Investment Casting

Investment casting machine

Mechanical part made by investment casting

Recepticle made by investment casting

Investment casting is a process that produces metal parts from a mold using some variation of the following steps:

• A pattern is made which is a positive replica of the final part 
• The pattern is used to make a negative rubber mold
• The rubber mold is used to make a positive wax replica of the final part
• The wax is surrounded by investment compound
  
• The investment compound is hardened
  
• The wax is burned or melted away leaving a cavity
• The cavity is filled with the material of the final part using pressure, vacuum, or centrifugal force.
• The part is cooled.
• The investment compound is removed
  

Investment casting provides close dimensional accuracy, good repeatability, requires little or no draft, has no parting line and provides a good surface finish. The process can be applied to a wide variety of 3D parts, including those with intricate internal and external features and shapes with little or no draft.

Investment casting is often used in making jewelry and other small parts but is also used in the aerospace, power generation, firearms military, medical, commercial and automotive industries. 

Investment casting is generally more expensive than die casting but can produce more complicated shapes. The process can be used with most metals.

The main options for cost reduction are to minimize the size and weight of the part.

Investment Casting Design considerations

• The shape must allow for the investment compound to be removed.