The use of TPE raw materials can be seen everywhere in life, such as daily necessities, children's toys, etc. TPE raw materials are a kind of green and nontoxic materials, and also belong to a multi-purpose material, and one of the molding processes of TPE raw materials is injection molding process. Let's talk about the injection molding techniques of TPE raw materials.
1, try to use low temperature injection molding.
On the premise of ensuring the plasticizing quality of TPE raw materials, the extrusion temperature is reduced as much as possible, and the melt viscosity is reduced by increasing the injection pressure and screw speed, so as to improve the fluidity. When the material strip injected from the nozzle has smooth surface and bright light, it can be known that the plasticizing quality is good. If the strip injected from the nozzle is bright, it can be known that the barrel temperature can also be lowered. As far as possible, low temperature injection molding can reduce the cooling time, thus improving the production efficiency of customers.
2. Keep the packing pressure as small as possible.
Generally, the holding pressure is smaller than the injection pressure, and the holding time can be selected by weighing the product, which is based on the weight of TPE raw material not increasing, or the shrinkage mark accepted by the customer. If it is found that the gate is easy to break during demoulding, and the second trick can't work, it should be feasible to reduce the holding pressure.
3. If the surface of TPE raw material is strict, it must be dried before injection molding.
Generally, it is hopper drying at 70~80℃/2h or tray drying at 80~100℃/1h. For tray drying, it should be noted that the material layer thickness is generally not more than 50 mm. Tray drying is recommended. If there are bubbles on the surface of the injection-molded material strip, or if the material strip is cut and holes are found in it, or scattered silver wire is found on the surface of the product, it can be confirmed that the TPE raw material contains too much water.
4. If it is a multi-stage injection, the speed will change from slow to fast.
Because of this, the gas inside the mold is easily exhausted. If the TPE raw material is covered with gas (bulged inside) or dented, it will be ineffective with the second trick, so it can be adjusted by this method.
5. Upper parabola temperature setting.
The temperature in the middle area of screw is very high, the feeding section is slightly lower, and the nozzle is slightly lower. Typical temperature settings are 150~170℃ (feeding), 170~180℃ (middle), 190~200℃ (front) and 180℃ (nozzle). This temperature setting is only used as reference data, and the specific temperature can be appropriately adjusted according to the specific physical properties of different TPE raw materials. If it is found that the content of TPE raw material bulges (gas is wrapped in it), and the gate is easy to break during demoulding, adjustment can be made with reference to Tip 2.
Through the above techniques of injection molding of TPE raw materials, you can better help you to complete the injection molding of TPE raw materials, thus obtaining a TPE product with very good appearance and quality.
