Page 20 - MetalForming July 2012
P. 20

Adaptive Resistance-Welding Control
 two- or three-times sheet thickness or the presence of adhesive in the joint. And, the control can sense changes to the process as the welding electrodes wear, making the appropriate weld- schedule adjustments to ensure good- quality welds.
“The Aro adjusts the three key process variables—current, time and force—in real time to generate pre- cisely the amount of heat needed for each weld,” says Gastmeier. “It can adapt for any condition that affects the resistance in a given weld joint.
“By eliminating all of the operator’s wasteful moves around the assembly,” continues Gastmeier, “and freeing him up from having to call up new weld schedules periodically, we reduced cycle time per wheel-housing assembly by 25 to 30 percent. That’s a huge sav- ings over the 300 assemblies we pro- duced, savings that we again passed along to the customer.”
PTM completed the wheel-housing job in January 2012, releasing com-
pleted assemblies to its customer in lots of 25 to 30.
In addition to making speedy work of each assembly’s 275 welds, the adap- tive control also makes fast work of the daily startup procedure the operator follows to verify that the welder is prop- erly functioning. Before bringing in the Aro system, this every-morning startup procedure entailed performing coupon tests of every variation of sheetmetal type and joint thickness that would be welded that day. That verification process consumed at least one hour every morning.
“With the Aro,” says Gastmeier, “the startup procedure has been reduced to just 5 min. We perform just two or three material stackup tests and we’re ready to go.”
A Common Gun Body
and Interchangeable Arms
Accompanying the adaptive control to PTM was a pair of new Aro Ergoflex welding guns. One control can manage
both guns and two operators simulta- neously—another time saver for the company. The Ergoflex design employs a central gun body to which the user can affix any of several available sets of arm styles and sizes. PTM uses guns with 30 in. of reach and a 20-in. jaw opening.
“I’ve been aware of the Aro adaptive system and flexible style of welding guns for a few years,” Gastmeier adds, “having seen it in use in other proto- type facilities and even in some OEM plants. I’ve always thought it would be a good fit for us, and landing that big wheel-housing program presented the perfect opportunity to make the invest- ment. Now, as we bring in more resist- ance-welding work for our newly upgraded cell, we’ll look to expand— additional arms, and perhaps another controller. I can definitely see the need for arms with longer reach and open- ing, for example, to enable us to take on larger assemblies and improve weld- joint access.” MF
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