ProtoMetals is a small company active in rapid prototyping of complex shapes. Their main technology is lost wax casting in plaster moulds. When casting thin walled, elongated and curved shaped, scar-type defects have been observed at the external surface. Hot tears were suspected. After grinding most of the scars disappear. Most of the scars had protrusion that could be felt by touching. ProtoMetals asked M2i to perform an investigation of the structure and to advise on the reason of the defect.
Objectives
• ProtoMetals is a small company active in rapid prototyping of complex shapes. The main technology is lost wax casting in plaster moulds.
• When casting thin walled, elongated and curved shapes, scar-type defects have been observed at the external surface.
Topics
• Analyzing the microstructure.
• Determination of the cause of the defect.
• Advise about process modifications.
Benefits
• Cause of failure was determined in a short microstructural investigation.
• Modification of several process parameters was advised.
• Reply from the director of ProtoMetals Ron Klaus:
“As M2i said, there were some problems in the microstructure. After we changed the burn-out cycle, did better degassing and stopped the vacuum directly after casting, the parts looked fine”
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