ThorPlas Engineering Manual - Thordon Bearings

MACHINING INSTRUCTIONS
d) Step-By-Step Machining Process
Steps 1 through 7 illustrate the machining process for
ThorPlas in a standard lathe.
Step 1. Cut part allowing extra length for chucking,
parting off and facing. Typically chucking lengths of
25mm (1”) are sufficient for bearings up to 152mm
(6”) O.D.
For large parts - O.D. in excess of 152mm (6”), thin wall
bearings and/or for parts with tighter than standard
tolerances, an internal plug or “chucking ring” is
recommended to support the bearing in the chuck jaws.
Step 2a. Set the part in the chuck jaws as shown below.
These figures show a piece with sizes of 76.2mm O.D. x
25mm I.D. (3” x 1”) squared in the chuck using a threejaw
configuration. Use light to moderate clamping forces.
Do not over clamp as this can cause stresses in the
material resulting in cracking.
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Step 2b. For parts needing a metal chucking ring,
machine slightly the O.D. to clean uneven surfaces and
machine the I.D. so that the chucking ring has a slight
interference with the ThorPlas - interference of 0.03mm
(0.001”). Typical thickness of chucking rings vary from
12mm (0.5”) for small parts to as high as 25mm (1.0”)
for parts with O.D. values in excess of 250mm (10”).
Figures below show a ThorPlas bearing, size of 152mm
(6.0”) O.D., where a chucking ring is used for extra
support.