Why do plastic preforms have scratches and how to deal with them?


What are the advantages of plastic preforms, which are […]

What are the advantages of plastic preforms, which are usually used in packaging, such as medical bottles, cosmetic bottles, and beverage bottles that we see in our lives. The production process of this kind of plastic preform is very complicated. If there is an error in the middle link, various problems may occur, such as scratches and cracks. Then, Haohao mould will explain to you the reasons for the scratches and the precautions.

First. Reasons for scratches on plastic preforms

1. After the injection mold is opened, damage may occur due to a little residual temperature, and scratches may appear.

2. It may also be bumped during transportation, which is also one of the reasons for scratches.

3. Scratches may be caused by the extrusion process during blow molding.

4. When using the product, if you are not careful, it may cause damage. Like the cola we often drink, there is a high probability of scratches when packaging.

Second. Precautions for injection molding

1. Before injection, the material needs to be dried for three or four hours to prevent the moisture in the pet from exceeding the limit and affecting the quality of the product.

2. The injection molding machine template and mold will need to be separated by a heat insulation board. There should be enough exhaust when injection molding to prevent cracking.

3. The melt temperature is controlled at 270-295°C, and the air injection method can be used for measurement during injection molding.

4. Be fast when injecting, and control the time within four seconds.

5. The back pressure is lower than 100bar to prevent wear problems during injection molding.

6. ​​The residence time should not be too long. Usually, if the downtime is not more than 15 minutes, only the air injection treatment is required, and the viscosity PE can be used for cleaning.