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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 $1,244.45 -$0.35/-0.03%
Silver $14.71 +$0.02/+0.14%
Platinum $799.85 +$1.35/+0.17%
Palladium $1,266.47 +$7.97/+0.63%
Gold 2018-12-13 3:30 AM
Bid/Ask $1,244.45/$1,245.95
High/Low $1,246.80/$1,244.00
Change -$0.35/-0.03%
Silver 2018-12-13 3:30 AM
Bid/Ask $14.71/$14.81
High/Low $14.82/$14.72
Change +$0.02/+0.14%
Platinum 2018-12-13 3:30 AM
Bid/Ask $799.85/$809.85
High/Low $808.01/$802.75
Change +$1.35/+0.17%
Palladium 2018-12-13 3:30 AM
Bid/Ask $1,266.47/$1,272.47
High/Low $1,272.15/$1,260.24
Change +$7.97/+0.63%

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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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