A test I did with hardmilling...(long and boring)

Toolholder test. Heat shrink vs collet vs squeeze fit. All toolholders are the same length from the flange, all cat 40, all top of the line. Test was done on a 20,000
relatively new makino.
Using new cutters, all top quality brands, cutting multiple identical parts, I feel my results are conclusive.
Conclusion:
COLLETS........ I'm using lyndex, bearing collets made for high speed milling. It's said collets are good for roughing, because they absorb shock. Well the truth is they DO absorb shock. Problem is they cut like shit so who cares. When I roughed with the collets the tools did not chip, not even on flat floors. However, the cutters were definetely worn down rather quickly. Running a program with a constant feedrate, the collets were ran at 60% feed, as opposed to 160% feed for the shrink it and pressure fit. At 100% feedrate I thought the machine was going to blow up with the collets. For finishing...Collets SUCK. I'm trying to hold things to -.0002/side, and I have this unpredictable cutter diameter adding another tenth or two when it feels like it to my part. At high rpm, it's nice to have runout of a tenth or less, and thats asking a lot of collets. Not to mention you have this big fat area to hold smaller cutters with. Collets suck for tool holder clearance.
I give collets an F for hardmilling. I use one for my 40$ cmm probe, the rest collect dust.
Pressure fit.......
I'm using a trimos system. Very popular. Extremely fast and easy to load cutters. To date Iv'e had no cutters push up or spin. Isn't as rigid as the heat shrink, but close. Seems just enough to rough with. When roughing with heat shrink, cutters chip easy, there's no give when a chip gets back in the cut. The pressure fit has some give. The pressure fit has awesome tir, as good as the shrink fit, so it finishes at high speed well. The pressure fit seems to need a long shank to be rigid. It makes a difference if your shank bottoms out, not so much with the heat shrink. One downfall of pressure squeeze, the toolholder diameter is large, the larger the more rigid. Toolholder clearance sucks. Doesn't seem to be much difference between 2 and 4 etc... flutes as opposed to heat shrink. You can feel two flutes in the floor using heat shrink.
Heat shrink........
I hate loading them in. It takes too long. That aside, they are awesome for semi finishing and finishing. There is NO runout. Cutters cut exactly what they should to the tenth. No deflection in corners. If you go back and recut something in pressure squeeze, corners will hit a tenth or 2, but not with heat shrink. The holder clearance is awesome. Heat shrink seems to work best with multi flute mills at higher rpms. Very good with cutting the bottom of a 2 flute, much better than pressure squeeze or collets. Due to holder clearance, getting an air blast where you need it is a lot easier with heat shrink. Tools chip, but last longer as far as wear goes.
So now I rough with trimos cutters over .2, and rough with heat shrink under .2. I try to do all my finishing with shrink fit.
(this test was conducted with Cimitron. This software gets an A+ for constant chip load. There are no surprises.)
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Looks like you have all the "right stuff" - tools - to get the job done efficiently. Sounds like the shop management has made the correct decisions in equip t. choices. Just my opinion............but a Mold shop,with Cimatron, new Makino's with good tooling, milling within tenths!, are you in mold shop heaven? BTW its CIM A TRON <g>
& Thx for actually posting CNC related info!
-- ~g~
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wrote:

Looks like you have all the "right stuff" - tools - to get the job done efficiently. Sounds like the shop management has made the correct decisions in equip t. choices. Just my opinion............but a Mold shop,with Cimatron, new Makino's with good tooling, milling within tenths!, are you in mold shop heaven?
******** Thursday is gormet donut day. Most saturdays and a good bunch of fridays the owner buys lunch/breakfast. Foose ball table for breaks, Huge speakers all over, and get this...you can't be late. You start the minute you clock in, and stop the minute you clock out. I get there right a 7:12 each day, it's the right time for the traffic, i found a window that gives me exclusive use of the road. :)
I'd rather be fishing at a lake up in the mountains with a beer cooler with ice under my feet...but as far as jobs go this one is pretty cool. Enjoy it while it lasts, that's my motto.
Happy dount day to all!
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Thanks for posting something actually machining related. Now I gotta go look at shrink fit stuff!!
"D"
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