Process Tips

While this process yields good castings, several issues remain for the foundry:

  1.  Manual labor is required to add vents to the pattern, open the vents after the shell is built, melt out the sprue and runners, patch the vents, and clean the ash out of the shell. Melting the sprue by hand alone typically takes half an hour or more of labor. All the associated manual labor adds significantly to the cost of processing a QuickCast pattern.

  1. For foundries with only one furnace, lowering the temperature to below the cristobalite conversion temperature to burn out the pattern means that normal production has to stop for that period, further increasing processing cost.

  1. At several steps in the process, there are significant deviations from the normal process the foundry uses. Every such deviation is an opportunity for a mistake to be made, potentially resulting in a failed casting. Given that the cost of QuickCast patterns is high, and there is significant additional cost to process a QuickCast pattern, the cost of failure can be much higher than for a molded wax pattern. In addition, it may take a few days to obtain a replacement pattern and the resulting delay in delivering a casting to the customer may be longer than for the traditional wax method.

3D Systems has worked with several foundries and shell suppliers as well as developing new resins and build styles to improve the procedures for evacuating the shell. This will increase casting yields and reduce the cost of casting. Additionally, a number of key process improvements have been identified that greatly simplify the processing of QuickCast patterns.

Efforts were concentrated in the three areas that in the past have been most problematic for foundries:

  1. Use of the autoclave to remove wax components of the assembly.

  2. Burnout of the QuickCast pattern.

  3. Ash removal.