All casting forms a cavity into which the melt is poured. The variation is in the methods by which the cavity is formed. Die casting uses a machined metal cavity for the part forming, with various approaches to introducing fill material and mechanization of the process. Investment casting uses a plaster cavity cast over a then volatilized pattern or master. Various options exist in pattern material and fill technique, from simple hand pour to full automation. Meanwhile, metal injection molding uses polymer-bonded, powdered metal feedstock, which is molded in machined steel cavities, processed, and finally sintered. Sand casting uses a variety of techniques from entirely manual to fully automated, and even automated core production/placement to form cavities using bonded sand which is then machine-charged and de-molded.
