View Full Version : Shrink fit tool holders

Dan B
12-16-2003, 01:59 PM
Does anyone work with heat shrink tool holders? Is this the preferred method for speeds above 12,000 RPM?

Any insight would be appreciated.



12-16-2003, 03:07 PM
Yes, they are the best...

This technology is getting cheaper too, competition is bringing the prices down, every one of the holder suppliers is offering their own.

We use this unit:

works great!
increased feeds by 30%
increased tool life by 70%

Carbide only though, so if someone puts say an Inserted End Mill holder in one of these, you won't get it out easily.
All is not lost though, you can pressurize the cavity between the tool and the retension knob by filling it with oil, then heat it up. Messy though...

You should check out the shrink fit stuff by Iscar...
cheaper yet and modular...


Dan B
12-16-2003, 03:24 PM
Thanks Scott.


12-16-2003, 07:02 PM
I feel pretty strongly that the Haimer shrink units are potentially best because of the computerized cycle time for inductive heating and because of their refrigerated cooling. Total cycle to heat and cool to room temperature is about a minute and a half to two minutes. I was recently in a shop that bought a cheaper inductive unit and it overheated the holders, distorted the taper, and left the holders on the bench to cool over 20 minutes. The long cycle time makes it more costly to use by wasting time. The potential damage to holders also increases operating cost. In addition, I have a safety issue with hot holders setting out.

12-16-2003, 07:13 PM
An afterthought to my last post...

Scot is absolutely right about increased tool life and performance gains. Accuracy and finish also improve a lot.

The potential economy of the modular systems is interesting, but for optimal performance when practical, I think a direct shrink fit in one-piece holder is best to minimize inaccuracy and to maximize rigidity. Modular is good, but one-piece still seems optimal to me.

The Haimer shrink machine has one other worthwhile feature. It's programmable heating allows use with the OSG and Teknara holders made by MST. Their stainless steel alloy seems troublesome for other inductive units. That flexibility for all makes of holders helps make it a sound investment.

12-16-2003, 07:23 PM

How is the price of the Haimer system, Is there a website?
Can they do HSS tools?

One other really nice thing about shrink fit:
No set screws! No flats to grind on the shank of a tool.
And as long as the diameter of the shank is the right size (I've never found one u/s) these shrunk fit holders will never let go of your tool, never...

Not with the 360 degree clamping force they exert...


12-16-2003, 07:43 PM

The Haimer system is a bit pricey at $12,000, but I know several using it and they all love it; no regrets. It's a one-shot investment that you can buy and use with pleasure. It will change your taste in workholding.

Yes, it will do high speed.

The factory in Germany is www.haimer.com. The USA operation is located here in Addison Illinois and their site is www.haimer-usa.com.

Their holder prices are quite good and once in use, you won't mind having paid the price for the shrinker.

Dan B
12-16-2003, 10:19 PM
It is the Haimer unit that we are looking at. We were quoted a price of $12,500, which sounds about right.

I was impressed with the refrigerant cooling system. After about 90 seconds, the tool and holder were back to room temperature.


12-17-2003, 01:54 AM
Dan B,
It's the first time i hear of heat shrink toolholders....hmmm interesting!
Tell me more, as i am a novice on this concept...


12-17-2003, 10:09 PM
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Hi Klox,

First, they made a batch of toolholders that came out of the grinder with the hole too small. Then, some wise guy decided, if he built an induction coil to heat the thing up, it would expand enough that he could quickly shove the cold endmill in it. Voila, a new product. Then, they proceeded to sell these second grade toolholders as if they were something new and exciting. Phooey, and they charge you extra for the goof-up. :D

12-17-2003, 10:20 PM

do i hear you right, you are not a believer in the advantages of shrink fit holders?


12-18-2003, 02:01 AM
Don't mean to rain on anyone's parade, Folks this is a vary old method of fitting parts togather. I first became aware of this method durning my days in aero-space maching, putting helocopter short shafts togather. If you don't want to spend a ton of money and just have a little fun, Get a blank tool holder bore it under size to the tool you want to mount (you have to play with going under size here). Think this out now, our goal temp is 50 to 60 below 0 dec f. We can get to that and below with dry ice or for those of you who have access to a bottle of nitrogen,regulator, some plumbing, a container like and old ice chest you are there. "Don't forget some heavy gloves". And did I say have Fun?

12-18-2003, 03:54 AM
LOL (X10)!!
Thanx Hu, you have brighten up my day! One more question: Can the holder be used more then once? (when the shivering endmill breaks, LOL!)


Dan B
12-18-2003, 06:43 AM
Hi Klox,

The holders apparently can be heated and re-heated up to 5,000 times before the bore starts to elongate.

As for the concept, I agree that it is not new. We used to shrink mold inserts with dry ice 25 years ago. In fact heat and cold have been expanding and contracting things since the beginning of time. Nothing new about the concept. However, being able to expand the holder in 3 seconds, place the tool, then cool it in a minute or two seems pretty time efficient to me. I've seen them in operation on the Hermle machine, and it seems like a good idea.


What would you recommend as an alternative to heat shrink, for high speed machining?


12-18-2003, 08:42 AM
the advantage of this type of holder would be (i presume?): to hold the cutter "better", prevent cutter to chatter and keep it from coming loose at high spindle speeds.....


