Z Corporation Z 406 User Manual download pdf (Page 144)

Appendix I

ZCast Design Guide - 26

Figure 10: Attach a flexible

plastic hose like the one shown

above to reach ‘blind spots’

CAUTION

Parting lines near core vents may leak molten metal into the

vents. The vents may not function properly and cause the

unexpected release of molten metal and personal injury.

6.7 Depowderability – Fixed vs. Removable

Cores

Part depowdering refers to the removal of loose, unprinted

powder from the mold cavities following the printing process.

While the possibility to print complex geometries exists, such as

undercuts and runners that tunnel under the mold cavity, the risk

remains that all of the powder may not be removable during

depowdering. Loose powder left in the mold when metal is

poured has the possibility of affecting the outcome of the finished

casting by creating pockets or voids.

In order to avoid the aforementioned, ensure that your mold

has undergone a thorough removal of powder. In difficult to

reach areas such as blind channels and areas not visible, use

a small flexible hose like the one shown in Figure 10 to extract

loose powder.

A 1/8 in (3.2 mm) O.D. and 1/16 in (1.6 mm) I.D. urethane tube is ideal because it slides firmly

over the nozzle on the ZD4 or ZD8 depowdering units.

CAUTION

Loose powder left in molds may create pockets, voids or

block vents during metal casting resulting in the unexpected

release of molten metal. Ensure that all loose powder is

removed before casting.

CAUTION

Depowdering with compressed air will generate airborne

particles. Only trained or supervised individuals should

depowder a mold. Use hood ventilation and safety goggles

or faceshield to protect the eyes and face. Refer to the

ZCast 501 powder MSDS for more information.

6.8 Mating Surfaces

The mating surfaces of the mold should be offset to accommodate for surface imperfections. A

total gap of 0.02 in (0.51 mm) should be created, in the model, at all mating surfaces. The offset

can be created on either side of the parting surface or split between them.

Even with an intentional gap, there will likely be

some portion of the mold or core that rubs against

another part when the mold is assembled. When

one ZCast object rubs against another ZCast object,

they essentially sand each other down, leaving a

little bit of loose sand. Since this is bound to

happen, you should prepare for this by leaving room

between cores and core prints, and, where possible,

at junctions on the parting line, taking care not to

extend this gap into the path of metal. Add a small

Figure 11: Tapered core and core print.

Core has radiused bottom edge. Add

offset between mating surfaces.

Core

Drag

Rubber Hose

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