Mold Temperature. Injection Speed and Molding Cycle
2.4 Mold Temperature, Injection Speed and Molding Cycle
(1) Mold Temperature
Being high in crystallization speed, DURANEX® PBT results in products with relatively glossy surfaces at the mold temperature between 40°C and 120°C. The higher the mold temperature, the better the surface gloss and dimensional stability but the larger the deformation becomes. A countermeasure for such deformation is to use lower mold temperatures, but this results in a larger deformation during annealing or use at elevated temperatures; thus precautions regarding these points are required.
(2) Injection Speed
Since DURANEX solidifies very quickly, faster injection speeds result in parts with glossier surfaces. High speed injection, however, tends to cause burn marks on the parts, so thorough consideration must be given to the gas venting.
(3) Molding Cycle
The rapid solidifying speed of DURANEX makes it possible to manufacture parts with a relatively short cycle. In order to avoid sink marks or deformation and to decrease dimensional scattering, it is necessary to select an injection and dwell time slightly longer than the gate seal time.