1. Improve stiffness when designing parts

1. Reduce uneven wall thickness and design with equal wall thickness to reduce internal stress and avoid deformation.

2. From a mechanical point of view, the larger the plane, the easier it is to deform. Avoid flat design and make three-dimensional parts.

3. Design micro-arc surfaces for large-area planes.

2. Improve the injection molding process

The prerequisite for high-pressure injection is that the mold is high-precision and the FIT mold is in place, otherwise the product will have defects. Especially for parts priced by weight and quantity, when outsourcing processing, the processing factory will produce low-density parts in order to reduce costs.

3. Glass fiber reinforcement

Using a higher grade of plastic in plastic mold manufacturing can definitely improve the stiffness of plastic products, but this will increase the cost, so the material aspect is mainly never improved. In terms of material cost, low-cost plastic reinforcement is used to solve the problem.

4. Surface coating

Aluminum plating, Cu-Zn plating, and chromium plating on the surface of plastic parts can improve the stiffness and surface hardness of the parts, making them less likely to deform.

5. Distribute the work load

From a design perspective, add more support points to disperse the work load and reduce deformation.

Extended information

PP material molding characteristics

1. Physical properties

PP is a non-toxic, tasteless milky white highly crystalline polymer It is one of the lightest varieties of all plastics and is particularly stable to water. The water absorption rate in water for 14 hours is only 0.01%. The molecular weight is about 80,000 to 150,000, and the formability is good. However, due to the large shrinkage rate, the original wall products are easy to dent, and the surface of the products has good gloss and is easy to color.

2. Mechanical properties

PP has high crystallinity and regular structure, so it has excellent mechanical properties. Its strength, hardness, and elasticity are higher than high-density PE (HDPE). The outstanding feature is the bending fatigue resistance (7×10^7), which can be opened and closed by bending without damage marks. The dry friction coefficient is similar to nylon, but not as good as nylon under oil lubrication.

3. Thermal properties

PP has good heat resistance, with a melting point of 164~170℃, and the products can be sterilized at temperatures above 100℃. It will not deform at 150℃ without being affected by external force. Embrittlement is -35℃, and embrittlement will occur below -35℃.

IV. Chemical stability

PP has good chemical stability. In addition to being corroded by concentrated sulfuric acid and concentrated nitric acid, it is relatively stable to various other chemical reagents, but has low Molecular weight aliphatic hydrocarbons, aromatic hydrocarbons, etc. can soften and swell PP, and the chemical stability increases with the increase in crystallinity. Therefore, PP is suitable for making Russian-Chinese chemical pipelines and accessories, and has good anti-corrosion effect.

Reference source Baidu Encyclopedia-pp material