Have You Solved These Problems Encountered in The Production Process of TPE Extrusion Materials?

In the production process of TPE products, there are always some troublesome problems when using the extrusion process:

1. Rough surface of molded product

The surface of the molded product is not smooth and is rough (pitted), which is usually caused by poor plasticization.

(1) As a countermeasure, it is of course necessary to select an appropriate molding machine;

(2) However, it is also very important to optimize the molding conditions such as setting temperature, screw speed, and filter type;

(3) In addition, the use of high temperature and fine mesh (filter) can also improve plasticization efficiency;

(4) Some grades of thermoplastic elastomers (TPE) contain a large amount of hygroscopic components or fillers, so it is very necessary to dry them before molding;

(5) If molding is performed without drying, problems such as foaming and surface roughness will occur.

2. Scaling

Scaling is the deposit accumulated on the edge of the die during extrusion molding. Some of its components come from the extruded material, while others come from special additives.

(1) As a countermeasure, reducing the amount of lubricant can effectively improve the material properties, because when the lubricant is added in excess, the lubricant itself is one of the factors that cause scaling;

(2) The use of Teflon coating on the die can also reduce the generation of scaling;

(3) In addition, the use of damp materials should be avoided.

3. Unstable extrusion volume

Fluctuation of extrusion volume is an unstable phenomenon. The fluctuation of melting point at the feeding part or compression part of the screw is the main reason for instability. The size and cycle of extrusion fluctuation are irregular. These phenomena can be considered to be caused by the shape of the screw and the extrusion conditions not being suitable for the material. Therefore, it is necessary to adjust the extrusion conditions and replace the screw with a different shape.

When the extruder temperature fluctuates greatly, the unstable fluidity of the material in the extruder is also one of the reasons for this problem. In addition, the slippage of the screw and the pellets at the feeding part will also cause the extrusion to be unstable. While using a bucket dryer to preheat the pellets, it can be improved by increasing the temperature of the barrel under the hopper.

4. Deformation

TPE extrusion molding is usually extruded from a die and cooled in a water tank. If the molded product cannot be cooled uniformly at this time, it is very easy to deform.

Especially for molded products with complex shapes and high dimensional accuracy, it is very necessary to use cooling calibration or detection equipment. In addition, during the multi-layer extrusion process, deformation is also very easy to occur due to the different shrinkage rates of the combined materials.

5. Stripes

Extruded products may sometimes have streaks or marks on the same part. In this case, you can do the following:

(1) It is necessary to check or confirm whether there are any signs of damage, dirt, scale, etc. on the die;

(2) Failure to clean or eliminate the material properly when changing materials is also one of the reasons for this problem;

(3) Poor melting of materials at the junction of the die can also easily cause streaks.

For common production and processing anomalies, you can first perform the following operations:

(1) Most of the abnormalities can be checked and adjusted in equipment (parts) processing;

(2) They can be eliminated by adjusting process parameters;

(3) Some abnormalities can also be solved from the perspective of TPE raw materials.

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