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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 $1,230.72 +$8.10/+0.66%
Silver $15.50 +$0.20/+1.31%
Platinum $826.00 +$20.50/+2.54%
Palladium $891.00 +$24.00/+2.75%
Gold 2018-07-20 4:14 PM
Bid/Ask $1,230.72/$1,231.18
High/Low $1,232.50/$1,215.64
Change +$8.10/+0.66%
Silver 2018-07-20 4:14 PM
Bid/Ask $15.50/$15.54
High/Low $15.59/$15.20
Change +$0.20/+1.31%
Platinum 2018-07-20 4:14 PM
Bid/Ask $826.00/$830.00
High/Low $835.50/$800.50
Change +$20.50/+2.54%
Palladium 2018-07-20 4:14 PM
Bid/Ask $891.00/$901.00
High/Low $906.00/$867.00
Change +$24.00/+2.75%

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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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