Improper mold venting can, and frequently does, cause a multitude of processing problems, but now a patented, scientific method and device to help check for proper venting conditions is on the way.
Process & Design Technologies LLC, a consulting firm dedicated to providing solutions for plastics processing issues, has been issued a patent for "Apparatus and Method for checking mold vent condition." P&DT principal Terry L. Schwenk has been working to promote scientific venting for a number of years.
"Scientific venting principles are based on volume displacement over time versus the typical method which involves the vents being calculated as a function of flashing of the material," Schwenk says. "Air and/or gas in the cavity need to be displaced by the molten plastic. If you have poor venting, it will require more pressure and time to displace the air and/or gas in the cavity, with heat being generated as a byproduct."