We work with our customers to try to minimize sink and knitlines during our DFM process.
- Sink (a physical depression on the surface of a part) frequently occurs around thicker sections. If the rib is the same thickness as the wall, the intersection of the two creates a localized thick wall and is susceptible to sink
- Decreasing the thickness of the supporting rib eliminates or reduces the potential for sinks. Generally, the thickness of the rib should be about 75% of the thickness of the wall
- Knitlines can occur when two flow paths or material meet in the cavity and when the flow path is relatively long
- Visually, negligible knitlines on properly designed MIM parts are superficial and do not represent a structural defect or part performance issue. Generally, knitlines of this type have a shallow witness that is as little as .0005” deep to .005” deep