Appendix I
ZCast Design Guide - 8
5 Designing with ZCast – Mold Design
ZCast offers flexibility and simplicity in mold design. Because of its simplicity, the engineer or
designer can spend more time focusing on the design of the part rather than on the design of the
mold. This simplicity does away with undercuts and draft which are critical using other methods.
ZCast’s unprecedented flexibility allows the designer to choose the technique that’s the most
proper for the application at hand.
5.1 Sources of Mold Design Information
The subtleties of casting design are beyond the scope of this document. The designer may wish
to gain as much information as possible on designing sand molds before attempting to use the
ZCast process. The more knowledge one possesses about good mold design, the more
successful you’ll be at designing complex and challenging parts. By contrast, simple parts require
simple gating and more straight forward. If you don’t have the experience, but have the complex
parts, consult a local experienced foundryman. They should be capable of helping you design
your mold properly.
Several references are available on the topic of designing castings. There are numerous
publications be the American Foundry Society, as well as textbooks. Among the best of these
are: Campbell, J., Castings, Butterworth Heinemann, 2000: Heine, R.W.; and Rosenthal, P.C.,
Principles of Metal Casting, McGraw-Hill, 1955: Ammen, C.W., The Complete Handbook of Sand
Casting, Tab Books (McGraw-Hill), 1979.
Important aspects in good mold design are:
Even filling of the mold
Accurate cooling of the casting
Proper
mold
ventilation
The conventional features of designing molds for sand casting apply equally well to ZCast use.
Some of the special properties of ZCast powder affect some of the design considerations, and
these will be discussed below.
Properties of light metals such as aluminum and magnesium
cause them to be especially sensitive to exposure to air,
water vapor, and mold gases. Gating design for these
metals should focus on minimizing turbulence during filling.
These metals also tend to shrink a great deal on during
solidification. To make high-quality castings, a strong
emphasis should be placed in the design of risers.
5.2 Selecting a Design Method
This first step in designing a mold using the ZCast process is
to decide which design method best suits the desired
casting. These are the three basic methods.
Figure 3: Direct pour molds in
aluminum after pouring (note
significant number of risers).
