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CONTOUR TOLERANCES AND EFFECTS OF FORMING Contour tolerances of + 1/8" can be maintained in
many forming operations, but for freeblown sections,
particularly in large sizes, tolerances of up to + I/2~,
may have to be allowed. The reduction in thickness caused by deep
drawing will tend to lighten the color or translucency of colored
Chemcast® GP, so that the color of the drawn pieces may not
match the original color of the flat sheet, especially where the
part is viewed with transmitted light. This graduation of color
can be used to advantage in such applications as lighting fixture
shields. SHRINKABLE ALLOWANCES When the final dimensions of the formed parts are
critical, forms must be built sufficiently oversize to allow for
shrinkage when the parts cool from forming temperature to room
temperature. A shrinkage allowance of approximately 3/32"
per foot should be made in designing forms for Chemcast® GP.
Also, surfaces of the forms should extend beyond the trim line.
This permits the use of slightly oversize sheets which simplifies
handling and compensates for the slight tendency of the plastic
to curl away from the form and flare at the edges. |
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Copyright © Plastiglas de Mexico 1999
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