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 Vical acrylic, 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 Vical acrylic. 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.

Forming Acrylic Table of Contents