Design Criteria -- The gating system (sprues,
runners, and gates) provides paths for the molten metal to flow into the mold. For steel
castings, it is important that the mold fills quickly, but turbulent flow needs to be
avoided.
- Molten steel "freezes" quickly, so the mold need to fill rapidly from multiple
directions.
- But turbulent, high velocity metal flow promotes "reoxidation" with the
formation of non-metallic inclusions.
- Runners and gates have to promote high volume, low velocity flow.
- The runners and gates need to be integrated with the placement of the risers
.
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| Example of a Sprue in the
Cope and Runner and Gates in the Drag |
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