup of water in the quench tanks. In a vacuum furnace system, where vacuum is used to process the work or purge the quench environment, moisture will be removed as the system is evacuated and the oil circulated. Circulating the oil carries any moisture to the oil surface, where it vaporizes and is removed by the vacuum pumping system.
Maintaining Your Vacuum Quench Oil
One of the aspects of vacuum oil quenching that is seldom documented is how to condition the quench oil. See “Step-By-Step Instructions for Conditioning and Degassing Vacuum Quench Oil” below.
Final Thoughts
As with all quenching, the key is to understand and control the key process variables. Proper selection of the type and use of oil under ideal conditions in a well-designed and well-maintained quench tank will ensure consistent and repeatable results.
Oil quenching should be applied in applications where its advantages outweigh its disadvantages and, as with all technologies, should be as completely understood as possible with respect to the performance requirements of the product so as to meet the application end use.
References
Brian Barlow. 2025. Private correspondence. Gasbarre Thermal Processing Solutions.
Herring, Daniel. H. 2002. “A Review of Factors Affecting Distortion in Quenching.” Heat Treating Progress Magazine. December. 2012. Vacuum Heat Treatment, Volumes I. BNP Media Group.
Herring, Daniel H. 2016. Vacuum Heat Treatment, Volume II. BNP Media Group.
Herring, Daniel H., Steven D. Balme. 2007. “Oil Quenching Technologies for Gears.” Gear Solutions. July.
Herring, D. H., Sugiyama, M., Uchigaito, M. 1986. “Vacuum Furnace Oil Quenching – Influence of Oil Surface Pressure on Steel Hardness and Distortion.” Industrial Heating Magazine. June.
Sugiyama, M., Uchigaito, M. 1987. “Controlling Oil Surface Pressure in Vacuum Oil Quenching.” Heat Treating Magazine. July.
About the Author
Dan Herring “The Heat Treat Doctor®” The HERRING GROUP, Inc.
Dan Herring has been in the industry for over 50 years and has gained vast experience in fields that include materials science, engineering, metallurgy, new product research, and many other areas. He is the author of six books and over 700 technical articles.
