Offline presetting is part of a larger digital strategy, one that includes toolpath simulation software, a well-managed tool crib, predetermined work coordinates, and other manufacturing best practices. PHOTO courtesy Zoller
By Kip Hanson
I fell down a YouTube rabbit hole today. I wanted to confirm that what I’m about to tell you is still accurate, so I spent a few minutes looking at instructional videos for “setting tool lengths on a CNC machining centre.” A few videos in, I clicked on a well-known boxer turned machine shop owner teaching viewers manual programming techniques.
And I thought, “BOOM! No cutter compensation? What’s up with that?” I watched the thing three times and there wasn’t a G41 or G42 to be seen. I respect the guy, but this is basic stuff, and any programmer (especially a manual one) should know cutter comp. Maybe it’s covered in the advanced series?
Regardless, my journey down the rabbit hole verified that people still take the “sliding paper” approach to tool length measurement. Some use a 1-2-3 block, others a piece of shim stock, while a few have spent the money on one of those nifty LED-equipped electronic tool setters. At a minute or so per tool, however, all of them are wasting time.
Worse, all of them are taking a big chance. As with manual programming, setting tool lengths the old-fashioned way is asking for trouble; a single fat-fingered digit, a mismatched H-code, or forgetting to clear a wear offset—each of these can make for a very bad day.
I know many of you are skilled at this most fundamental aspect of CNC machine tool operation. But ask yourself this: setting aside the mistakes just mentioned, have you ever cranked the handwheel just a bit too far and chipped out a very expensive carbide end mill? And how about the newbies in the shop? Do you trust these well-meaning rookies to set tool lengths and diameters on their own, or is this routine task relegated to the more experienced and expensive setup people?
In the April 2022 edition of this magazine, I made the case for machine-mounted probing systems, which eliminate the paper and shim stock methods of tool setting. I stand behind those words, but I also stated that my imaginary production floor “would have offline tool presetters scattered throughout the shop, but that’s a story for another day.”
That day has arrived. Offline presetting is part of a larger digital strategy, one that includes toolpath simulation software, a well-managed tool crib, predetermined work coordinates (via zero-point workholding), and other manufacturing best practices.
In this most modern of machine shops, Shigeo Shingo’s five-decades-old SMED concept (single-minute exchange of dies) is a reality. Setups, even on virgin jobs, require only enough time to swap out the fixture, upload the program, and push cycle start. The first part is a good part and OEE is always in the high nineties. And there’s never a crash.
Sound like a fantasy? I’ve spoken with shops that do it every day. And the first step down this glorious road—one in which low-labour cost countries can’t compete—begins with offline tool presetting.
So do your shop a favor. Call the folks at Haimer, Zoller, Speroni, Dorian, Koma Precision…the list goes on. Drop $10K on a basic presetter, figure out how it fits into your process flow, document the results, and put it to work. Once you see your OEE improve, move that unit to the shop floor and buy a higher-end presetter for the tool crib. It’s the lowest-hanging fruit imaginable. SMT
TECHNICAL EDITOR KIP HANSON has more than 40 years experience in the manufacturing industry. He is the author of Machining for Dummies and Fabricating for Dummies and has written over 1500 articles on a diverse range of metal manufacturing topics.
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