MFDC Welding | Mid-Frequency Direct Current Welders

FASTER WELD RESPONSE: MFDC inverter systems operate at significantly higher switching frequencies than conventional line-frequency AC systems, allowing precise and rapid control of weld current.

WELD QUALITY: MFDC welding offers stronger, more reliable welds. The increased speed of MFDC welding produces fewer deformities in the metal being joined. Additionally, by making welds more quickly, MFDC welders reduce deformation and burn-through caused by prolonged heat affecting the area around the weld nugget. The result is a cleaner / stronger weld.

IMPROVED ENERGY EFFICIENCY: MFDC welding can reduce electrical demand and improve energy efficiency compared with conventional AC resistance welding, depending on the machine, material and welding application.

WELD CURRENT: Direct current systems utilizing SCRs have a rise time prior to their steady state. The MFDC is very responsive. It’s possible to create full-phase firing during the natural rise time to lessen the rise time.

WELD CONTROL: MFDC welders utilize IGBTs, for current switching. These units are turned on and off at a rate of 400-4000 times per second. By controlling this rate, the MFDC can very accurately determine the current.

MFDC (Medium-Frequency Direct Current) resistance welding is used when manufacturers need fast, precise, repeatable welds with better control of heat and current than conventional AC resistance welding.

MFDC is commonly used for spot welding and projection welding in applications such as automotive assemblies, sheet-metal fabrication, electrical components, appliances, wire products, and automated/robotic production.

Typical MFDC applications include:

• Automotive manufacturing — body panels, brackets, reinforcements, seat components, and other welded assemblies.
• Projection welding — weld nuts, weld bolts, studs, brackets, and multiple projections simultaneously.
• Thin or coated sheet metal — applications involving galvanized and other coated steels where precise heat control is important.
• Dissimilar or challenging materials — applications where tighter control of current and heat input improves weld consistency.
• High-speed production — short weld times make MFDC well suited to automated manufacturing.
• Robotic resistance welding — the smaller, lighter welding transformers commonly used with MFDC are advantageous for robotic weld guns.
• Multi-point welding — machines that make several resistance welds during a single production cycle.

MFDC equipment converts incoming AC power to a medium-frequency signal, commonly around 1,000 Hz, which is transformed and rectified into DC welding current. This gives the welding control much finer control over the weld current.

The main advantages are more consistent weld quality, faster current response, shorter weld times, reduced current variation, improved energy efficiency, and better control of difficult welding applications.

Yes. WSI offers standard and custom resistance welders equipped with MFDC inverter power supplies and controls, as well as TECNA MFDC resistance welding equipment.