Process requirements of PBT material in injection molding
PBT material is a thermoplastic polyester with excellent electrical insulation property and is an ideal material for manufacturing electronics.
The processing properties of PBT materials are as follows:
1. PBT material is more sensitive to moisture at high temperatures and needs to be dried before mass production.
2. Melted PBT has excellent fluidity and can be used to make thin-walled products.
3. The crystallization speed of PBT is fast, so we can raise the injection speed in the injection molding process.
4. The shrinkage rate of PBT is larger, which is more obvious than that of other plastic materials.
5. For the product design, all corners should be transitioned by arcs as much as possible.
6. Both PBT and modified PBT can be processed with the cold runner, but glass fiber reinforced PBT requires a hot runner system to achieve a better product appearance.
7. The gate position is best to face the cavity and core, to avoid the spray of melted material and reduce the possibilities of defects on the product surface.
The main conditions required in PBT molding:
The temperature of the barrel. In the molding process, the barrel temperature should be controlled at 240-280℃, and the glass fiber reinforced PBT should be controlled at 230-260℃。
Mold temperature. The mold temperature is directly related to the dimensional stability and product deformation. PBT material is easy to crystallize, so the mold temperature can be 40-60℃ around.
Injection pressure. The melted PBT has good fluidity, we can adopt a moderate injection pressure. For glass-fiber-reinforced PBT or products with thicker walls, it is necessary to increase the injection pressure accordingly.
