User manual

Appendix I
ZCast Design Guide - 13
5 Designing with ZCast – Mold Design
ZCast powder 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 when
using other methods. ZCast’s unprecedented flexibility allows the designer to choose the
technique that is the most proper for the application at hand.
CAUTION
Improper design of molds can result in the release of molten
metal and personal injury during the metal casting steps.
Only trained or supervised individuals should design molds.
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 will be at designing complex and challenging parts. By contrast, simple parts
require simple gating and are more straight forward. If you do not have the experience, but have
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 patterns. Some of the special
properties of ZCast powder affect some of the design
considerations. To make high-quality castings, a strong
emphasis should be placed in the design of risers. 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 during solidification.
Figure 3: Direct pour molds in
aluminum after pouring (note
significant number of risers).