Investment Casting Process in Dentistry

Investment Casting Process

Describe with a diagram various parts of a dental casting mold.
Answer:

Following is the diagram of various parts of the dental casting mold:

1. A.Crucible former
2. B. Sprue
3. C. Cavity formed by wax pattern after burnout
4. D. Investment
5. E. Liner
6. F. Casting ring
7. G. Recommended maximum investment thickness of approximately 6 mm

• Crucible former: It is a heat-resistant container in which alloy is melted prior to casting. It is made up of clay, carbon, quart, and ceramic.
• Sprue former: It is a device that provides a channel through which the molten alloy can reach the mold space in an invested ring after the wax has been eliminated.
• Following are the functions of sprue former:
  • It forms a mount for the wax pattern.
  • It creates a channel for the elimination of wax during burnout.
  • It forms a channel for the entry of molten alloy during casting.
  • It provides a reservoir for molten metal which compensates for alloy shrinkage during solidification.
• Wax pattern: It is the pattern of a final restoration which is made with type II inlay wax or other casting waxes with all precautions to avoid distortion. Before making the pattern a die lubricant is applied to help separate the wax pattern from the die.
• Investment: An investment is described as a ceramic material that is suitable for forming a mold in which molten metal or alloy is cast.
• Ring liner: A thin uniform sheet of material that is lined on the internal surface of the casting ring to facilitate the uniform expansion of the investment.
• The following are the functions of ring liner:
  • It allows for mold expansion
  • As the ring is transferred from the furnace to the casting machine it reduces heat loss as it is a thermal insulator.
  • It permits easy removal of investment after casting.
• Casting ring: It is made up of corrosion-resistant alloys to withstand high temperatures and corrosion.