Solid injection moulding parts prodn. - by injecting plastic smelt into mould with part formed during setting phase, then cooling in bath of liq. nitrogen@

摘要

The plastic smelt is injected into a mould, and during the setting phase the moulded parts are formed, then cooled in a bath contg. a cold medium. As cold medium, a liq. inert gas, pref. nitrogen, is used at -196 deg. C which on contact with the plastic part evaporates. The length of time the part remains in the bath of cold medium is pref. between 10 and 20 seconds. USE/ADVANTAGE - Used to form injection moulded thermoplastic parts with no surface imperfections.