Atlas of Wax Pattern Defects
Shape, Size
The geometry does not conform to intended shape/size.
Varies
Varies
Bent, Warped
Visual inspections and customary dimensional inspection tools
Distortion due to internal or external stresses occurring at wax injection, storage, or pattern assembly.
| Area | Possible Cause | Potential Correction |
|---|---|---|
| Equipment | Short cycle time |
Increase cycle time. Cycle time must be adequate to allow sufficient pattern cooling |
| Equipment | High platen temperature |
Reduce platen temperature. |
| Equipment | Clamp opening too fast |
Reduce clamp opening speed |
| Equipment | Hot wax |
Reduce wax temperature. |
| Pattern Die | Die too hot |
Reduce temperature of die or platen to control cooling. Ensure chillers are properly sized and working. |
| Pattern Die | Vacuum created |
If core pull is located in blind hole it should be withdrawn slowly to avoid producing a vacuum. At times a vent may be needed. |
| Pattern Die | Ejector pin location or design |
Review die design and rework as needed |
| Other | Opening of die too fast |
Reduce speed of die opening. |
| Other | Insufficient or improper mold release |
Use appropriate amount or type of mold release to ensure proper pattern removal. |
| Other | Improper removal of pattern from die |
Proper training of personnel for pattern removal technique or redesign die for easier removal, i.e. ejector pins Note: Use a gentle air assist by blowing along the parting line to loosen from die. Always make sure the pattern is being withdrawn evenly. Apply even hand pressure and avoid bending pattern |
| Other | Storage – placing pattern |
Use caution in storing pattern after injection. Make sure it is properly supported. In some cases, a support fixtures may be required. Materials chosen for fixturing are critical as they can cause distortion -flatness should not be assumed. (i.e. wood or flimsy plastic trays). |
| Other | Elevated temperature in wax room |
Maintain wax room at proper and consistent temperature as needed. |