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Precautions for thermoplastic elastomers when injection molding!

Release time:

2021/06/05

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There are many processing methods of thermoplastic elastomer TPE materials, such as extrusion, blow molding, salivation, etc., today we want to introduce and share one of the widely used and common processing methods "injection molding process", so what should be paid attention to when injection molding of TPE materials?

First of all, the injection molding machine should be cleaned, there are many customers who encounter the physical properties of the products produced, or some other factors, most of which are because the injection molding machine is not cleaned in place, and there are residues of other materials in the barrel.

Then the molding temperature of the material, in the process of processing, the temperature setting is often the key to determine the appearance and performance of the product, after the TPE manufacturer obtains the TPE material, it is necessary to ask the processing temperature of the material, whether it needs to be baked and other key factors, generally speaking, the molding temperature of the TPE material is 160 °C - 240 °C, but we generally recommend that customers do not exceed 220 °C, and then the specific problem can be solved with the TPE manufacturer.

Then is the mold filling, pressure holding and cooling, in the process of product molding, if the filling performance of the product is not good, the pressure reduction will be too large, the filling time is too long, the filling is not satisfactory and so on, in order to improve the filling performance of the product in molding, it can generally be adjusted by changing the gate position, injection pressure, and the geometry of the part.

Finally, there is the influence of injection molding process conditions, and here are some problems and solutions that arise during injection molding.

1、When the plastic molding is imperfect, it should be that the feeding is not properly adjusted, the material is short or the material is too much, the injection pressure is too low, the injection time is short, the plunger or screw is returned too early, the injection speed is slow, and the material temperature is too low.

2、When there is flash (overflow), it should be caused by too high injection pressure or too fast injection speed, or it may be caused by too large feeding amount and too high barrel or nozzle temperature, and if the mold temperature is too high, the viscosity of the plastic will decrease, and the fluidity will increase, causing flash in the case of smooth touching.

3、When silver lines, bubbles or pores appear, it should be noted that the material temperature should not be too high, too high will easily cause decomposition, the injection pressure can also be small, and the pressure holding time should not be short, so that the melt and the cavity surface are not close; The speed of injection is too fast, so that the molten plastic is decomposed by large shear, resulting in decomposition gas; The injection speed is too slow, and the cavity cannot be filled in time, resulting in insufficient surface density of the product. Insufficient material amount The feeding buffer is too large, the material temperature is too low or the mold temperature is too low, which will affect the flow and molding pressure of the melt, and produce bubbles; When the screw is pre-molded, the back pressure is too low and the rotation speed is too high, so that the screw retreats too quickly, and the air is easy to push to the front of the barrel with the material.

4、When there are dark lines of burning, it should be noted that the temperature of the barrel and nozzle should not be too high, the injection pressure is too high, the injection speed is too fast or the injection cycle is too long

The above is to share with you today about the matters that should be paid attention to when thermoplastic elastomers are injected into molding, and how to solve problems, if there are other common problems about TPE materials want to know or consult, you can go to the official website of Dongguan Guofeng Plastic Industry to leave a message and get in touch with us, or you can call the customer service number of the official website.

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