There is no room for error in the production of these parts, both for safety reasons and because the parts are expensive. Some are worth $75,000 apiece, says Group 5 Engineering owner Rich Ushler. "If I make a mistake, I'd have to mortgage my house," he remarks.
Group 5 Engineering relies on a variety of German and Swiss machines to attain the high accuracy and reliability required, including milling machines from Bridgeport and Deckel and lathes produced by HES and Schaublin. Many of these machines are equipped with controls and digi-tal read out (DRO) systems from Heidenhain Corp. (Schaumburg, IL), which Ushler sees as a major key to their accuracy.
Compared to systems equipped with manual dials, the DRO systems allow for more precise control, he explains. "When you are dealing with such expensive parts, it is imperative to be certain where you are, and I am confident about my position with the Heidenhain feedback," Ushler says.
Ushler got his first experience with Heidenhain about 2 decades ago, when the company purchased a Bridegport machine that was equipped with a Heidenhain control. "It was accurate, reliable and easy to use even then," he says.
As a result, whenever Group 5 Engineering has a need to automate or increase the accuracy of a man-ual machine, it regularly turns to Heidenhain, which offers retrofit systems known as Retrokits for upgrades of mills and lathes.
The Retrokits typically consist of a two-axes DRO and two sealed glass optical linear scales that come complete with armor shielded cables, custom-designed brackets, and arm and tray assembly. The optical linear scales can vary depending on the ap-plication, but typically have a grating period of 20 microns, or 50 pulses per millimeter. The accuracy grade is + or - 10 microns with distance-coded reference marks. Each optical linear scale can be used in shop floor environments.
One of Group 5 Engineering's latest retrofits involved a lathe that was outfitted with Heidenhain's ND 730 DRO and LS 603 linear scales. "If these systems save me from making a single mistake, they've paid for themselves," says Ushler. "And they do." And besides the improved accuracy, there's often an added bonus: reduced cycle Arial. According to Ushler, some jobs can go 30% to 40% faster after machines are converted from manual dial controls to DRO-based systems.