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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 $1,286.38 +$1.39/+0.11%
Silver $17.02 +$0.03/+0.18%
Platinum $976.00 +$1.50/+0.15%
Palladium $927.00 -$2.50/-0.27%
Gold 2017-08-23 2:23 AM
Bid/Ask $1,286.38/$1,286.47
High/Low $1,286.98/$1,282.50
Change +$1.39/+0.11%
Silver 2017-08-23 2:23 AM
Bid/Ask $17.02/$17.03
High/Low $17.06/$16.89
Change +$0.03/+0.18%
Platinum 2017-08-23 2:23 AM
Bid/Ask $976.00/$981.00
High/Low $982.00/$972.00
Change +$1.50/+0.15%
Palladium 2017-08-23 2:23 AM
Bid/Ask $927.00/$939.00
High/Low $939.00/$924.00
Change -$2.50/-0.27%

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