Swiss Machining Made Simpler
Swiss-style machine tools can be a good choice for making complex parts. On the downside, however, Swiss machining itself has a reputation of being complex—and, therefore, more difficult to master than standard machining.Get more news about
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That’s why companies that produce Swiss machines and related products have been trying to make Swiss machining simpler for operators, setup personnel and programmers. Their efforts have yielded a number of important advancements. In addition to taking advantage of these, shops interested in Swiss machining can take some practical steps to make it easier for operators to get a handle on the process.
Making a Swiss Switch
A Swiss-style lathe is a turning machine that feeds the stock through a guide bushing. The tool cuts the stock near the bushing, which is the support point, no matter how long the workpiece. This makes Swiss machining a good choice for long and slender turned parts, such as needles.
The guide bushing is what makes Swiss machining possible,” said Randy Carlisle, an applications engineer at Index Corp., Noblesville, Ind., a Swiss machine builder. According to Carlisle, the guide bushing arrangement allows machining of parts with length-to-diameter ratios as high as 50.
On the other hand, the guide bushing is “where 80 percent of your problems happen,” such as out-of-roundness and tool chatter, noted Chris Leclerc, Swiss product specialist at CNC Software Inc., Tolland, Conn., a CAD/CAM software developer.
So one approach to dealing with the difficulties of Swiss machining is to do less of it by using what Carlisle calls a convertible Swiss machine. This type of machine allows users to take out the guide bushing and move the chuck into its place. The “chucker mode” produces shorter parts with high accuracy in roundness, concentricity, and straightness, according to Leclerc.
Carlisle’s company and others are now turning out Swiss machines with a removable guide bushing. With the guide bushing out, “you’re back to normal lathe-type turning” of parts with maximum length-to-diameter ratios of only three, Carlisle said. “But if job shops have a mix of long and short parts, they can reinstall the guide bushing whenever they need to.” For Index machines, he added, it takes about 15 minutes to switch between Swiss and non-Swiss modes.Other simplifying Swiss advancements relate to tooling. Since they lack a tool touch probe, “the biggest complaint about Swiss machines is that there is no easy way to touch off tools,” said Derek Briggs, Swiss product manager for Tsugami/Rem Sales LLC, Windsor, Conn., which sells Swiss machines. But shops can make up for this by using an offline tool presetter. Tool presetters are measurement devices used to set up cutting tools before they are installed in the machine. Presetter advantages include shorter setup time and greater tool-setting accuracy.
Though not restricted to use with Swiss-type machines, tool presetters have become increasingly popular with Swiss machine users over the last couple of years, according to Ed Garber, national sales manager for Star CNC Machine Tool Corp., Roslyn Heights, N.Y., which makes Swiss-style automatic lathes.
“Now, most companies are looking to have tools show up qualified (preset) before a job gets set up,” Garber said. “That makes things simpler for the operator.”
Another fairly recent development on the Swiss scene is the emergence of quick-change tooling, Garber noted. The growing popularity of quick-change, a modular system featuring interchangeable cutting units, is easily explained: “Once a machine is set up and running and you have to change out a tool, you’re going to save a lot of time if you don’t have to re-touch the tool off,” Garber said.
To make Swiss machining easier, many customers of Tsugami/Rem Sales want to be able to preset tools outside the machine “and then pop one out and pop one in,” said Briggs. “So we have tried to find outside vendors that can make more of a quick-change type tool for our machines.”
As an example of this, Briggs cited cartridge-style gang plates. With one of these new gang plates, he explained, “you take the cartridge out [by loosening] one screw, change your insert, slide the cartridge back in and your tool is already touched off and you’re good to go.” This system, he said, significantly reduces the amount of time and operator intervention needed to get a machine back into production after work stops for a tool change.
