User manual

Appendix I
ZCast Design Guide - 19
6 Design Techniques with ZCast Patterns
6.1 Direct Gating
Conventional methods of runner design are based on having a flat pattern that must be drawn out
of a sand mold. This forces the runners and gates out sideways resulting in a mold that covers a
larger area. Such a design can exceed the size of the build volume of the 3D Printer. Consider
bypassing the runner system entirely by gating the sprue and risers. This allows for a simple,
compact design which can easily be printed.
6.2 Mold Parts Larger Than Build Volume
It is quite possible that your mold will exceed the size of the build volume of your Z Corp. Printer.
Multiple sections of the mold can be printed and assembled separately. Use core paste between
the shell seams to ‘bridge’ the shell section together. Clamp the mold halves together with dowel
pins for alignment.
WARNING
Do not cast molten metal in molds with multiple sections
without using core paste or adhesive. Molten metal can leak
from the mold and cause personal injury.
6.3 Shelling your Mold
As will be discussed in the ‘Mold Preparation’ section, baking is a requirement for all ZCast
molds. To ensure thorough baking throughout the entire mold, hollow out the backside of your
mold for better performance. Take the following example: Figure 6a illustrates a mold cavity
surrounded by a solid mass of ZCast material. Figure 6b shows the same mold with a section
passing through it for clarity. With a thick section of ZCast powder, it becomes difficult for the heat
to penetrate the depths at uniform levels. Figure 6c illustrates the same mold with a section view.
This is the optimal situation. With uniformity to the walls throughout, it is easier for the heat to
thoroughly disperse throughout the mold.
WARNING
Unshelled molds may not bake thoroughly to remove all
residual moisture. Residual mold moisture after baking when
contacted with molten metal can cause the unexpected
release of molten metal from the mold and personal injury.
Figures 6b: Unshelled section view Figures 6a: Unshelled solid Figures 6c: Shelled section view