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MACHINING CHEMCAST® GP
ACRYLIC SHEET The usual rules of good machining practice apply to the
machining of Chemcast® GP. An experienced machinist will have no
difficulty handling Chemcast® GP as soon as he gets the
"feel" of the material. Chemcast® GP has working
qualities similar to those of brass and copper. Tools and work should be held firmly to prevent chattering.
Standard metal or wood working equipment can be used, such as
milling machines, drill presses, lathes, planers and shapers. In
general, machining tools should be operated at high speeds with
slow feed rates. Tools should be sharp, clean and free of nicks
and burrs. Because it is a thermoplastic material, Chemcast® GP softens
when heated to its forming temperature. The frictional heat
generated by machining tends to soften Chemcast® GP in the
immediate vicinity of the cut and causes gumming and sticking of
the tool or tearing of the plastic if excessive heat buildup
occurs. When proper speed, feed and cutters are used, machined
Chemcast® GP surfaces will have an even, semimatte surface
which can be brought to a high polish by sanding and buffing. If tools are sharp and properly ground, coolants are seldom
required for machining Chemcast® GP. They may be desirable for
unusually smooth finish or for deep cuts. If coolants are
employed, only detergent in water or 10% soluble oil in water
should be used. Other coolants may contain chemicals harmful to
Chemcast® GP. Chemcast® GP sheet can be machined to close tolerances and
finished parts should be annealed.
For applications which require both close tolerance and good
optical properties, such as periscope prisms and lenses,
Chemcast® GP blanks should be annealed before and after
rough machining. The parts may then be machined to close
tolerance, removing as little material as possible. When final
machining is complete, the parts should be given a final
annealing. Since temperature and humidity affect the dimensions
of Chemcast® GP, machining to close tolerance must be done under
conditions like those which will prevail when the parts are
tested and put into service. Chemcast® GP acrylic plastic is a combustible thermoplastic
material. Observe fire precautions appropriate for comparable
forms of wood and paper Products. |
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Copyright © Plastiglas de Mexico 1999
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