Counterweights - by polymn of a mixt of steel turnings sized cast iron granules and polyester resin

摘要

Ballast and counterweights of high density (about 6) and low cost are obtd. by polymsn. in moulds of mixts. of 50 plus-or-minus 3% of 6/15 and 15/30 steel turnings 25 plus-or-minus 56 of No 4-5-6 granules of cast iron or steel, 21 plus-or-minus 8% pref. 21-21.56 of No. 100 granules of cast iron or steel and 3.5-4% polyester resin plus catalyst and activator. The fines are first mixed with catalysed resin and larger particles added and finally the activator before moulding under vibration to prevent air bubbles forming.