Trumpf Inc. (www.us.trumpf.com) said its laser specialists have welded copper sheet metal to a depth of 0.020 in. (5 mm) in a one-time experimental setup.

Trumpf said its specialists welded the copper sheet with a combination of disk lasers of varying power. The company said no one was able to do this before because, as a highly reflective material, copper is difficult to weld, and, in most cases, undesirable side effects occur, including blowholes in the weld seams.

Trumpf said its specialists connected three disk lasers with 4 kW, 6 kW and 8 kW laser output, using a special fiber coupler in the application lab. More than 16.5 kW were brought onto the workpiece, resulting in a 5.9 ft./min. (1.8 m/min) welding speed that stabilized the dynamic melt pool common to copper.

The sheets, each measuring 0.118 in. (3 mm) in thickness, were welded together 0.020 in. (5 mm) deep with an overlap joint that had excellent seam quality, says Trumpf.

Trumpf said welding the copper required that the lasers be closely synchronized. The company said it believes the process could be placed into production for high volume parts but that the success of the application would depend on the welding speed and focus geometry.