Time really fled, and today I heard a colleague lament that another year is about to pass. Today is September 26th, and one month is almost over, and soon I will be celebrating the 11th Golden Week and the Golden Autumn October. Time is always slipping away from the fingers, and I can’t catch it. Ok, today, the editor of Dongguan Plastic Mould Factory introduces the material PBT used in plastic mold injection molding.
The PBT chemical name is polybutylene terephthalate. Typical applications: household appliances (food processing blades, vacuum cleaner components, electric fans, hair dryer housings, coffee utensils, etc.), electrical components (switches, motor housings, fuse boxes, computer keyboard keys, etc.), automotive industry ( Radiator windows, body panels, wheel covers, door and window components, etc.).
Injection Molding Process Conditions: Drying: This material is easily hydrolyzed at high temperatures, so drying prior to processing is important. It is recommended to dry in air at 120C, 6~8 hours, or 150C for 2~4 hours. The humidity must be less than 0.03%. If drying with a hygroscopic dryer, the recommended conditions are 150C, 2.5 hours 熔化. Melting temperature: 225~275C, recommended temperature: 250C. Mold temperature: 40 to 60 C for unreinforced materials. The cooling channel of the mold is well designed to reduce the bending of the plastic part. The loss of heat must be fast and even. It is recommended that the mold cooling channel has a diameter of 12 mm. Injection pressure: medium (up to 1500 bar). Injection speed: The injection speed should be as fast as possible (because PBT solidifies quickly). Runners and gates: Circular runners are recommended to increase pressure transfer (empirical formula: runner diameter = plastic thickness + 1.5mm). Various types of gates can be used. Hot runners can also be used, but care should be taken to prevent leakage and degradation of the material. The gate diameter should be between 0.8 and 1.0*t, where t is the thickness of the plastic part. If it is a submerged gate, the recommended minimum diameter is 0.75mm.
Chemical and physical properties: PBT is one of the toughest engineering thermoplastics. It is a semi-crystalline material with excellent chemical stability, mechanical strength, electrical insulation properties and thermal stability. These materials are very stable under a wide range of environmental conditions. PBT has a weak hygroscopic property. The tensile strength of the non-reinforced PBT was 50 MPa, and the tensile strength of the glass additive type PBT was 170 MPa. Excessive glass additives will cause the material to become brittle. PBT; crystallization is very rapid, which will cause bending deformation due to uneven cooling. For materials with a glass additive type, the shrinkage in the process direction can be reduced, but the shrinkage in the direction perpendicular to the process is essentially indistinguishable from that of ordinary materials. Generally, the material shrinkage rate is between 1.5% and 2.8%. Materials containing 30% glass additives shrink between 0.3% and 1.6%. The melting point (225% C) and the high temperature deformation temperature are both lower than the PET material. The Vicat softening temperature is approximately 170C. The glass trasitio temperature is between 22C and 43C. Due to the high crystallization rate of PBT, its viscosity is very low, and the cycle time of plastic parts processing is generally low.
Note: The above information from the Jiezheng mold finishing on the Internet, welcome reproduced, indicate the source!