The main injection molding conditions for PBT.

Update:29 Sep 2018
Summary:

1) Barrel temperature. The choice of barrel temperature […]

1) Barrel temperature. The choice of barrel temperature is very important for the formation of PBT. For example, if the temperature is too low and the plasticization is poor, it will cause defects such as material shortage, dent, uneven shrinkage and dullness. If the temperature is too high, the nozzle will be severely flowed, overflowing, darkening and even degrading. Generally, the barrel temperature is controlled at 240~280°C, and the glass fiber reinforced PBT is controlled at 230~260°C. The nozzle temperature should be controlled below the temperature of the front section of the barrel by 5~10 °C.

2) Mold temperature. The mold temperature is directly related to the dimensional stability, warpage, molding cycle and crystallinity of the product. PBT is easy to crystallize, and it crystallizes rapidly even at normal temperature, so the mold temperature does not need to be too high, usually 40 to 60 ° C, while the glass fiber reinforced PBT has a slightly higher mold temperature, usually 60 to 80 ° C.

3) Injection pressure. PBT melt viscosity is low, fluidity is good, moderate injection pressure can be used, generally 60~90MPa, glass fiber reinforced PBT is 80~100MPa, usually the injection pressure increases with the increase of plastic part thickness, but not more than 100MPa Otherwise, it will make the demoulding difficult.