ible ▁core ▁injection ▁m old ing ▁process . ▁First , ▁a ▁core ▁is ▁made ▁from ▁a ▁fus ible ▁al loy ▁or ▁low ▁mel ting ▁temperature ▁polym er . ▁It ▁is ▁then ▁placed ▁inside ▁the ▁injection ▁m old ' s ▁dies ▁and ▁the ▁pl astic ▁is ▁shot ▁into ▁the ▁m old . ▁The ▁m old ing ▁is ▁then ▁removed ▁from ▁the ▁m old ▁with ▁the ▁core ▁still ▁in ▁it . ▁Finally , ▁the ▁core ▁is ▁m elt ed ▁or ▁was hed ▁out ▁of ▁the ▁m old ing ▁in ▁a ▁hot ▁bath . ▁ ▁Bind ers ▁Special ▁bind ers ▁are ▁introduced ▁into ▁core ▁s ands ▁to ▁add ▁strength . ▁The ▁oldest ▁b inder ▁was ▁veget able ▁oil , ▁however ▁now ▁synth etic ▁oil ▁is ▁used , ▁in ▁conj unction ▁with ▁c ere al ▁or ▁cl ay . ▁The ▁core ▁is ▁then ▁b aked ▁in ▁a ▁con ve ction ▁o ven ▁between ▁. ▁The ▁heat ▁causes ▁the ▁b inder ▁to ▁cross - link ▁or ▁polym er ize . ▁While ▁this ▁process ▁is ▁simple , ▁the ▁dimensional ▁accuracy ▁is ▁low . ▁ ▁Another ▁type ▁of ▁b inder ▁process ▁is ▁called ▁the ▁hot - box ▁process , ▁which ▁uses ▁a ▁therm os et ▁and ▁catal yst ▁for ▁a ▁b inder . ▁The ▁sand ▁with ▁the ▁b inder ▁is ▁pack ed ▁into ▁a ▁core ▁box ▁that ▁is ▁he ated ▁to ▁approximately ▁ ▁( which ▁is ▁where ▁the ▁name ▁origin ated ▁from ). ▁The ▁b inder ▁that ▁touch es ▁the ▁hot ▁surface ▁of ▁the ▁core ▁box ▁begins ▁to ▁c ure