Shrink fit tool holders

Hey gang,
My company manufactures induction heaters. We've sold a number of
heaters to CNC shops that use shrink-fit tool holders in their CNC
machines. We supply the RF source and they make the jig to hold the
collet and tool. So I've never seen an actual collet.
I want to make a setup for my salesmen to demonstrate shrink-fit
tooling replacement.
Several questions.
What would be a typical interference fit between collet and tool?
Would it be cheaper to buy a collet and say, end mill than to have
something made?
What should I expect to pay for a collet (are there various sizes?)
and where would I look to source one.
Are the collets standardized across the industry or does each CNC tool
maker use a different design.
Anyone have a damaged, worn-out or otherwise unusable collet they'd
like to donate to a worthy cause? Shipping and handling gladly paid,
of course.
John DeArmond
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Tellico Plains, Occupied TN
See website for email address
Reply to
Neon John
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I'm going to tell you what little I know, and then someone who actually DOES know will come by and correct me.
1: I'm sure it'll be cheaper to buy the mills, but you may have to make (or have made) your own collets. The collets will be a precision turning inside and out -- the hole will need to be reamed, the outside ground.
I googled Shrink and Collet and got several pages, including this one:
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It looks like there's only one player at the moment, but I didn't spend much time.
2a: I don't know how much to pay. Judging from the page I found, lots.
2b: Yes, there are various sizes (and shapes), but it looks like there's one standard.
2c: I don't know where to source one, but now you have a company name.
3: See 2b for part of the answer. I honestly don't know if shrinkable collets are an industry standard -- try Google, and you may get many questions answered.
I'm guessing, but I suspect that what you want to do is to make a really nice video of someone using your machine to shrink a collet onto a tool. Personally, I'd call up one of the shops that does it and ask if I can show up with a camera and take up a few hours of their time -- there may be enough good will there that they'd take you up on it, particularly if you could afford to leave a spare machine behind when you left.
Reply to
Tim Wescott
Few of the people left actually do metalworking - the place has become a hallowed hall for the spewing of mostly right-wingnut political rants and lots of folks more interested in metalworking have packed up and left. On an average day 90+% of the posts die in my kill filter.
I do metalworking, a bit, but don't feel particularly qualified to answer your question, since the only shrink fits I have dealt with were bearings, and those few and far between. The only CNC tool I have uses collets, but it's a Porter-Cable 690 router with split collets, used on wood, not a metalworking tool at all (what might be the last vaguely operational cable-drive shop-bot on the planet - 19 years young. I begin to think it's time to chuck the ShopBot drive system with it's quaint DOS/Serial interface and see if one of the "3D-Printer oriented" arduino-based programs might be able to grok cutting rather than extruding, as getting the upgrades from ShopBot quickly became a treadmill of great expense I could not keep up with.)
Reply to
Greetings John, The tools are held in a tool holder, not a collet. A collet fits inside a collet holder of some sort and then a tool fits inside the collet. With thermal shrink fit tool holding a tool holder is used without a collet, the tool fits directly in the tool holder. The tool holder will have a taper for fitting into the machine spindle. I don't remember what the amount of interference is but it is quite small. Over time after many cycles of heating and cooling the I.D. of a particular tool holders will expand and so the holder starts losing its grip. Some shrink fit tool holders use special cutters that have a helical groove machined into the shank. This direction of the groove causes the tool to be drawn into the holder from cutting forces trying to cause the tool to spin in the holder. Your best bet is to look for a tool holder on eBay if you need to buy one. If you search for a "shrink fit tool holder" on Ebay you will see several new holders for less than $150.00. Since they start to lose their grip over time one of your customers may have one that they are no longer using. Even though the grip is too weak for machining it should be good enough for demo use. Cheers, Eric
Reply to
There are several shrink-fit systems. Generally, they use standard straight-shank cutters, but they have to be accurately sized.
I wrote several articles about Bilz's system years ago, but I don't remember a lot of details. I do remember that the cutters needed to have accurately-ground, straight shanks. And watch out if you're using HSS cutters: They're easy to insert in one of the thermal collets, but they can get really stuck and hard to get out, unless the heater expands the collet (holder) *really* fast. The more recent induction-type heat-shrinking systems typically handle HSS quite well, if you don't linger in pulling the cutter out of the holder.
If you want to get into it, call or check the websites for Bilz, Kennemetal, Techniks, etc.
Reply to
Ed Huntress
Most of the shrink fit tool holders will work with standard tooling. If you buy a Chinese cutter the shank may not be accurate enough. I have seen Chinese cutters with both over and under sized shanks. Like I said in my first post there are some shrink fit tool holders that take special shank cutters, but I think they are on the expensive end of the spectrum. Maybe one of your customers will have a dull cutter to give away too. Eric
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