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Gate/Sprue Related Porosity

Gate size and shape are important for low porosity casting. When casting simple designs with rounded shanks and only a few prongs, almost any gate - round or flared, light or heavy will function properly. A proper gate should be round and slightly smaller than the width of the shank.

A gate is designed to supply the molten metal into the pattern cavity. Assuming proper metal and flask temperatures, the gate is critical in properly filling the cavity and allowing a proper solidification. When a gate is too small, it will solidify before the part cavity. This may cause porosity at the gate-part interface. This is usually seen as a roughness or an indentation at the interface. In some circumstances, cracking may also take place, in a similar manner of a hot tear. When oxides are present, as when old metal is used, trapping of the oxides may take place. This appears as a gritty or sandy texture inside the cast part. A flared gate, hammered to expand the gate width is very popular. Flaring a gate makes it easy to engrave style number as well as increase the metal flow rate into the part.

NOTES: When solidification occurs in an angle, the outer edges solidify more rapidly causing a greater shrinkage to take place. The narrower the gate-part interface, the higher the velocity of the supplied metal. Round gates solidify in a more uniform manner than angled gates.

Precious Metal Spot Prices

  Bid Change
Gold $1,279.90 -$0.40/-0.03%
Silver $17.05 +$0.03/+0.18%
Platinum $921.00 +$0.50/+0.05%
Palladium $958.50 -$15.00/-1.54%
Gold 2017-10-23 2:50 PM
Bid/Ask $1,279.90/$1,280.70
High/Low $1,283.40/$1,272.40
Change -$0.40/-0.03%
Silver 2017-10-23 2:50 PM
Bid/Ask $17.05/$17.09
High/Low $17.14/$16.83
Change +$0.03/+0.18%
Platinum 2017-10-23 2:50 PM
Bid/Ask $921.00/$927.00
High/Low $928.00/$909.00
Change +$0.50/+0.05%
Palladium 2017-10-23 2:50 PM
Bid/Ask $958.50/$963.50
High/Low $982.00/$950.00
Change -$15.00/-1.54%

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Prices shown are for reference only. Please contact our trading desk for accurate, up-to-the-minute pricing.