Apr 24, 2014

Vacuum casting

Vacuum molding is the process used in both types of the casting that is permanent mold and expandable mold casting. We have already written about the vacuum molding process of expandable mold type and now we will learn about vacuum molding of permanent mold type. In permanent mold vacuum casting molten metal is forced into the casting cavity through the gating system.

Steps involves in vacuum molding

Step 1

An especially design mold cavity is made for this process. Having the gating system at the bottom and casting cavity at the top. Molten metal will rise from bottom to the top

Mold For Vacuum Casting

Step 2

Mold cavity is place over the tank having the molten metal

Mold Over Supply Of Molten Metal

Step 3

Vacuum is applied at the top of the mold and molten metal is sucked up through the gating system and toward the casting cavity. Vacuum is applied until metal in the mold is solidifies

Force Fills Mold

Step 4

Vacuum is removed and mold is open to remove the cast part

Advantages of vacuum casting

  • Good dimensional accuracy
  • Good surface finish
  • Good mechanical properties
  • Reduction in the defects caused by the gases as it uses the vacuum force instead of air pressure used by expandable mold

Disadvantages of vacuum casting

  • High initial cast
  • Complex mold making
  • Only suitable for mass production


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