Why It’s Important To Know Melt Temperature In Injection Molding

Melt Temperature is one of the four major variables that affect part quality.  The remaining three are fill speed, pack pressure, and cooling rate.
Melt temperature directly affects the viscosity (resistance to flow) of the resin. That is the thinness or thickness of the resin.  If the resin is too thick it will not fill the cavity or part completely causing inconsistent shrinkage and dimensional variations.  Short shots may also occur.  Thick resin will have issues filling textures and gloss level will vary over the part surface.
Too thin of resin will cause flash and dimensional issues at the parting line.
All Resin suppliers have a recommended process or melt temperature and must process these resins within those ranges to keep them from degrading.  If the resin degrades, the polymer chain will be damaged and physical characteristics will be jeopardized. The part will be brittle.
We (MTMS) recommended you optimize your melt temperature per the resin manufacturer’s recommendations at sampling (Validation or PPAP).  Then measure the temperature with the MTMS kit and record this temperature on a master setup sheet.  This temperature should be matched, utilizing the MTMS kit for all future lots to obtain optimum quality for the life of the program.