Dan B
12-18-2003, 09:02 AM
Also, to eliminate runout. The shrink fit tools we checked on the Hermle were running out less than .0001" at the cutter tip.


12-18-2003, 10:01 AM
Hi guys,

No, I think heat shrink toolholders are a good idea. I'd use them if I had need for them. I was just speculating on how the first instance came to be :)

I can imagine these are easy to assemble, not so easy to remove? The smaller the shank, the tougher it is to gain the expansion differential for disassembly?

Dan B
12-18-2003, 12:20 PM
Hi HuFlungDung,

From my observations, they disassemble just as easily as they assemble. They had no problems removing a 3 mm ballnose cutter. Just make sure you grab the tool with a welders glove on, or you will get seriously burned.


12-18-2003, 08:54 PM

i'm like a reformed smoker on this topic. i thought "who the hell wants a hot holder around? too unsafe and too long. Then a tool salesman said what's wrong with you? you get 4 times cutter life! Then i met Haimer and saw under 2 minutes to heat, unload, load and cool. That made it fast and safe. The tool life improved as described, but better, the deedrate, finish, and accuracy improved too. I'm German and I lived in Missouri (briefly), so i had to see it. Today i'm convinced! Simple physics says heat shrink is really cool!

12-18-2003, 08:58 PM
sorry, i missed the close quote after "around?" and misspelled feedrate as deedrate. apologies! long day!

12-19-2003, 09:12 AM
Are these improved tool life and cutting speed numbers for machining steel?, aluminum?, wood?

Dan B
12-19-2003, 09:26 AM
You will see improved tool life when cutting hardened steel, for sure. It's amazing what they can cut with these HS machines. I've seen examples of 1mm ballnose cutters producing very narrow grooves an inch deep in tool steel pre-hardened to 62 Rc !! Although this isn't something we would ever do, it is still impressive to see it done.

As for wood, I don't imagine there would be much difference, although I could be wrong. I don't work with wood.


12-19-2003, 09:36 AM
Shrink fit and balanced tool holders are normally used in HSM due to the high revs involved (sometime up to 40,000 or even more) and for machining hardened steel and graphite electrodes. The feed used are extremly high, rapid feedrates of a normal milling are used to machine the material involved.

01-01-2004, 07:57 PM
For some time now, I'm using my "own Version" of shrink fit!
When buying Endmills in HSS, I usually buy Kennametal, because anything smaller than 3/8 " they come with a larger shank, but not so, with Carbide Endmills.
I had to mill 1/8 ball nose groves into 4140 H.[Tear trimm on rubbermolds] and I found they don't last very long, too much
flex in your collets.....it would be nice, if they would make short stubby ones with 3/8 shank,
you don't need a standard length, if you only have to go 1/16 deep!

So what I did was, I made a few 1/2" diam.solid collets, accurately drilled a 1/8 hole into it,
cross drilled a 1/16 diam. hole a the bottom of the hole [for air escape] then silversoldered the
1/8 coated ballnose into it, so about half of the length of the flute is also soldered.
It made a world of a difference, about 300% increase in toollife.

And it's not really a big deal to change it, 5 to 10 min.
I must admit, It might not be for everyone, if you have not allot of soldering experiences, it could fail.
We manufacture a fair number of special hole saws, like muellercutters, [ for hot taping ] in HSS, and Carbide, anywhere from 1/2" to 14" in diam.,so soldering is not a problem.

Does any of you have the same problem, or have you found a source on special carbide cutters??


02-15-2004, 08:03 PM
Hi, my name is Randy. Shrink fit is awesome. Been using it since 1998 for HSM'ing. See this site for information, Shrink Fit, Tool Holder Balance and Tooth Pass Frequency.



02-28-2004, 05:58 AM
See this site, it has an article on Pieces of the Puzzle - Shrink Fit that might explain the basics, Thanks.


03-06-2004, 12:57 PM
As RPM increases, so does centrifugal force...

The clamping force of a set screw(s) in the case of a solid holder, and even the clamping force from a collet can be overcome by centrifugal force.

Small end mills have the smallest set screws and therefore the least amount of “clamping force” in a solid holder, yet these small diameter tools use the highest RPM and see the greatest centrifugal force.

Ever see an end mill or drill come out of it’s holder, or break at high RPM? That’s why we need to use bullet proof lexan in those doors… In fact, come to think of it, I’ll order some ¼” instead of the 3/16” thick lexan I have now. As the diameter of the tool or mass increases so does the centrifugal force acting on it, so we never want to see a tool bigger than ¼” diameter flying around inside our completely enclosed CNC machine right?

Some shrink fit holders offer coolant thru channels or even holes.
Having 10k spindles and low pressure (40 psi) through the tool coolant, I have not seen the effect of centrifugal force acting on the coolant coming out of the holder spinning off outward from the tool, thus leaving it dry.
But at 15k, centrifugal force begins to affect low pressure coolant flow.
At 20k, centrifugal force has a significant affect on any coolant flow coming out of a “rotating reference frame” see:


RPM’s above 20k you need to use coolant flow that is external to the rotating spindle…

The clamping force of shrink fit holders cannot be overcome by centrifugal force. Practical example: except, when the interferance fit of the tool is not sufficient, as in the case of an undersize tool shank, or a worn or oversize shrink fit holder...