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Posted by Ed Huntress on May 1, 2008, 11:10 pm
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>> I haven't followed this thread so excuse me if this has been covered, but
>> I
>> hope you know that the hard part with induction-heated heat-shrink
>> toolholders is not getting the tool in and clamping it, but getting the
>> tool
>> *out*. If you even slightly overheat the holder before you put the tool
>> in,
>> or if your induction heater is just a wee bit slow, you'll never get the
>> tool out. Sophisticated systems, like Bilz's ThermoGrip, involve a *lot*
>> of
>> timing experiments in the course of their development.
>
> I believe it. That was one of the things I was wondering about. How
> do you avoid induction heating of the endmill/tooling?
> Or, does the "gap"/interface between the tool and the holder decouple
> it enough to allow differential heating.
They avoid heating the tool by heating the holder so fast that heat doesn't
have a chance to conduct in to the tool shank. If it does, you're a dead
duck when you try to get the tool out.
The clamping results in a very tight interference fit, so conduction between
the holder and the tool is practically uninterrupted. You don't gain any
significant edge from the transition between toolholder and tool insulating
the two from each other. The bore of the tooholder is actually cool enough
to touch, as is the tool shank, at the instant the holder releases its grip.
Power is critical and the timing for applying the removal force is critical.
They work in seconds.
>
>> All of which is OK if you're planning on making a permanent
>> toolholder/tool
>> assembly. d8-)
>
> Well, I guess I'll try a drill chuck first :-) If all else fails,
> I've got a permanently mounted drill chuck on a BT40 shank :-)
>
> Thanks.
> -Ralph
Ha! Well, that would solve the problem.
I wrote quite a bit about these gadgets when they were first becoming
popular, and they are really great for the appropriate applications. But
"appropriate applications" are high-speed milling with some horsepower.
Unless you're spinning the tool at something over 10,000 or 15,000 rpm,
with, say, 10 or 20 horsepower, their advantages are not very great. Of
course, once you've invested in one of the things, it's worth using it for
your ordinary tooling and speeds, too, if you're running multiple machining
centers and you have a big inventory of tools. I've never heard of anyone
using shrink tooling with a drill chuck, but I guess it would be OK if you
also had your MC tooled with multicoated or ceramic inserts, running at the
max.
Otherwise, the conventional solutions are a lot less trouble and expense.
--
Ed Huntress
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Posted by Winston on May 1, 2008, 10:09 pm
Please log in for more thread options Ed Huntress wrote:
(...)
> All of which is OK if you're planning on making a permanent toolholder/tool
> assembly. d8-)
Thanks, Ed.
I was completely unaware of that.
--Winston
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Posted by on May 1, 2008, 10:57 pm
Please log in for more thread options On Thu, 1 May 2008 20:47:20 -0400, "Ed Huntress"
>All of which is OK if you're planning on making a permanent toolholder/tool
>assembly. d8-)
http://www.ameritherm.com/overview_shrinkfit.php
A lot of good free information available however to get the more
detailed technical data you be asked to fill out a form with your
contact information.
http://www.cihinduction.com/reheating.htm
Tom
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Posted by Ed Huntress on May 1, 2008, 11:16 pm
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> On Thu, 1 May 2008 20:47:20 -0400, "Ed Huntress"
>
>>All of which is OK if you're planning on making a permanent
>>toolholder/tool
>>assembly. d8-)
>
> http://www.ameritherm.com/overview_shrinkfit.php
>
> A lot of good free information available however to get the more
> detailed technical data you be asked to fill out a form with your
> contact information.
>
> http://www.cihinduction.com/reheating.htm
>
> Tom
That's good info for making a permanent shrink fit, but the trick with the
tooling application is getting the tool out of the holder when you want to
change tools. It's difficult.
I should point out that it's easy with carbide tool shanks, but very
difficult with steel, because of carbide's lower coefficient of thermal
expansion.
--
Ed Huntress
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Posted by on May 1, 2008, 11:38 pm
Please log in for more thread options On Thu, 1 May 2008 23:16:34 -0400, "Ed Huntress"
>
>> On Thu, 1 May 2008 20:47:20 -0400, "Ed Huntress"
>>
>>>All of which is OK if you're planning on making a permanent
>>>toolholder/tool
>>>assembly. d8-)
>>
>> http://www.ameritherm.com/overview_shrinkfit.php
>>
>> A lot of good free information available however to get the more
>> detailed technical data you be asked to fill out a form with your
>> contact information.
>>
>> http://www.cihinduction.com/reheating.htm
>>
>> Tom
>
>That's good info for making a permanent shrink fit, but the trick with the
>tooling application is getting the tool out of the holder when you want to
>change tools. It's difficult.
>
>I should point out that it's easy with carbide tool shanks, but very
>difficult with steel, because of carbide's lower coefficient of thermal
>expansion.
Not expecting the OP to use that page for his shrink fit, just passing
along a source for information.
They have a lot of free information, videos, technical data, theory,
application & How To's, including for this OP how to design coils, but
he will have to navigate the site to find them all.
Tom
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>> I
>> hope you know that the hard part with induction-heated heat-shrink
>> toolholders is not getting the tool in and clamping it, but getting the
>> tool
>> *out*. If you even slightly overheat the holder before you put the tool
>> in,
>> or if your induction heater is just a wee bit slow, you'll never get the
>> tool out. Sophisticated systems, like Bilz's ThermoGrip, involve a *lot*
>> of
>> timing experiments in the course of their development.