Optimizing in Thermoforming of Plastics Parts.

Attempts are made to group three different types of thermoplastic semi-finished goods plastics sheets for their workpiece dimensions and the related deviations, using a tool with a 1 to 5 ratio of surface to bottom area. Weights have been determined and specific points in workpiece migration with respect to their thickness measured. PP was found to permit very uniform thermoforming to high wall thickness, regardless of sheet thickness, as was high-impact PS, though not to equally high wall thickness. High-impact PVC, however, tends to approach the dimensions of the PS component as sheet thickness increases. The ranges of the individual measurements and the wide variation of the measuring data require very careful specification of sheet thickness for high-impact PVC in the case of tools with large surface area. On the basis of experimental investigation allowances of 50% for PP, 25% for PS and 15% for PVC (6 mm) on the calculated value of 20% (1 to 5) can be permitted under similar conditions.