Lifting

LiftingLifting presents as a wobbly leather-like surface and is typically the second stage of a buckling defect. This indicates that the sides of the pyramid cracked and prewet and/or slurry trapped in the shell has seeped through the cracks and filled the shell cavity.

The causes of this defect are evident in the wax and shell portions of the process. To cure these causes, R&R recommends taking the following actions.

 

Area

Cause

Cure

Wax

  1. The wax pattern was not washed properly and the first slurry coat could not adhere properly to the wax pattern.
  1. Improve pattern washing technique, ensuring that the release agent is removed from the pattern and the pattern wash is still effective.

Shell

  1. The primary binder is not adhering to the pattern sufficiently (low quality primary binder with poor wetting/adhesion characteristics). As the layer dries, it experiences stress and contracts or flakes.
  1. Use a high quality primary binder with good wetting/adhesion characteristics that is resistant to drying stresses. Polymer-containing binders reduce the propensity of colloidal silica to contract and flake as it dries.

Metal

 

 

Other

 

 

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