Reminder about problems of injection molding containers

Injection molding is to inject molten plastic into a closed mold with low temperature through a nozzle under high pressure. Thermoplastic and thermosetting plastics can be molded by injection molding, and can be used to make various box type packaging containers, such as various turnover boxes and small boxes. For box type packaging containers, the following aspects shall be considered in the structural design:

1、 Wall thickness of container

1. Thickness: the wall thickness of the container is mainly determined by its use, plastic product type, structure, etc. For different thermoplastic engineering plastics, it is generally considered that the time should not be less than 0.6 mm, and 2~4 mm is usually selected; For other thermosetting materials and plastics, due to their poor liquidity management, the thickness is larger, ranging from 1.6 to 2.5 ram for small pieces to 3.2 to 8 mm for large pieces, not exceeding 10 mm.

2. Uniformity: The uniformity of wall thickness has a great impact on the quality of the container. If the thickness difference is too large, it will cause uneven shrinkage, deformation, cracks and other defects. Therefore, equal thickness structure shall be adopted as far as possible in structural design.

3. Smooth transition: In some containers, some components must have different thicknesses due to structural requirements, such as the turning point of the container, which should be used for smooth transition to avoid sudden changes in cross section.

2、 Increase stiffness

1. Add stiffeners: stiffeners can enhance the strength and stiffness of the container. The basic requirements for the stiffeners are that the number of stiffeners should be large, the wall thickness should be thin, the height should be short, and there should be enough slope. The bottom of the stiffeners should be in an arc transition. The direction of the stiffeners should be consistent with the direction of material flow to improve the toughness of the plastic.

2. Improve the shape: most box containers are rectangular thin-walled pieces, which are easy to deform. Various ways should be taken to strengthen them, and the four side walls of the container should be slightly convex to improve the system stiffness; Banded enhancement on the sidewall; Edge enhancement at the edge of the container.

3. Reasonable support: The bottom area of the box container is large, but the whole box bottom should not be used as the support. Since the bottom of the box is slightly bent, the support should be changed into a line support or a point support. The convex side support (i.e. line support) should raise the foot support (i.e. point support), and the raised height is generally 0.3 ー 0.5 mm.

4. Corner: corner is the intersection of two or three faces. No matter what the shape of the container is, the intersection of all surfaces must be rounded, which can greatly improve the rigidity of the container, improve the filling property of the plastic, disperse the stress and reduce the deformation.

3、 Demoulding angle

In order to facilitate the demoulding of molded parts, proper demoulding slope must be fully considered when designing pressure vessels. Too small demoulding angle makes demoulding difficult and damages the surface of the container; If it is too large, the calculation accuracy of main dimensions will be affected.

The demoulding angle varies with the shape of plastic part, plastic type, mold structure, surface roughness, injection molding method, etc.



About Huizhou Dj Molding Co., Ltd

Dj Mold is a China mold maker of plastic molds- injection mold, die casting moulds, plastic blow molding, rotational molding, medical plastic injection molding, two shot plastic injection molding, insert molding, overmolding, metal injection molding, micro injection molding, powder injection molding, ceramic injection molding, liquid injection molding, husky injection molding, household mold, casting mold, die mold tool, custom molds, china moulds, rapid prototyping tooling, plastic prototyping tooling, punch press tooling, die and tooling for mobile/ cell phone parts, automotive parts, vacuum cleaners, rechargeable tools, telephones, copiers, computers, multimedia speakers, and many other electronic products and household appliances. And also a plastic product manufacturer, mold manufacturer China– plastic parts, plastic water tank, plastic balls, plastic containers, plastic buckle, plastic anchor, plastic hanger, plastic spoon, plastic pipe fitting, plastic tumble, plastic tableware, plastic cups, plastic bottles, plastic tray, plastic cosmetic container, plastic case, plastic food container, plastic chairs, plastic caps, plastic cap closure, plastic tubes, plastic water pipes, plastic knobs, plastic tubing, plastic utility boxes, plastic racks and so on.

Person: James Yuan
Company: Huizhou Dj Molding Company Limited
Add:  LongGang Village,LongXi Town,BoLuo County,HuiZhou City,GuangDong Province, China
Tel: 86-752-6682869
Email: [email protected]


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