ATS Systems Ultimate Chuck Installation and Operations Manual
chuck run and maintain 50% of it's static grip force of
19,000 lbs.?
Monoblok jaw weight = 1.5 lb./jaw = w
ju
Distance
from chuck centerline to center of gravity of jaw =
2.5" = r
c
n
max
=
19,000 - 9,500 x 188 =5465 rpm
1.5 x 2.5 x 3
Example 2:
Ultimate Chuck size 210 (8") with full size
monoblok soft jaw gripping 2" diameter.
What is the loss of grip force if the chuck is
run at 6000 rpm?
Grip force loss, total all three jaws:
= 1.5 x 3 x 2.5 x 6000 x 6000 = 11,507 lbs. loss.
35,196
or, if you started with a drawbar pull that yields
19,000 lbs. static you will have 19,000 minus
11,507 residual grip force remaining at 6000 RPM
(assuming the weights, measurements and all
other assumptions are accurate.) or about 7,493 lbs
= 39% of the initial 19,000 lbs.
Example 3:
Ultimate Chuck size 315 (12") with a full
monoblok soft jaw gripping a 3.5" diameter. How
fast can you run and maintain 50% of an initial
30,000 lbs. of grip force?
Jaw weighs 5.4 lbs., r
c
= 4.075"
nmax =
30,000 – 15,000 x 188 =
2833 rpm
5.4 x 4.075 x 3
Example 4:
Ultimate Chuck size 500 (20"), "pie" jaws weighing 65
lb. each. Static grip at 20,000 lb. to prevent crushing
the thin walled workpiece. What's the max RPM for
10,000 lb. remaining?
nmax = 20,000 – 10,000 x 188 = 509 rpm
65 x 7 x 3
Note: At 720 rpm the calculated grip force has
dropped to zero! Any small error in measurements can
have major consequences. Hence the need for actual
testing with a dynamic grip force gage.
4.7 Periodically check your jaw stroke
See section 3.1.2. Especially if you are using hard jaws
and the adjustability feature of the Ultimate Chuck, you
should regularly check your jaw stroke and compare your
actual stroke to the stroke you calculated in 3.1.2. If you
have lost any jaw stroke, check your drawtube
adjustment.
4.8 Increase hydraulic pressure 30% to achieve
same static grip force as wedge hook chucks.
In most applications, the challenge for a chuck is to
maintain grip force and hold a workpiece at high speed.
At high speed, the Ultimate Chuck will maintain a much
higher percentage of the original static grip force (static =
without the chuck rotating) than a simple wedge-hook
chuck. For this reason, you can start at a lower static grip
force and hold on to the part at high speed. This is
especially valuable for fragile parts. At the high rated
speed of the chuck, using standard ATS Systems hard
jaws gripping a diameter equal to the through hole of the
chuck, you will maintain over 65% of the static grip
force.
The Ultimate Chuck will generate higher grip forces than
simple wedge-hook chucks and will consume much
higher drawbar pull. But to generate the same static grip
force as a wedge-hook chuck you need to increase the
drawbar pull (increase hydraulic pressure) 30%. If you
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