 The main disadvantage to die casting is the very high capital cost . Both the casting equipment required and the dies and related components are very costly , as compared to most other casting processes . Therefore , to make die casting an economic process , a large production volume is needed . Other disadvantages are that the process is limited to high @-@ fluidity metals , and casting weights must be between 30 grams ( 1 oz ) and 10 kg ( 20 lb ) . In the standard die casting process the final casting will have a small amount of porosity . This prevents any heat treating or welding , because the heat causes the gas in the pores to expand , which causes micro @-@ cracks inside the part and exfoliation of the surface . Thus a related disadvantage of die casting is that it is only for parts in which softness is acceptable . Parts needing hardening ( through hardening or case hardening ) and tempering are not cast in dies . 
