What are the reasons for the cracks in blister luminous words? How to deal with it

There are three main reasons for the cracks of blister luminescent words: cracks caused by residual stress, cracks caused by external stress and cracks caused by external environment. The following is a brief introduction to the handling methods of these three situations:

1. Cracks caused by residual stress.

Residual stresses are mainly caused by the following three conditions, namely overfilling, demoulding and metal inserts. As a crack that occurs in the case of overfilling, you can start from the following points:

1. If the crack is mainly near the direct gate, you can consider using the multi-point distribution point gate, side gate and shank gate method.

2. On the premise of ensuring that the resin does not decompose and deteriorate, appropriately increase the temperature of the resin to reduce the melt viscosity, improve the fluidity, and reduce the injection pressure to reduce the stress.

3. Under normal circumstances, it is easy to produce stress when the mold temperature is low, and the temperature should be increased appropriately. However, when the injection rate is high, even if the mold temperature is lower, the stress can be reduced.

4. Stress will also occur if the injection and pressure holding time is too long, so it is better to shorten it appropriately or switch it sequentially.

5. Amorphous resins, such as AS resin, ABS resin, PMMA resin, etc., are more prone to residual stress than crystalline resins such as polyethylene and polyoxymethylene, and should be noted.

2. Cracks caused by external stress.

The external stress here is mainly caused by the stress concentration caused by the unreasonable design, especially at the sharp corners.

3. Cracks caused by the external environment.

Water degradation caused by chemicals, moisture absorption, and excessive use of recycled materials can deteriorate physical properties and cause cracks.

When the demoulding is pushed, due to the small demoulding slope, the mold glue and the punch are rough, the push-out force is too large, and the stress is generated, and sometimes even whitening or cracking around the push-out rod. Just take a closer look at where the crack is occurring to determine the cause.

When making LED blister luminous words, when embedding metal parts while injection molding, it is most likely to produce stress, and it is easy to produce cracks after a period of time, which is extremely harmful. This is mainly due to the large difference in the coefficient of thermal expansion between the metal and the resin, and over time, the stress exceeds the strength of the deteriorating resin material and cracks occur. In order to prevent the resulting cracks, as a rule of thumb, universal polystyrene with wall thickness and outer diameter embedded in the metal is generally not suitable for inserts, which have minimal impact on nylon.

Due to the small coefficient of thermal expansion of glass fiber reinforced resin materials, they are more suitable for inserts. In addition, the LED blister light-emitting word preheats the metal insert before molding, which also has a good effect.

Let's find someone to help you deal with it.