Is it necessary to open the mold for plastic injection molding?

Update:07-08-2020
Summary:

Is it necessary to open the mold for plastic injection […]

Is it necessary to open the mold for plastic injection molding?

The mold must be opened before injection can be performed. However, some factories with public molds can directly inject injection without opening the mold, but it may not be suitable.

The specific items that need to be clarified before opening the plastic mold are as follows:

For example, what materials are used?

Which supplier supplies the materials?

Different suppliers of the same material will shrink differently. What are the requirements for parting lines?

What degree of appearance should be achieved?

Do you want to etch?

Plastic furniture mould

Or polishing?

If you want post-processing, such as spraying, plastic mold opening, these are all considerations.

If the above problems are clear, what are the matters needing attention when opening plastic molds:

1. The shrinkage coefficient of each material is different, and the plastic mold must have a reasonable shrinkage rate.

2. The plastic mold must have sufficient rigidity, otherwise it will deform when the mold is clamped and held, causing "flash".

3. If the product is ejected while opening the mold, the ejector page of the injection molding machine can be set (but some injection molding machines do not have this function)

4. Choose a reasonable demoulding method, choose a reasonable position and quantity of ejector pins, to ensure that the product is not damaged during ejection.

5. The cooling (water passage) in the plastic mold is related to the product size, shape, plastic properties, and pressure holding time.

6. The plastic mold should choose a reasonable exhaust position and its volume control. Otherwise, plastic injection will be dissatisfied and the product will be "short of material".

7. The fixing method of the plastic mold and the injection molding machine should be reasonable, reliable and firm to prevent accidents caused by displacement when the mold is closed. And to be easy to disassemble.

8. The plastic mold moves with the injection molding machine together with the movable mold part without the return spring. The mold ejector plate and the machine ejector rod are connected together (commonly known as strong top).

9. The injection channel should be selected reasonably, so that the material can reach each place evenly (the flow path is equal), and there should be sufficient storage to ensure that the plastic is supplied with the plastic during the shrinking process.

10. Post-processing of plastic mold materials is not required, because: the plastic is soft and does not require special requirements such as hardness, and the heat treatment process may cause mold deformation.

11. The roughness level in the cavity of the plastic mold must reach the "mirror level", otherwise the product will be difficult to demold, and the product will be damaged due to excessive force when ejecting. The roughness of positioning pins, clamping surfaces and other parts are all regulated by standards.