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WIRTZ (BACK VENTED) VENT BAR TYPE GRID MOLD
PATENT NUMBER 3542330
During the casting operation the entrapped air is allowed to escape from the grid cavity through the back of the mold, via the patented vent bar construction.
This feature permits higher casting speeds, provides improved casting capabilities and gives longer cork life.
While applying mold coat use 20 P.S.I. air pressure for single vent bar molds and 30-50 P.S.I. air pressure for multi-vent bar molds. Attach the air pressure to the air connection (see illustration above) while applying mold coat. Before the air supply is removed, the operator should check the vents for proper operation by placing his hand over the face of the mold to detect escaping air. After the air supply is disconnected the mold is ready to cast.
If the operator is unable to detect any air escaping through vent bar, the air pressure should be gradually increased to maximum of 125 P.S.I. in an effort to clean the bar. If the operator still is unable to detect air escaping, the vent bar must be removed and cleaned.
REMOVAL AND CLEANING OF THE VENT BAR
1. The vent bar is normally located in the moveable mold half and is fastened in place from the back.
2. Remove the (5) 1/4-20 NC socket head bolts and replace with 2" or 2-1/2" long bolts. Tap bolts gently with a hammer, starting at one end; thus removing bar uniformly and not bending the vent bar.
3. Remove bolts from bar and hand wire brush internal sides of the vent bar to remove cork from vent slots on sides of vent bar. (Care must be taken not to break sharp corners).
4. Clean bottom of track in mold before replacing the vent bar.
5. Replace vent bar in slot and tap lightly with a piece of wood to return bar to flush condition with mold face.
6. Re-assemble 1/4-20 NC socket head bolts and snug the vent bar tight. (Care must be taken to insure that the bolts do not bottom in holes and strip threads). Use anti-seize compound on screw threads.
7. The mold can now be checked for proper venting by connecting air to the vent bar as stated previously.
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