The Pulse Arc Welder
The Pulse Arc Welder
Generic name for the bench micro-welder that has reshaped jewellery repair
A pulse arc welder is a benchtop micro-welding system that joins precious metals by delivering short, high-energy electrical pulses through a tungsten electrode, fusing the metal at the weld point without solder, flux, or filler material. The technology is the generic equivalent of the proprietary Lampert PUK system that introduced the method to the international jewellery trade from the late 1990s onward. Pulse arc welders have become standard equipment in fine-jewellery workshops because the localised, brief heat input allows repairs and modifications near heat-sensitive Mogok ruby, Sri Lankan sapphire, Colombian emerald, opal, pearl, and other vulnerable gemstones in situ — work that previously required dis-assembly and re-setting around a torch.
How it works
The bench unit generates a programmable electrical pulse, the operator brings a tungsten electrode held in an insulated handpiece to a fraction of a millimetre above the work, and the resulting arc melts a small volume of metal directly beneath the electrode tip. Surface tension and rapid cooling fuse the metal into a small weld bead. Argon shielding gas delivered through the handpiece prevents oxidation. Pulse duration is in the millisecond range, and energy is selectable for different metals — yellow gold, white gold, platinum, palladium, sterling silver — and for the size and depth of weld required.
The thermal envelope of a pulse arc weld is small enough that a stone seated in a setting a few millimetres from the weld point typically experiences no significant temperature rise, though competent workshop practice still calls for the use of heat-shielding compounds on the most heat-sensitive material. The cosmetic finish of a pulse arc weld is usually clean enough to require only minimal subsequent polishing, particularly relative to the post-finishing required after a torch-soldered joint.
Common applications
Standard workshop applications include ring sizing without removing settings, repairing broken claws and prongs in pieces holding heat-sensitive Mogok ruby or Sri Lankan sapphire, reattaching bails and jump rings, building up worn metal at high-wear points, joining chains, and tack-welding fabricated components prior to final assembly. The technique is also used for repair of antique and period jewellery — Edwardian, Art Nouveau, Art Deco — where original solder joints can be fragile and original gemstones may have been treated using methods making them more vulnerable to thermal damage than modern equivalents.
Brands and market
The Lampert PUK from Werneck, Germany, is the dominant brand by global market share, to the extent that PUK is often used as the generic term. Other current suppliers include Orion (United States), Sisma (Italy), and a number of Asian manufacturers. Pricing for a current-generation pulse arc welder bench unit sits in the low to mid four-figure range, placing it within reach of independent jewellers and small workshops, in contrast to the laser welders that perform a comparable function at a price point typically four to ten times higher.
In the trade
For Skyjems and the broader fine-jewellery trade, the pulse arc welder is now a routine assumption rather than a luxury. A workshop without one cannot safely undertake the full range of bespoke and repair work expected of a private dealer handling pieces with valuable origin-disclosed gemstones. The technology, alongside laser welding, has effectively eliminated the previous category of repair refusal in which a piece with an irreplaceable stone could not be sized or repaired by torch. The system is documented in the trade workshop literature and in the jewellery-fabrication curricula at the major training institutions.