In my 40-plus years in the induction heating business, I can remember few (if any) instances where a buyer of induction equipment had the necessary expertise to help in specifying, evaluating, negotiating and managing the overall buying process.


Using the expertise of a consultant to help you purchase specialized induction equipment can provide many benefits. These include a more complete purchase specification; more qualified bidders; cost savings for the best value; detailed review of the offerings; and better understanding of the equipment acceptance, start-up and warranty details.

In the past, some major automotive plants, farm-equipment plants and first-tier truck and automotive suppliers had people within their organization who had some of this specialized knowledge. Some of them even had technical-support engineers that studied specialized equipment and helped the plants with specifications and evaluating the offerings. With downsizing, retirements and manufacturing outsourcing of complete assemblies, much of this help and advice is no longer available.


Investment in Expert Advice Can Return Dividends

Purchasing induction heating equipment can be a difficult task with a variety of unknowns and possible pitfalls for many organizations. Since induction heating is a very specialized process, it can require complex equipment combining electrical, mechanical, machine control and process monitoring to achieve a consistent process result. When a manufacturer needs to purchase this type of equipment, they generally need to rely on the expertise or the specialized knowledge of the companies that make this equipment. However, there is a lot of expertise available that is no longer attached to the equipment manufacturers.

Some of these experts include former VPs of sales and engineering, general managers, power-supply designers, and process and metallurgical experts. These specialists are available as consultants to large and smaller manufacturers that want help to buy, use or improve their induction heating equipment. Most of these consultants have been used by the induction heating equipment manufacturers, but the users of this equipment can take advantage of this help as well. For a relatively small investment, this assistance can be used to save money on the purchase of new equipment, get the best equipment for their needs from a company well suited to supply their requirements and review the details of what is being offered.

All of the companies that manufacture this specialized type of equipment have a wealth of expertise within their organizations. Much of this knowledge is gained from the experience of the particular products and processes with which they are most frequently involved. An example of this would be a company that is primarily engaged with induction melting, induction heating for forming or forging, or induction welding of tube and pipe. These companies may not have as much experience in induction heating for heat treatment or brazing. Their specific expertise can influence the design and efficiency of the products they build and offer for their customers.

Induction power supplies that are designed for melting, tube welding, mass heating, etc. may have different primary requirements than those designed for heat treating, brazing or other purposes. Some induction companies have more experience with small, higher-frequency power supplies (less than 50 kW), while some others have more experience with larger, medium-frequency power supplies (more than 50 kW). It is not common to find one company that has equal effectiveness with both. When a manufacturer needs to buy an induction heating machine, how can they sort out all of the important areas to consider and find the companies best suited to supply their needs?

We will focus on heat-treating equipment in this article since almost every requirement for heat treating requires a specific technical review. I will outline many of the areas that need to be clarified when buying induction heat-treating equipment. The materials, hardness pattern(s), part geometry, part mix, production rate and other details of every application must be reviewed to be sure the equipment offered will be suitable.


Standard Scanners May Not Be So Similar

If the equipment being considered is a “standard” machine, all of these details must be considered. If it is a standard machine with added automation or a custom-automated machine, it is even more important to consider all the details since this type of system will probably be less flexible than a standard machine alone. All of these machine possibilities may have a number of different power supplies from which to select. Many times when there are a number of different parts to process on a single machine the power supply will have to be a compromise between the best for one part requirement and the best for another.

If you are embarking on a quest to purchase a new induction heat-treating machine, the most common offering is a standard scanner. The following items still need to be evaluated:

•  Determine process requirements
•  Identify companies capable of providing equipment suited to your needs
•  Review quotes and determine best approach
•  Review quote details and responsibilities
•  Understand exactly what is being included (e.g., dual-quench manifolds with separate valves)
•  Revise quotes to include any changes necessary
•  Negotiate commercial and service details (terms, acceptance tests, service, training, warranty, etc.)
•  Order placement
•  Engineering review prior to manufacture
•  Project overview during design and manufacture
•  Machine runoff and acceptance
•  Installation and start-up
•  Final acceptance and final payment

An example of the variety of systems that can be offered is shown in the figures included in this article. The system requirement used was a 150-kW, 10-kHz dual-spindle induction scanning system suitable for handling up to 100 pounds of parts and tooling. I asked a number of companies that are involved in the U.S. market to provide a photo of their standard system. Shown are images of the equipment that the manufacturers offered. Some were able to meet the specified requirements and some were not.

In addition, we asked a number of other companies that did not offer photos. They all offer suitable equipment with each having their own levels of quality and sophistication. Some may be acceptable for your application, and others may be much more or less complex than needed. Each company will, of course, point out the reasons their product is best for your needs. There are many features and ways of accomplishing the desired results. Each of these systems includes: mechanical and quench systems; tooling and inductors; power supply; matching station and cooling system; machine controls and process monitoring; production process verification; and start-up, training and aftermarket support.


