Best results can be achieved by drilling a vent hole into the bottom of the pin (Figure #1). This procedure considerably shortens the "escape route" for gas.

Since highest permeability can be achieved with an EDM finish, it is desirable to EDM the bottom and sides of the drilled hole for better efficiency (Figure #2). Be sure all EDM fluids are cleaned out before installing the pin into the tool.

It is best to grind the outside diameter of the pin, or install a copper, brass, or plastic tube inside the drilled hole if a blowback system is used (Figure #3). This allows concentration of air pressure in an area where it is needed most (next to the molding surface).

The age-old venting problems that have faced molders for years have been solved using Porcerax II venting steel. Better mold cavity venting adds many benefits, from reduction of scrap to better cycle times. Whether it is a retrofit or engineered into the tool from the start, Porcerax II adds value to all molds.