# Number of core risers in investment casting sand casting of impeller

(1) Comparison of riser number of wheel hub in investment casting sand casting

Check whether an impeller investment casting sand casting riser is sufficient: the effective distance of an impeller investment casting sand casting riser is L = 4.5t (t casting wall thickness is approximately 50mm), then l = 4.5t = 4.5 × 50 = 225mm, the length of a riser is 180mm, then the length of an impeller investment casting sand casting riser can be reduced to

225+180=405mm。

The length of the hub edge of impeller investment casting sand casting is π d = 3.14 × 125 = 392.5mm ＜ 405mm, so a riser is set at the hub to feed.

(2) Comparison of the number of risers in the rim of impeller investment casting sand casting

Check whether the three risers are sufficient: the length of impeller investment casting sand casting rim is π d = 3.14 × 456=1431.84mm。

The effective distance of one riser of impeller investment casting sand casting is L = 4T (the wall thickness of T casting is approximately 60mm), then l = 4T = 4 × 60=240mm。 If the length of one riser itself is L = 165mm, the feeding length of the three risers is (240 + 165) × 3=405 × 3=1205mm。

Although it seems that the feeding range of the three risers of impeller investment casting sand casting is not enough, if the cold rib effect of the blade is considered, the feeding should be fully met. Therefore, it is planned to place three risers in the wheel flange part of impeller investment casting sand casting.

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