Before using the newly purchased TPR injection molding machine for the first time, or when it is necessary to replace the product, change the material, change the color or find that the plastic is decomposed in production, the injection molding machine needs to be cleaned or taken out. When cleaning the injection molding machine, a heating barrel is generally used. method. The cleaning material usually uses plastic raw materials. For TPR materials, transitional cleaning materials can be replaced with newly processed materials.
The molding temperature of injection molding TPR In the process of processing TPR molding, whether the temperature setting is accurate is the key to determining the appearance and performance of the product. The following are some suggestions for temperature setting during injection molding TPR. The temperature of the feed zone should be set very low so as not to block the feed port and allow entrained air to escape. In order to improve the mixing state when using the color masterbatch, the temperature of the transition zone should be set above the melting point of the color masterbatch. The temperature of the area closest to the nozzle should be set close to the desired melting temperature. Therefore, after the test, the usual temperature setting range of the injection molded tpr products in each area is: the barrel is 160 to 210 degrees Celsius, and the nozzle is 180 to 230 degrees Celsius.
Generally, the control of injection tpr injection pressure is divided into the control of primary injection pressure, secondary injection pressure (hold pressure) or more than three injection pressures. Whether the timing of pressure switching is appropriate is very important to prevent excessive pressure in the mold, prevent flash or lack of material, etc. The specific volume of the molded product depends on the melt pressure and temperature when the gate is closed during the pressure period.
When switching from the holding pressure to the product cooling phase, if the pressure and temperature are the same each time, the specific volume of the product will not change. At a constant molding temperature, the important parameter that determines the product size is the holding pressure, and the important variables that affect the product size tolerance are the holding pressure and temperature. For example: after filling the mold, the holding pressure will immediately decrease, when the surface layer has a certain thickness, the holding pressure will increase again. In this way, a lower clamping force can be used to form larger thick-walled products, thereby eliminating shrinkage and flashing.
The cooling time mainly depends on the injection molding tpr melt temperature, product wall thickness and cooling efficiency. In addition, the hardness of the injection molded tpr material is also a factor. Compared with very soft varieties, harder varieties cure faster in the mold. If cooling is performed from both sides, the cooling time required per 0.100 inch of wall thickness is usually about 10 to 15 seconds. Packaged products require longer cooling times because they can be effectively cooled through a smaller surface area.
The above are the precautions for the injection molding tpr process, I hope it will help you.