Back pressure action of vertical injection molding machine

Date:2020-04-02 Author:小花 Click:

Vertical injection molding machine back pressure has a variety of functions, should be controlled in the appropriate range. If the back pressure is too high, it will first cause the high temperature and poor viscosity of the melt plastic, which is not conducive to the full plasticization of the melt. Some melt/colorant with poor thermal stability will even decompose at high temperature, resulting in large color difference and uneven coloring when plastic parts are formed; Second, the back pressure is large, the screw return speed of small vertical injection molding machine is slow, the feeding time is prolonged, which affects the production efficiency; Three is melting at high pressure, the material will salivate at the nozzle, leading to nozzle blockage, otherwise the next injection will produce cold points. Finally, the back pressure is too high, the load of the screw mechanism increases, and the wear intensifies. 立式注塑机背压作用

Let's take a look at the specific role of vertical injection molding machine back pressure.

1, prevent back wire, melt fully plasticize, ensure that toner, master batch, melt fully mixed, avoid plastic molding color difference or even color mixing;

2. Compress the gas inside the molten plastic, reduce the bubbles on the surface and inside the bubbles of plastic products, and improve the luster uniformity of plastic;

3. The plastics in the melt will be enriched, the density will increase, and then the injection volume will increase. In addition, the uniform melt will ensure the stability of the weight and size of plastic parts;

4. Increase the humidity of the plastic melt, improve the flow of the filling mold, and avoid cold particles on the surface;

5. The increase of back pressure can also improve the operation and surface shrinkage of plastic products.

Injection molding machine back pressure also has a negative effect, its role can not be reflected, the molten material is not fully plasticized, small density, forming size and weight fluctuations, easy to produce color mixing, poor overall luster, serious is the bubble, bubble, cold particles.