Venting bore hole

The number and diameter of venting bore holes and the width of the venting slots have to be dimensioned sufficiently large to allow a fast venting (exhaustion). On the other hand, the vents should not leave any markings at the molded product. 

The venting bore hole on the surface of the mold dj should after 2 to 4 mm become the larger diameter d.2 and the larger width of the venting channel d. Venting bore holes d) that are too long (deep) can reduce the venting velocity and are harder to drill. 

Step 1 inserting anchor bolt and setting up the injection long pipe and air vent short pipe in the bore hole. 

Diaphragm between hole-plates 3, rod 4, Seal bushing 5, Snifiting valve 6, Connecting bore 7, Venting valve 8, Plunger. 

Venting can also be provided within the mold cavity by means of inserts equiped with vent slots, porous sintered plugs, or by holes with a diameter not greater than 0.2 mm. Such holes are machined only to a shallow depth and are relieved by a much larger bore machined from the back of the mold. 

Drill 1/8" diameter vent holes and bore the centers as indicated.(fig.five) If you lack the experience and tools to generate a helix as shown, you have two options. Farm out the job to a local machine shop, or use a substitute spiral unit. Two examples are found in the AR-7 silencer in PMA Vol.l and the De Lisle Carbine detailed in this issue. 

The secondary seal contact surface(s) shall not exceed a roughness of 63 min. (1.6 (jim). Seal chamber bore comers and entry holes, such as those used for flushing or venting, shall be suitably chamfered or rounded to prevent damage to secondary seals at assembly. 

Before the final reaming and lapping operations are performed on the sleeve, four parallel rows of vent holes should be drilled along the axis of the bore. These allow gas to vent into the absorbent material surrounding the... 

Checking for contaminated 0-ring counter bores, pitting and damaged plates, dirty tooling and vent channels, sloppy pin or bushing holes in moulds. 

Eastman Kodak Company received a patent (U,S. Patent 6,164,810) on a barrier screw with a vent hole located within about two diameters from the end of the feed section, between a main flight and a barrier flight. The vent hole is located such that there is little chance of polymer plugging the vent hole. The volatiles are vented out to the back of the screw through an axial bore. This screw design can be used to process PET powder into film. 

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