Today is August 31st, the last day of August. After the summer vacation today, it can be said that it is exactly over. At the same time, it is the end of the month. At this time, the bosses of Dongguan Plastic Mould Ok, I haven't updated the website for everyone for a long time. Today I will introduce the injection molding process of PBT material in plastic mold injection processing.
First, we will introduce the typical application range of PBT materials: household appliances (food processing blades, vacuum cleaner components, electric fans, hair dryer housings, coffee utensils, etc.), electrical components (switches, motor casings, fuse boxes, computer Keyboards). Buttons, etc., automotive industry (heatsink windows, body panels, wheel covers, door and window components, etc.).
Next, let's look at the injection molding process conditions of PBT plastic materials:
1. Drying treatment: This material is easily hydrolyzed at high temperatures, so drying treatment before processing is very important. It is recommended to dry in air at 120C, 6~8 hours, or 150C for 2~4 hours. Less than 0.03%. If drying with a hygroscopic dryer, the recommended condition is 150C, 2.5 hours?
2. Melting temperature: 225~275C, recommended temperature: 250C.
3. The temperature of the mold is well designed to reduce the bending of the plastic parts. The loss of heat must be fast and even. It is recommended that the mold cooling channel has a Diameter of 12 mm.
4. Injection pressure: medium (up to 1500 bar).
5. Injection speed: The injection speed should be as fast as possible (because PBT solidifies quickly).
6. Runners and gates: It is recommended to use a circular runner to increase the 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 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.
Finally, let's take a look at its physical properties: PBT is one of the toughest engineering thermoplastics. It is a semi-crystalline material with very good chemical stability, mechanical strength, electrical insulation properties and thermal stability. PBT has a weak hygroscopic property. The tensile strength of the non-reinforced PBT is 50 MPa, and the tensile strength of the PBT of the glass additive type is 170 MPa. Excessive glass additives will cause the material to The crystallization of PBT 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 vertical direction to the process is In general, the material shrinkage rate is between 1.5% and 2.8%. Materials containing 30% glas s desired between shrinking 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!