Thin-wall Injection Molding Machine

Plastic is a polymer organic compound mainly composed of resin. 

Plastic products have the advantages of low density, light weight, good insulation, chemical stability, wear resistance, shock absorption, and good light transmittance, and are widely used in household appliances, communication equipment, daily necessities, etc. At present, China has become a world industrial processing center (production base), especially with series products such as color televisions, mobile phones, air conditioners, refrigerators, washing machines, etc. accounting for 50% of global production. 

These products heavily use plastic parts, which account for 50% to 80% of the total product cost. Therefore, while ensuring product quality, thin-walled parts help to reduce product costs. In addition, mobile phones, laptops, and other devices are developing towards a "light and thin" type, coupled with the widespread use of disposable water cups, bowls, spoons, lunch boxes, etc., which has prompted domestic and foreign researchers to start researching thin-walled technology for plastic parts.

Analysis of the Five Key Points of Thin Wall Technology

1、 Select high fluidity materials

The selection of plastic shell materials is crucial for the formation of products. As the wall thickness decreases, it is necessary to use plastics with better physical properties to maintain product strength. Materials for thin-walled injection molding must have the following characteristics: good flowability, high impact strength, high thermal deformation temperature, good dimensional stability, high heat resistance, good flame retardancy, high mechanical assembly, and appearance Excellent quality and effectiveness. 

And fluidity is particularly important. Once the fluidity of raw materials is poor, improvements can only be made from the equipment, such as increasing material temperature, high-speed and high-pressure, using oil temperature machines or hot runner effects to improve the fluidity of raw materials, in order to produce qualified products.

At present, thin-walled injection molding mainly uses polyolefin materials, such as PP and PE, and PET, PS, PA, ABS, PC, etc. are also applicable.

The important trend of consumer and industrial electronic products is more data transmission and smaller design space. It is necessary to integrate smaller and thinner parts into more compact designs, save assembly space, and adapt to higher power and faster data transmission speeds. Therefore, the requirements for the materials used are also increasing, especially in terms of high temperature resistance and material performance stability.

2、 Product Design

The design philosophy and methods of thin-walled products are complex and further influenced by molding limitations and material selection. The design process should focus on considering the rigidity, impact resistance, and manufacturability of the product.

The design of thin-walled injection molded products should pay special attention to the layout of the injection port, and try to balance the injection as much as possible, so that the filling of the entire product can be balanced. 

In addition, special consideration should be given to the design of exhaust. For some products that are wide and have thin walls, exhaust fins can be used for exhaust. 

Pay attention to the arrangement of exhaust fins as perpendicular as possible to the final convergence line, which can effectively increase exhaust efficiency. For example, the phone battery case, as the thickness of the phone is getting thinner, we also hope to make the thickness of the battery case as thin as possible.

 So, exhaust plates are usually made on the back of the battery shell to effectively discharge the gas from the mold when filling with trapped gas.

Thin walled space structure, also known as shell structure. Its thickness is much smaller than other dimensions (such as span), so it is called thin-walled. It belongs to the spatial force structure, mainly bearing axial pressure within the curved surface, with very small bending moments. Its stress is relatively reasonable, and the material strength can be fully utilized.

Mold materials: 1. Use 2316 and 638 mold blanks to prevent rust on the mold and water holes; 

2. The front and rear molds are made of heat-treated steel materials such as 2344, S136, DC53, GS767, etc., and treated to HRC48-52 to extend the mold life and prevent rust; 

3. Some inserts in the front and rear molds, such as hot nozzle inserts, use S136 or 083 and heat treatment, while the bottom inserts in the front mold cup use S136, 083, 2344 and other heat treatment methods. The low top inserts in the rear mold cup, due to the high temperature near the hot nozzle and poor heat dissipation, use beryllium copper. 

4. Because both the front and rear molds are independent of each other, supports must be added to the guide sleeves on the mold preform.

1. Mold Design: When opening the mold, the front mold should first pop out 0.05-0.1mm to facilitate air blowing and prevent the product from sticking to the front mold;

   2. The fitting surface between the inlay and the columbium must be ground with exhaust grooves, with a specified depth of 0.015mm; 

  3. The water transportation of the entire set of molds should be reasonable and sufficient, with the principle of as much as possible, and each insert should also be fully transported with water; 

  4. Select reasonable mold materials based on product structure, characteristics of raw materials, and quantity of beer. When selecting material sizes, it is important to bear.