Sorting it Out

How do you decide which you need and which is the best value (not always the lowest price)? How do you evaluate the differences to decide which is best suited for your needs? Isone minimally acceptable and another excessively expensive with features you do not need? Although many of these standard products may meet the basic specifications, there can be many ways of accomplishing that result.

The details are too many to cover in this article but will be addressed in a subsequent work. Generally, the mechanical details can be heavy duty or lighter duty, provide ease of adjustment of inductors or lack of adjustment (both may be suitable for your needs). The method of scanning can vary as follows:

•  Parts move past the inductor on a stationary “tower” (Figs. 1-4)
•  Part, tooling and “tower” move past the coil through stationary bearings (Figs. 5 and 6)
•  Coil moves past the parts to be hardened (Figs. 7 and 8)

Each can have pros and cons depending on your application.

Quench recirculation and cooling systems can use different methods of recirculation, single- or dual-quench valves and manifolds, different volume of quench holding tanks, different heaters (or no heaters at all) and various methods of quench filtration. The power supply and matching capabilities can vary even though they may be stated as the same rating. Range and need for adjustment can vary along with the ease of accessing any needed adjustments.

Controlling and protecting the power supply and the operators should be reviewed, and cost and accessibility of components is important. The type of water-cooling and recirculating system offered for the power components can include different types of heat exchangers and methods of controlling the temperature as well as different duty-cycle ratings.


Custom and Automated Systems Can Vary Widely

If you are considering a custom or automated design, there are many additional details to resolve. For many years, I was involved in conceptualizing and quoting custom-designed machines. Many of these quotes were very general in nature, and details of many parts are not defined. If you are buying this type of machine, you should have the experience to ask about the things that are not defined. It is better for both parties to understand as much as possible about what is to be supplied before you place an order. This will avoid later “add-ons” and misunderstandings after an order is under way. These tend to be expensive and cause delays in design and build of the equipment.



There is expertise available to help buyers of induction heating equipment, and this is especially valuable if the equipment is to be used for heat treating. Independent consultants with many years of experience in concepts, processes, design, sales, quoting, power supplies and maintenance of induction heating equipment can help users and buyers. Their expense can be incurred only when needed, and they can free your employees to handle the need of your specific business.

Any costs associated with this help will be more than recovered by helping you secure the best value for the least cost, more versatility, better quality, fewer delays and misunderstandings, and more complete after-sale services.


For more information:  Contact Frank Wilson, Induction Heating Consultations, 1840 Roslyn Rd., Grosse Pointe Woods,  MI 48236; tel: 313-432-1602; e-mail: We can provide a consultant with specialized capability in metallurgy (induction requirements), machine concepts and proposals, sales, project management, power-supply design and technical service.

Automotive Focus

Ball-Stud Hardening Options

Of the many automotive ball-stud hardening options, how do you decide which is best for your requirements?

Many manufacturers use induction heating to harden automotive ball studs. Over the years, I have seen and sold many different types of induction heating machines for hardening ball studs. If you were to receive a number of proposals for this application, they may include the following choices:

•  Manual load/unload, lift and rotate (or scanner) machines
•  Multi-station lift and rotate machines with robot load/unload
•  Single- or  multi-station lift and rotate machines with horizontal indexing coil (some hardening patterns cannot be accomplished by lifting vertically into a heating coil) with or without robot load/unload (lifting may or may not be used)
•  Manual or automated load/unload indexing-table machine with horizontal indexing coil and an added temper station (no lifting is needed with this approach)
•  Manual or automated load/unload indexing-table machine with a channel-type coil and part rotation
•  Other possibilities 

All of these options have been used for this requirement, and all have very different considerations. Once you have decided which of the offers is suited for your needs, you need to evaluate the pros and cons of each offering. You can still compare the different areas of each machine since these are not necessarily similar. An example would be the ability to monitor the heating of each part. The different approaches can be heating one part at a time, two parts at a time in series or multiple parts at a time in the case of a channel-type coil. All of these can be perfectly suited to the requirement, but an experienced induction professional can help evaluate the things that separate the different approaches.

I recently helped a client with a different automotive transmission part, and we received three quotes from major U.S. induction companies. One offered a multi-station scanner with robot load/unload. One offered two scanners with a single robot to load and unload. The third offered an automated load/unload indexing-table machine. There were many other differences and prices varied widely. All were suitable for the production requirements.

The user had unique considerations beyond the details of each offer. The comparison was involved, and many issues were uncovered. The user finally decided to purchase the system that provided the best value, but it was not the lowest price.