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Seeing Quality

Cameras and readable ID marks are helping manufacturers improve their products so that recalls can be minimized.

Did you know that your cellular phone is making it easier for automakers and suppliers to produce better quality products, while reducing warranty costs? As cell phones get smaller and more capable of operating at higher processing speeds, the advancements in processing power will make it easier for machine vision companies to turn that power into low-cost, reliable vision systems that can monitor component assembly, down to the most intricate detail. The approach is to deploy small, fixed vision cameras on automation devices so that the assemblies can be checked as they move down the line, thereby making part verification before the end of the line.

BMW's factory in Dingolfing, Germany, where the 5-, 6- and 7-Series, as well as the M5 and M6 are built, is using technology provided by ISRA VISION Systems AG (www.isravision.com) to verify whether the proper brake calipers have been installed on the appropriate vehicle by looking at the contour of the caliper. In addition to the identification process, the system also performs quality inspections to validate whether enough caulk has been used on the union nuts that attach the caliper to the shaft. If an abnormality is identified, the system sends a message to the central computer to broadcast an alert. This is especially important because of the number of models produced at the plant. "The more you mix things up, the chance to make a mistake is great," says John Merva, president of the Automated Imaging Association (www.machinevisiononline.org; Ann Arbor, MI). "Over time, the capabilities of these systems will dramatically increase and this technology will move to more of a commodity." 

Assuring that abnormalities don't get built into the major components in the first place is the task for a process called Direct Part Mark Identification (DPMI). This process requires that each part of an engine, for example, including the crankshaft, block and pistons, is marked with a 2D code, or mark, through various methods, including dot peening, laser, ink-jet and electro-chemical etch. That code—which can be applied to just about any surface, regardless of shape—is read by small machine vision readers to assure the correct parts are going into the correct engine. Ford recently completed a three-month test using 2D marking systems of some of its engine and transmission components. The systems can also assure the proper items are being delivered line side, which helps to further reduce potential errors.

The use of the 2D barcodes provide an added benefit in that data from each code can be stored in a mainframe and if a potential issue is identified that could cause a recall, the OE and supplier could easily identify which products have been impacted, down to the specific vehicle and customer, says Carl Gerst, director of ID product marketing at Cognex Corp. (www.cognex.com; Natick, MA). "They could narrow it down to the VIN by lot made within a certain week. When they start using full-line parts traceability, they can even get down to the exact vehicle," he says. "It could get to the point where they can place a call to each individual customer." This will allow OEMs to better target recalls without having to bring back thousand of vehicles, some of which may not have been affected at all. Another key benefit here is the value of protecting the image of the OE from the bad publicity that commonly results from a recall. The use of 2D barcoding also allows suppliers and OEMs to better orchestrate when a changed part needs to be installed. The new code can be identified by the vision system and cleared for install, while parts with the outdated barcode could be rejected by the delivery systems before they reach the assembly line.

The real benefit, Gerst says, is the use of the data to improve manufacturing efficiency. "When people first started to market the concept of full traceability they focused on warranty being the return on investment, but in reality the true ROI can be made within the four walls of the plant." The data can be used to project which transmission bell housings, cam shafts or engines are most in demand and adjust inventories at each plant accordingly, for example. "We've seen examples where manufacturers have taken a close look at the data and seen their inventory turns jump five times, resulting in as much as an $11 million drop in inventory in one case," Cognex's Gerst says. "In reality, the mark is becoming just as valuable as the part itself."