Statistical process control (SPC) requires collecting and analyzing data in real-time during production. Data integrity was a problem for Tier One automotive glass supplier, Guardian Industries (Auburn, IN), which supplies glass to clients such as DaimlerChrysler and GM.

According to Randy Miller, data systems technician for Guardian, gage er-rors and gage "fliers," in which gage readings fall outside reasonable boundaries, were part of the problem, as well as typographical errors made by operators entering data into the system.

Guardian collects data automatically from fixture gages and handheld gages, as well as through manual entry by operators using spreadsheets. For the past two years, the company has been using Kurt SPC for Windows developed by Kurt Manufacturing (Blaine, MN). Prior to the Windows version, Guardian had been using Kurt SPC for DOS.

While the DOS system was meeting Guardian's needs, it was not as flexible as the current Windows-based software, and its "clunky" DOS-type interface made the system more difficult for operators to use, Miller says. "Kurt did a heck of a job designing their DOS program, but there are barriers there," he says. "I was able to set up gage reading limits in the DOS system, but it didn't totally eliminate the gage errors. The Windows system is so much more powerful."

The Windows version is a 32-bit application that uses a high-level programming language that is similar to Visual Basic, enabling significant customization. "The software opened up a lot more programming opportunity," says Miller. "I can write codes inside the software that will virtually eliminate any type of gage or typographical error." It also gives the operator more feedback, he adds.

According to Miller, the graphical interface on the Windows-based system can be customized so that operators are more aware of what they are putting into the system. Some of the systems are programmed with a picture of the gage on the part so operators know right away the areas of the glass that are being measured, a feature that helps eliminate errors.

Miller says the software has reduced gage errors. "I did a one-to-one comparison on the same product using the new system versus the old system, and I found a 15% reduction in gage fliers," he observes. Beside gage error reduction, gaging is twice as fast. In other words, if it took a minute before to gage a windshield, now it would take 30 seconds. Part of the reason for this, Miller thinks, is due to the graphical interface. He is now putting in "traffic signals" for good and bad parts. "If there is a bad part, a red signal pops up and tells the operator it is a bad part. If it is a good part, a green signal pops up," he says.

Miller adds that the system has allowed operators to interface with a certain type of digital probe from Solartron Metrology (West Sussex, England). "Because we can interface with this robust probe using the new system, we are able to reduce gage fliers a lot more," he says. "We don't have to plug a wire into the gage. Instead, the probe is connected to the computer with one RS-232 wire."

-Kimberly Schmidt

Kurt Manufacturing
(800) 343-9884