Key Word: Taili Plastic Machinery; Taili Plastic Machinery-Capacity Improving Expert; Efficient; Stable; Protective Glasses; Yellowing Of Glasses Frame
There are different popular injection molded products every year. In the first half of last year, there was a huge demand for protective glasses in the foreign market. As long as they are available, thereās no worry about selling. The export situation is booming, but Mr. Shi of Shandong is very anxious: other people are earning money. Why are my products always returned? What should we do?
When we went to Mr. Shi's factory, we found that the reason why Mr. Shiās products were returned was very simple, that is, the frames made of soft PVC always turned yellow. It's OK without comparison, but compared with peersā. The problem of yellowing is very serious, so it encountered a large number of returns.
Soft PVC and ordinary hard PVC have a great difference, so the injection molding processes also differ a lot. Generally, attention should be paid attention to the following points:
1. Fluid electrothermal and shear heat
At the first time dealing with PVC products, especially soft PVC products, a lot of debugging technicians may have misunderstandings. In fact, the melting of soft PVC material is composed of two parts: the electric heat from resistance wire and the shear heat from screw rotation. Generally, for soft PVC materials, 1 / 3 of the materials melt due to resistance wire heating, while 2 / 3 of the internal materials melt due to shear heat caused by screw rotation.
2. Clear process direction
For the processing of soft PVC products, especially this transparent frame, we must pay attention to the control of screw speed and back pressure. It is generally required to use special customized screw, the screw speed should not be too fast or too slow, and the screw back pressure is generally controlled at about 1MPa. Therefore, we must pay attention to the cleaning of three small pieces of screw barrel. If there are yellow spots and it is difficult to debug without changing other process conditions, we must pay attention to cleaning the gap of the three small pieces.
3. Raw material process
PVC raw materials must be dried before use, otherwise the moisture and air in the material will have a great impact on the accuracy and performance of the product. Generally, common PVC materials should be dried in 60-80 ā oven for about 2 hours. If the drying time is not in place, traces will be easily left on the surface of the product, which will be confused with yellowing.
We finally came out of Mr. Shi's factory until 11:30 in the evening. It's really gratifying that we can help him solve the problem.
Taili Plastic Machinery always keeps in mind that what a good injection molding machine factory should do is to help improving the capacity and boosting the profits, rather than offer the similar products the customers need. This is also what Taili Plastic Machinery keeps doing.
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