Fast and flexible - EMO, machine tool show

This year's EMO - he premier European machine tool show - saw that continent's builders once again focused on innovative, but practical, product development.

When EMO was last held in Hannover, Germany, four years ago, the show was in a word, depressing. The mighty German machine tool industry, as well as the rest of Europe, was mired in the worst slump in a generation. And the news from this normally technologically elite exhibition had more to do with corporate realignments and cost reduction than with anything else, as so many European companies were moving into a survival mode reminiscent of the American machine tool industry of the mid 1980s.

This time around, however, the story was very different. While the general European economy is still in recession, conditions are far better for the machine tool builders. For one thing, the builders as a group are on stronger financial footing, having cut much of the fat out of their organizations and having established more viable business alignments - we'd call them mergers and acquisitions - where individual companies were in serious trouble going it alone. And equally important, European manufacturing in general is stepping up its investment again, cognizant of the need to cut costs through the development of more efficient production processes.

This situation, thankfully, has many European machine tool builders returning to more aggressive product development strategies of their own. While, like usual, many builders are pursuing a range of approaches to solving the manufacturing puzzle, there were some strong themes that played consistently throughout the halls of EMO. Most apparent were the notions of achieving greater speed and flexibility. By speed, we mean machines that move faster both in and out of the cut. And by flexibility, we mean machines that set up faster or otherwise move more deftly from one workpiece to the next. Here are some of the ways those ideas were on display at EMO.

Simply Fast

Perhaps the most striking presence at EMO is how commonplace high speed machining has become. Most of the leading European machining center builders had high speed models on display, and not just machines with fast spindles, but with significant other machine features that support accurate contouring at high feed rates as well.

High speed spindle makers are looking both to push the speed-and-power combination higher and to make their designs more dependable. Urged on largely by the aerospace industry, some builders are actively pursuing the technological goal of building a 100/100 (100,000 rpm/100 kW) spindle. But more are focused on addressing some lingering practical concerns in the 20,000 to 40,000 rpm range, which is growing common. Once such concern is service life. Currently a good life for a high speed spindle is 3,000 to 6,000 hours. That translates to just about two years.

High speed spindle failure is generally not catastrophic, says Siegfried Weiss, president of the German high speed spindle builder Weiss GmbH (Dyna Drive, Inc., Mentor, Ohio). "We've found that spindles are subjected to numerous little wrecks that over time that add up to a failure." According to Bill Popoli, president of the U.S. arm of Swiss spindle maker Ibag (Milford, Connecticut), there is a need for shops to understand that high speed spindles are not as "tough" as spindles found on standard machine tools. Still, it is a goal for Ibag and other spindle builders to get average service life up to five years.

As for control capabilities, it seems like the whole industry has upgraded to high speed CNCs capable of executing extraordinarily accurate cutter paths at very high feed rates - an enabling technology that has machining centers cutting everything from hardened tool steels (as hard as 62 Rc) to cast iron and aluminum auto and aerospace parts. For die/ mold machining, the newest capability now in the spotlight is curve interpolation, which a number of machine tool builders were touting - mainly those with Siemens and GE Fanuc controls. This feature allows complex curves such as non-uniform rational B-splines (NURBS) to be imported directly into the CNC rather than having to approximate those curves with point-to-point moves as is done in conventional contouring. The CNC interpolator then references the true curve math to contour more accurately, smoothly and, by most accounts, much faster too.

However, not everyone believes that curve interpolation is yet the total answer for high performance contouring. German control builder Heidenhain, Schaumburg, Illinois, for instance, thinks that curve interpolation makes sense only where data points in a conventional part program are clustered too close together to maintain a desirable feed rate. The far larger issue, they contend, is to apply look-ahead capabilities for the sake of real time "jerk control" - that is, to soften abrupt moments of axis acceleration and deceleration in order to create a smoother execution of conventional point-to-point contouring cuts. And that is a feature the builder was emphasizing, though they have introduced a curve interpolator as well.