Melt Temp Is Not Barrel Temp

According to RJG and world class injection molders, melt temperature is one of the four major variables required to make high quality parts, however many molders do not realize the barrel temperature is not the melt or process temperature.The melt or process temperature, as recommended by the material supplier, is the purge or output temperature from the injection molding press. Five variables affect the melt temperature, they are barrel temperature (controlled by heater bands), screw RPM, backpressure, screw design, and residence time.The barrel heater bands only accounts for 25% to 30% of the heat in the melt.  The majority of the heat come from the screw RPM and backpressure through shear.  The screw design and type also induces shear into the melt.  The residence time also affects the melt temperature as the faster the cycle the more heat required to keep up with the melt.The interactions between these variables and the ability for a specific resin to respond to shear will affect the melt temperature.If you want continuous improvement in your injection molding process it is mandatory to know your melt temperature.  For more information on how to measure your melt temperature accurately and precisely, go to www.plasticmelttemp.com .

Do You Know Your Melt Temp?

-Rich Bleck50 year veteran of the injection molding industry & inventor of the MTMS Kit