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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 $1,270.95 -$1.55/-0.12%
Silver $14.77 -$0.19/-1.27%
Platinum $883.00 -$10.00/-1.11%
Palladium $1,387.01 +$1.51/+0.11%
Gold 2019-04-23 2:01 PM
Bid/Ask $1,270.95/$1,272.45
High/Low $1,276.57/$1,266.43
Change -$1.55/-0.12%
Silver 2019-04-23 2:01 PM
Bid/Ask $14.77/$14.87
High/Low $15.04/$14.75
Change -$0.19/-1.27%
Platinum 2019-04-23 2:01 PM
Bid/Ask $883.00/$893.00
High/Low $902.00/$881.19
Change -$10.00/-1.11%
Palladium 2019-04-23 2:01 PM
Bid/Ask $1,387.01/$1,393.01
High/Low $1,396.30/$1,367.15
Change +$1.51/+0.11%

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

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