所謂熔(rong)(rong)(rong)模(mo)(mo)鑄(zhu)造(zao)工藝,簡單說(shuo)就是用易(yi)熔(rong)(rong)(rong)材料(liao)(例如(ru)蠟料(liao)或(huo)塑(su)料(liao))制(zhi)成(cheng)可(ke)熔(rong)(rong)(rong)性模(mo)(mo)型(xing)(xing)(xing)(簡稱(cheng)熔(rong)(rong)(rong)模(mo)(mo)或(huo)模(mo)(mo)型(xing)(xing)(xing)),在其上涂覆若(ruo)干層特別的耐火涂料(liao),經(jing)過干燥和硬化形成(cheng)一個整體型(xing)(xing)(xing)殼后,再(zai)用蒸(zheng)汽或(huo)熱水從型(xing)(xing)(xing)殼中(zhong)熔(rong)(rong)(rong)掉模(mo)(mo)型(xing)(xing)(xing),然后把(ba)型(xing)(xing)(xing)殼置于(yu)砂(sha)箱中(zhong),在其四周填充干砂(sha)造(zao)型(xing)(xing)(xing),后將鑄(zhu)型(xing)(xing)(xing)放入焙燒爐中(zhong)經(jing)過高(gao)溫焙燒(如(ru)采用高(gao)強(qiang)度(du)型(xing)(xing)(xing)殼時,可(ke)不(bu)必造(zao)型(xing)(xing)(xing)而將脫模(mo)(mo)后的型(xing)(xing)(xing)殼直接焙燒),鑄(zhu)型(xing)(xing)(xing)或(huo)型(xing)(xing)(xing)殼經(jing)焙燒后,于(yu)其中(zhong)澆注熔(rong)(rong)(rong)融金屬而得(de)到鑄(zhu)件。
不銹鋼精密鑄造鑄(zhu)件壓制熔模時,采用型(xing)(xing)(xing)腔(qiang)表(biao)(biao)面(mian)光潔(jie)度(du)(du)高的(de)(de)(de)壓型(xing)(xing)(xing),因此,熔模的(de)(de)(de)表(biao)(biao)面(mian)光潔(jie)度(du)(du)也比較高。此外,型(xing)(xing)(xing)殼(ke)由耐(nai)溫的(de)(de)(de)特別粘結劑和耐(nai)火(huo)材料(liao)配制成的(de)(de)(de)耐(nai)火(huo)涂料(liao)涂掛在熔模上而制成,與熔融金屬直接(jie)(jie)接(jie)(jie)觸(chu)的(de)(de)(de)型(xing)(xing)(xing)腔(qiang)內表(biao)(biao)面(mian)光潔(jie)度(du)(du)高。所以(yi),熔模鑄(zhu)件的(de)(de)(de)表(biao)(biao)面(mian)光潔(jie)度(du)(du)比一般鑄(zhu)造件的(de)(de)(de)高,一般可達Ra.1.6~3.2μm。
不(bu)銹鋼精密鑄(zhu)(zhu)造(zao)(zao)鑄(zhu)(zhu)件(jian)熔模(mo)(mo)鑄(zhu)(zhu)件(jian)尺寸精度較高(gao),一般可達CT4-6(砂型鑄(zhu)(zhu)造(zao)(zao)為(wei)CT10~13,壓鑄(zhu)(zhu)為(wei)CT5~7),當然由于熔模(mo)(mo)鑄(zhu)(zhu)造(zao)(zao)的(de)工(gong)藝過程(cheng)復雜,影響鑄(zhu)(zhu)件(jian)尺寸精度的(de)因素較多,例(li)如(ru)模(mo)(mo)料的(de)收縮、熔模(mo)(mo)的(de)變形、型殼在加熱和冷卻過程(cheng)中的(de)線量變化、合金(jin)的(de)收縮率以及在凝固過程(cheng)中鑄(zhu)(zhu)件(jian)的(de)變形等,所以普通熔模(mo)(mo)鑄(zhu)(zhu)件(jian)的(de)尺寸精度雖然較高(gao),但(dan)其一致(zhi)性仍(reng)需提高(gao)。