DETROIT - An electrically driven robotic welding gun is being tested on Chrysler Corp.'s big pickup truck line.
Pneumatic welding guns are the prevailing technology on assembly lines today. But Nachi Robotic Systems Inc. of Novi, Mich., has other ideas.
Chris Miller, Nachi robotic applications engineer, said the programmable gun has been welding on rear window seams and rear cab areas of regular and extended-cab Dodge Dakota pickups built in Warren, Mich. It is being used along with existing welding equipment.
The electric drive offers precise control of the welding contacts, Miller says. Operating like a large crab claw, the gun rapidly makes a series of small precision welds along a length of metal. It clamps with 400 to 600 pounds of pressure. The strong clamping makes clean and small welds, and keeps components aligned.
Nachi's programming opens and closes the gun variably to clear complex shapes as the robot moves along the seam. Pneumatic welders, by contrast, require a full open-and-close cycle at each weld.
The welder also uses computer measuring to monitor its own performance. It can prompt line operators when welding contacts need replacement. It also can send an alert when one contact may be burning away faster than the other, indicating potential weld trouble. Miller said the monitoring reduces waste.
'Right now, on pneumatics, about every three hours they just close down the line and go through to change tips. They just go down the line and replace everything,' Miller said, noting that the practice shows potential for cost improvement.
The machine was shown at this month's International Automotive Manufacturing Conference & Exposition in Detroit.
Miller said the Chrysler test for the Nachi system is open-ended. 'We'll keep it there just as long as they let us.'