In one consultation with my foundry clients regarding their casting defect problems and upon evaluating their methoding practice, I have discovered that they were confused in applying density values in the risering design calculations for steel casting that is why the problem on shrinkage cavity. Wrong density choice may result to rejection due to either shrinkage or over design resulting to non-economical yield. Although mild shrinkages in steel castings might be repairable through build-up by welding, still some additional cost will be incurred, an issue on economics.
Three interesting density values of steel must be taken into mind:
1) Just above melting point for liquid low carbon steel is, 0.115 kg per cu in, as basis in calculating weight of riser in its liquid form from riser dimensions;
2) Just below the freezing point of solid steel is, 0.1195 kg per cu in, as basis in calculating casting weight from pattern dimensions; and
3) To calculate weight of casting from casting dimensions (not mold or pattern dimensions), use 0.129 kg per cu in
Erroneous density application may cause a difference in weight or volume exceeding 10%.
Shape Factor is also a major element in the design of riser but most prevalently applied in cast iron castings. It is equal to the Length plus Width of the casting which the riser must cover divided by the Main Thickness of the part where the riser is effective [(L+W)/T].
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ReplyDeleteThanks for nice sharing. You can also find best Cast Iron material at Laxmi Iron & Steel Industry. The main object of LAXMI IRON & STEEL INDUSTRIES is to provide best quality and cost effective Cast Iron. For more information Visit Cast Iron quality Casting.
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