What are the common problems of 2K molds in injection molding?

Aug 15, 2022

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What are the common problems of 2K molds in injection molding?

Double Injection Molds 1

Plastic mold toolings are known as the mother of all industries and plays a pivotal role in our daily mass production progress. The mold toolings affect the quality of plastic products, but also they affect their appearance. In fact, the 2K injection mold toolings, because they can be used two different colors and material at the same time, it has a better appearance and it can has more effective working progress,so it is more favored by customers. But due to its process structures are much more complicated than a normal plastic mold, it can cause more problems in the plastic injection molding progress.

Today I would like to show you the normal issues we will meet, what problems will occur in the injection molding of two-color -2K Injection mold toolings?

The first one>

Part deformation : the main reasons for the deformation are as below:

1. There is a large difference in mold temperature between the cav and core half of molds.

2. The plastic parts are sticking in some area which need to reconsider the demoulding.Such as ribs,holes.It can be add some spring move inserts to help the demoulding,the deformation can be solved.

3. The adhesion of the cavity half side is strong.

4. The raw material's switch is abnormal.

5. The switch mode sequence is abnormal.

Two: Material over filling - the reasons for the over filling in the opening of the 2K injection mold are generally:

1. The Insufficient amount of pre-compression in the mold core.

2. The molding condition is not good, also the final finished product is not complete filling after the first shot.

3. The size of the mold kernel is not in place, resulting in insufficient thickness of the finished product.

4. If the second shot is PU, TPE and other soft materials, it may be caused by the material temperature and the mold temperature being too high.

Three: The parting line is obvious - the reasons for the obvious parting line in the opening of the 2K injection mold are generally:

1. The mold has no venting or the venting is too big.

2. The gate position or numbers are not good.

3. The setting parameters are not good.

4. The mold temperature is high enough,please consider to increase the mold temperature and also the injection pressure or speed is low.

No.4: Part cracking :the main reasons for part cracking in the two color or 2K injeciton molds are often to see:

1. If the temperature is too high, the sol will be too soft and lose its toughness, which will make it more prone to embrittlement.

2. The filling speed. Generally, we have to meet the filling requirements of the plastic mold at the right speed.If the speed is too slow to fill,the parts are easy to get crack.

3.Please consider the injection pressure, in the process of 2K injection molding, if the injection pressure is too large and also the injection speed is too quick, the material is too much, the injection holding time is too long, all of these reasons will cause the excessive internal stress and the stress will cause part cracking;

4.The wrong gate position.We will consider to make moldflow analysis when we start to make mold design.

The wrong gate position will cause the filling weld lines,then this weld line will cause part crack easily.

Actually,compared with the other normal molds, the 2K injection mold has a much more complex structure and also request an unique plastic mold machining tolerance.The design should consider the 2K injection machine's data sheet and also it is much more difficult to process during mold making. In the reality, the problems may be far more than the upper we metioned. Therefore, we suggest that our customers should consider carefully when choosing a 2K injection mold supplier.

Contact Deep Mould,you will be satisfied with our professional service and competitive price.