High Speed Machining Precision Tooling - Indobiz.biz
High Speed Machining Precision Tooling - Indobiz.biz
High Speed Machining Precision Tooling - Indobiz.biz
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the part process and often<br />
present challenges. Also, deep<br />
cavities such as large door panel or<br />
bumper molds require deep reach<br />
with extreme clearances.<br />
• Cleanliness of the toolholder to<br />
avoid excessive run-out, especially<br />
when machining graphite.<br />
• Extending cutting tool life since<br />
high-end cutting tools are needed<br />
to obtain the best performance in<br />
the shortest time possible. These<br />
cutting tools often have exotic<br />
coatings that lend to an expensive<br />
price.<br />
• Finish. <strong>High</strong>er speeds and feeds<br />
are used with lower depth-ofcuts,<br />
which translates into<br />
better surface fi nishes. This<br />
makes balance even<br />
more important to minimize<br />
vibration at the cutting edge of the<br />
cutting tool. Also, proper chip<br />
evacuation provides better fi nishes.<br />
Based on these additional requirements,<br />
most mold shops have found that<br />
due to some inherent benefi ts, shrink<br />
fi t toolholders give them the best<br />
opportunity to accomplish the job<br />
competitively and accurately. Also, the<br />
evolution of inductive shrink fi t machines<br />
has made the shrinking process easier,<br />
quicker, safer and less costly to invest in<br />
this technology up front.<br />
Shrink Fit Advantages<br />
There are 10 inherent benefi ts that a<br />
good shrink fi t chuck can offer a mold<br />
shop:<br />
1. Unsurpassed accuracy<br />
A properly produced shrink fi t chuck<br />
should be able to guarantee 0.00012”<br />
(3 microns) maximum run-out at<br />
three times the cutting tool diameter.<br />
This accuracy is very repeatable from<br />
operator to operator.<br />
2. Availability of slim profiles<br />
Shrink fi t chucks are available with<br />
three-degree draft angles and<br />
very slim profi les. They can also be<br />
modifi ed to be straight walled if<br />
needed in order to prevent toolholder<br />
collision with the workpiece.<br />
3. Gripping torque<br />
A shrink fi t chuck grips the cutting tool<br />
360 degrees around the shank. This<br />
leads to a very high gripping torque<br />
that prevents the cutting tool from<br />
moving during roughing or fi nishing<br />
operations. This greatly aids in the<br />
reduction of scrapped parts.<br />
4. Extended reach options<br />
Shrink fi t chucks can use shrink fi t<br />
extensions that provide the user with<br />
many options with standard products.<br />
When machining deep cavities, one<br />
can place shrink fi t extensions into<br />
standard shrink fi t chucks, getting<br />
unsurpassed toolholder lengths with<br />
very little run-out.<br />
5. Balance repeatability<br />
and balanceable options<br />
Shrink fi t chucks offer the best<br />
balance repeatability of any<br />
toolholding system on the market<br />
since there are no moving parts. In<br />
many cases, if a shop purchases a<br />
properly balanced shrink fi t chuck<br />
with correct accessories (such as<br />
pull-studs) and uses good cutting<br />
tools without inherent unbalance<br />
(such as fl ats) then they can often<br />
have good balance characteristics<br />
for running at high speeds without<br />
doing an additional fi ne-tune<br />
balancing. Of course, if there is a<br />
need for additional balancing of the<br />
toolholder on a balancing machine<br />
after the assembly of the toolholder<br />
setup (toolholder plus cutting tool,<br />
plus pull-stud or coolant tube) then<br />
many shrink fi t chucks on the market<br />
come with simple to use balanceable<br />
options already built into the chucks.<br />
6. Reduction of toolchanging time/<br />
less toolholder accessory<br />
inventory<br />
Nothing beats the tool change time<br />
of shrink fi t chucks if the process<br />
is joined with a capable inductive<br />
shrink fi t machine. Tool changes can<br />
be done in fi ve to 10 seconds, and<br />
most importantly, consistently. This<br />
allows the toolholder assembly to be<br />
in the machine making chips more<br />
of the time, than out of the machine<br />
waiting to be changed. Also, a shop<br />
needs very little additional toolholder<br />
accessory inventory (i.e., collets,<br />
nuts, seal disks, etc.). This simplifi es<br />
the process.<br />
7. Cleanliness of setup<br />
A shrink fi t chuck typically is a sealed<br />
system by design. Therefore, the<br />
introduction of contaminants in the<br />
bore are minimized (such as graphite<br />
dust or chips). If contaminants are<br />
introduced to the bore of a toolholder,<br />
oftentimes run-out accuracy is<br />
compromised.<br />
8. Coolant options<br />
Shrink fi t chucks often have clever<br />
methods to deliver coolant or air/<br />
indometalworking news Vol. 2 / 2008 23
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