Z Corporation Z 406 User Manual download pdf (Page 145)

Appendix I

ZCast Design Guide - 27

radius to the bottom edges of core prints where they sit in the cope or drag; this provides space

for loose powder to collect safely away from metal flow.

A foundry will typically seal parting surfaces with core paste. A bead of this material is placed

around the outer edges of the mating surfaces of the mold and across the core prints to prevent

leakage.

6.9 Geometry Guidelines

For the majority of metals that can be poured in ZCast 501 molds, the following are the geometric

limitations:

• Minimum core size – 0.14 to 0.16 in (3.5 to 4.0 mm); some distortion will occur if small

cores project across large distances.

• Minimum cast feature size (positive feature) – 0.12 in (3.0 mm); thinner ribs have been

cast but there are limits on how far the feature can extend.

• Volume – no tested limit. Size limitations are related to build size. However, molds can

also be built in sections and assembled to make much larger molds.

• Closed/nearly closed volumes – if the core does not have enough body at the core print

to support itself (for example, the core of a two liter soda bottle – very narrow neck with

respect to the size of the core), then the core may break in the mold. If the core narrows

down at the core print so that the bulk of the core cannot be vented, then there is risk of

high porosity in the casting.

6.10 Wall Thickness Guidelines

As indicated in the section 6.3 ‘Shelling Your Mold’, thinner sections bake quicker and more

efficiently. Maintain the following guidelines for modeling your mold with thin walls:

• Any mold wall that is in contact with metal should be no less then 0.5 in (13 mm) thick,

and no more than 1 in (25.4 mm) thick (with exceptions below).

• The mold should be able to sit square on a base for pouring.

• Ribs should be added where necessary to provide rigidity (typically in the drag, where a

supporting surface is being built up). Ribs should be about 0.5 in (13 mm) thick.

• Maintain large enough areas for clamping.

• Use “off the shelf” pouring cups and risers

CAUTION

Mold wall thicknesses of less than 0.5 inches (13 mm) may allow

molten metal to leak from the mold unexpectedly and cause

personal injury. Design molds to ensure at least 0.5 inches (13

mm) mold wall thickness.

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Z Corporation Z 406 User Manual Page 145