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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 $1,203.57 +$3.66/+0.30%
Silver $14.04 +$0.09/+0.64%
Platinum $842.65 +$6.65/+0.79%
Palladium $1,101.50 +$5.00/+0.45%
Gold 2018-11-12 11:40 PM
Bid/Ask $1,203.57/$1,205.07
High/Low $1,205.26/$1,200.96
Change +$3.66/+0.30%
Silver 2018-11-12 11:40 PM
Bid/Ask $14.04/$14.14
High/Low $14.11/$14.00
Change +$0.09/+0.64%
Platinum 2018-11-12 11:40 PM
Bid/Ask $842.65/$852.65
High/Low $848.30/$839.50
Change +$6.65/+0.79%
Palladium 2018-11-12 11:40 PM
Bid/Ask $1,101.50/$1,107.50
High/Low $1,113.00/$1,098.50
Change +$5.00/+0.45%

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