Plastic workpiece mfr. with flat top and uneven bottom surfaces

摘要

A method for producing a plastic workpiece (1), particularly with solid fibre insert, and with smooth top surface (2b) and with knobs and ribs (3) on the underside (4) in a press tool and/or injection moulding tool comprises applying pressure (K) during the shrinkage process so the extra shrinkage of the projections on the underside is compensated and the shrinkage (6) from a flat surface (2a) on the upper side does not contain additional shrinkage (5a) and a flat surface results. Pressure may be introduced by a dwell pressure slide valve, by sprung members or via sintered metal inserts and/or needle valves.