Cold Metal Transfer (CMT) has spent 20 years redefining droplet detachment in welding. By reversing the filler wire at high frequency, the process slashes heat input by nearly a third and doubles welding speed versus conventional dip transfer. That cooler arc opened doors once closed to fusion welding—most notably the first thermal joining of galvanized steel to aluminum, a breakthrough that replaced solder or adhesive in many light-gauge assemblies.

The technology’s roots trace back to a modest fix for corroding light-bulb sockets at Osram. Early prototypes proved the concept of spatter-free ignition, but wire-drive inertia capped performance at ten forward-back strokes per second. Fronius engineers, led by Josef “Joe” Artelsmair, persisted: a gearless drive and precise current-wire-speed synchronisation eventually pushed CMT into production-grade territory, giving fabricators stable arcs on ultra-thin metals and making laser-like seams possible with MIG equipment.

Joe Artelsmair talks about developing welding machines for Osram.

CMT’s advantage is precise control: the gear-less drive snaps the wire back up to 70 times a second while the current momentarily drops to a few amps, so each droplet detaches at roughly 0.3 kJ/mm of arc energy. The ultra-cool transfer keeps thin sheet flat, leaves almost no spatter, and even fuses galvanized steel to aluminium without burning off zinc. Add-ons like CMT Pulse and CMT Twin lift deposition beyond 8 kg/h for heavier work yet keep the same tidy bead profile. Twenty years on, it’s still the benchmark for proving that smart control beats brute heat.

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