Flexibility Is Key to Automated Welding

Change in I/O and Control Architecture Supports Drive for Versatile, Flexible Welding Machinery

By Larry Koscielski

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The one sure thing that a machine builder faces is the knowledge that today's machines won't be good enough tomorrow. The face of manufacturing changed from a long-run, infrequent-changeover, inflexible production scheme to one that demands machines that can produce high-quality products safely with the versatility and ease of use required to change over and make other products quickly and accurately.

The machine builder that doesn't think about its future machine designs in that fashion might not be around long enough to have a next-generation machine.

CenterLine Limited in Windsor, Ontario, is determined to be around for a long time. We are a Canadian-based, privately held company that specializes in advanced automation processes and technologies that satisfy resistance-welding, metal-forming and cold-spray application needs.

The company is vertically integrated with products ranging from consumables to fully automated production systems. Main customers include original equipment manufacturers and tier suppliers in automotive, mass transit, aerospace and defense.

CenterLine is established internationally with manufacturing and service support facilities currently located in the United States, Mexico, Brazil, Germany, Romania, India and China. These operations help support CenterLine's customer operations internationally.

Challenging Customer Demands

In the process of updating our popular FlexFast welding machines (Figure 1), our company identified several requirements for increased flexibility and performance. Because the FlexFast's unique modular design is used for applications ranging from advanced fastener (nut & stud) welding to other resistance-welding applications, the versatility of the equipment needed to be supported by a controls architecture that was just as flexible.

In operation, a programmable servo axis moves the fixture that holds the part or parts in place to an operating area where a similarly programmed motion profile places the parts (nuts, studs) to be welded in position, and moves the welding electrodes in place to execute the welds based on the programmed "recipe" in the controlling PLC.

The design update was required to satisfy an expanding, globally competitive market, and to meet the demands of a growing customer base. To extend the flexibility of the machine, CenterLine needed an I/O and controls design that provided a common platform, allowed for a growing variety of tooling, and enabled its machines to interface with many different controller brands regardless of customer specifications.

"We were looking for a globally available platform that would be fast, flexible and provide the features that would satisfy the needs of our international customers," says Simon Britton, controls technologist at CenterLine. "When we evaluated various solutions, we decided to move away from DeviceNet and considered an Ethernet/IO-Link solution.

IO-Link allowed us to standardize many tooling fixture elements and run manufacturing in batches, resulting in improved modularity of the overall platform at an improved cost and faster turnaround time.

Controls manager Scott Pittl says that DeviceNet didn't give the Flexfast the update speeds it needed. "There's a lot of analog information, such as VeriFast electrode information that measures the position of the welding pin and the position of the upper electrode, passing through the network from devices," he explains. "All of this is needed quickly and precisely to make a ‘weld proceed' and ‘weld complete' decision."

Unique ID Manages Fixtures

A main hurdle with Ethernet was how to handle the analog signals effectively. IO-Link was a solution that had the proper signal resolution we were seeking, as well as being very competitively priced and accepted internationally. That particular value proposition made it easy for us to select IO-Link.

The new FlexFast design also demanded a controls architecture that could easily integrate new automation components with minimal concern. "The need to integrate new components on the machine quickly and easily is critical to addressing ongoing changes in production needs that this equipment is expected to satisfy," Britton adds. "For example, one challenge was that standard mechanical components and custom controls affect how the tooling fixture that holds the part is configured (Figure 2). IO-Link allowed us to standardize many tooling fixture elements and run manufacturing in batches, which resulted in improving the modularity of the overall platform at an improved cost and faster turnaround time."

IO-Link gives us the possibility to assign a unique engineering ID number to each fixture. With IO-Link, we can call it that number, and even with multiples of the same fixture, we can identify them individually with a memory-accessed node address on the fixture. We couldn't do that with DeviceNet.

To realize these objectives, CenterLine partnered with Balluff, a global sensor, networking and RFID component supplier. This enabled CenterLine to use a distributed modular I/O solution that incorporates IO-Link technology. IO-Link is a universal, vendor-neutral standard designed to make it easy to integrate automation components into any control architecture. 

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