August 2026 Volume 8

EQUIPMENT & TECHNOLOGY

THE EVOLUTION OF POWER SUPPLY TECHNOLOGY FOR INDUCTION FORGING SYSTEMS By Joe Stambaugh

I n modern forging operations, production targets continue to rise while energy costs, labor constraints, and equipment uptime requirements become increasingly critical. Induction heating systems have become the preferred method for heating billets and bars because they provide rapid, efficient, and repeatable heating. Behind every induction heating system is a power supply architecture that directly impacts reliability, operating costs, and production performance. More than twenty years ago, I authored a technical paper advocating for Silicon Controlled Rectifiers (SCRs) in the design and manufacture of induction forging heaters. At the time, contemporary analog control boards were simply too slow to protect faster emerging transistor technologies. To overcome this limitation, Ajax TOCCO Magnethermic developed high-speed digital electronics, fiber-optic communications, and advanced protection networks. These innovations fully tamed and leveraged the inherent advantages of modern Insulated Gate Bipolar Transistors (IGBTs). For forging operations, temperature variation is more than an efficiency concern. Inconsistent billet temperatures can lead to poor die fill, increased press loads, accelerated die wear, and greater scrap rates. Modern induction systems powered by IGBT technology help maintain tighter temperature control and improved repeatability throughout production. Today, IGBTs have largely replaced SCRs in high-power switching applications globally. When purchasing induction heating equipment for forging, selecting the right power semiconductor is just as critical as the induction coil design itself. The Medium-Frequency Workhorse Medium-frequency induction heating—typically spanning from 1 kHz to 10 kHz—is the primary workhorse of the forging industry. It provides the deep thermal penetration required for bulk forging, billet heating, bar end heating, and many heating applications. To achieve maximum energy efficiency and system reliability within this band, engineers must balance raw power handling against rapid switching speeds. While legacy devices and ultra-fast alternatives each have their place, the IGBT has firmly established itself as the global industry standard for medium-frequency forging applications, delivering: • Higher Efficiency: Significantly lower operational and switching losses. • Compact Footprints: Smaller inverter designs that fit directly under induction coils. • Reduced Cooling: Minimal thermal management required due to low heat dissipation. • Broad Frequency Range: Seamless, stable operation across the entire medium-frequency spectrum.

• Multi-Band Capability: Single power supplies engineered to run across multiple frequency bands.

Figure 1: A traditional disc-type ("hockey puck") Silicon Controlled Rectifier (SCR) historically relied upon for high-power industrial switching.

Figure 2: A modern, high-capacity industrial IGBT module engineered for high-speed, voltage-controlled efficiency.

Technical Breakdown: Power Semiconductors Head to-Head To understand why the IGBT reigns supreme, we must look at how it compares to alternative silicon technologies across key operational parameters:

14 FIA MAGAZINE | AUGUST 2026