Features of plastic parts

1, cost-effective, cheap, compared with other materials such as metal and glass cost is much lower.

2, with good corrosion resistance, can be used to make food boxes and various tableware, will not pollute the food, will not be dissolved by the acid and alkali in the food;

3, relatively light, especially polyurethane products with strong elasticity and impact;

4, widely used, can make almost any item, can meet the various needs of consumers;

5, processability and formability is also very strong, according to customer needs, the raw materials can be heated into various shapes;

6, anti-aging ability and anti-weathering ability are very strong, can maintain a long service life in the outdoor;

7, the heat insulation is very good, can effectively alleviate the indoor and outdoor heat exchange, play a role in heat insulation;

8, good durability, can be used for a long time without interruption, and maintain quality.

9, excellent electrical insulation performance, plastic parts are bad conductors of electricity, its surface resistance, volume resistance is very large, breakdown voltage is large, dielectric loss Angle tangent value is very small.

10, the mechanical strength is widely distributed and high specific strength, because the proportion of plastic parts is small, the strength is large, so it has a high specific strength.

The process of plastic parts processing

1. Ingredients

It requires raw materials in addition to polymers, but also to add some stabilizers, plasticizers, colorants and other plastic additives, so that the use of processed plastic parts will be greatly improved, but also reduce production costs. The polymer is mixed with the additive and dispersed into a dry mix. It can also be processed into pellets.

2. Forming

This is the most critical step in the plastic parts processing process, we want to make various forms of plastic into the desired shape of the embryo. There are many methods for this molding, and the choice is mainly based on the type of plastic, the initial shape and the size and shape of the product. If it is thermoplastic, it is generally used in extrusion, injection molding, calendering, blow molding and thermoforming; If it is a thermosetting plastic, then it can be molded, transfer molding, or injection molding. In addition, there are also casting with liquid monomers or polymers as raw materials.

3, mechanical processing

This step can be seen as an auxiliary process of molding. It can borrow the processing method of metal or wood to make some plastic zero grade with precise dimensions or a small number. The tools and cutting speed used in machining should be in line with the characteristics of plastics.

4. Bonding

This step is to join the plastic parts together, and the methods are mainly welding and bonding. Welding methods are mainly hot air welding, hot melt welding, high frequency welding, friction welding, ultrasonic welding and so on. The bonding method is done using adhesives, such as flux, resin solution and hot melt adhesive bonding.

5. Embellishment

The purpose of this step is to beautify the surface of plastic parts, generally through mechanical modification, that is, grinding, filing, polishing, etc.; Then there is coating, such as coating the surface of the product with paint, and covering the surface of the product with a patterned film

6. Assembly

This is the last step in the processing of plastic parts, that is, the processing of individual plastic parts together into a complete plastic part. And we Guangzhou OTEM Engineering Plastics Co., Ltd. has more than 20 years of plastic parts processing experience, has a solid production plant, professional production equipment, quality assurance, is a good choice.

How to avoid injection defects when processing plastic parts

1. Opening direction and parting line

Each plastic part must first determine its opening direction and parting line at the beginning of the design to ensure that the core pulling mechanism is reduced as much as possible and the parting line is eliminated. After the mold opening direction is determined, the structure of the product reinforcement, fastener, bulge and so on is designed as much as possible to be consistent with the mold opening direction, in order to avoid core-pulling to reduce the stitching line and extend the life of the mold.

2, stripping inclination

Proper release slope can avoid product hair, can avoid product jacking, deep cavity structure product design requirements of the outer surface slope is less than the inner surface slope, to ensure that the mold core is not offset during injection molding, uniform product wall thickness, and ensure the product opening part of the material density strength.

3, product wall thickness

All kinds of plastics have a certain wall thickness range, generally 0.5 ~ 4mm, when the wall thickness exceeds 4mm, it will cause the cooling time is too long, resulting in shrinkage and other problems, should consider changing the product structure.

4. Strengthen the tendon

The reasonable application of reinforcing bars can increase the rigidity of products and reduce deformation. The thickness of the reinforcing bar must be less than 1/3 of the wall thickness of the product, otherwise it will cause surface shrinkage. The slope of the single side of the stiffener should be greater than 1.5¡ã to avoid jacking injury.

5. Round the corners

Setting a reasonable rounded corner can also improve the processing technology of the mold, such as the cavity can be directly milled with R knife, and avoid inefficient electrical processing. Different rounded corners may cause the movement of the parting line, and different rounded or clear corners should be selected according to the actual situation.

6. Holes

The shape of the hole should be as simple as possible, generally round. The axial direction of the hole is consistent with the opening direction, which can avoid pulling the core. When the length-diameter ratio of the hole is greater than 2, the demoulding slope should be set. At this time, the diameter of the hole should be calculated according to the small path size (maximum physical size). The aspect ratio of the blind hole is generally not more than 4. The distance between the hole and the edge of the product is generally greater than the aperture size.

7, injection mold core pulling mechanism and avoid

When the plastic parts can not release smoothly according to the direction of the mold, the core pulling mechanism should be designed. The core pulling mechanism can form complex product structure, but it is easy to cause defects such as stitching line and reducing printing, and increase the cost of the mold and shorten the life of the mold. When designing plastic parts, if there are no special requirements, try to avoid the core pulling structure. For example, the axial direction of the hole and the direction of the bar are changed to the direction of the opening mold, and the cavity core is impinged.

8, one hinge

Using the toughness of PP material, the hinge can be designed to be integrated with the product. The size of the film used as the hinge should be less than 0.5mm and remain uniform, and the gate can only be designed on one side of the hinge when the integrated hinge is injected.

9. Insert

Inserts into plastic parts can increase local strength, hardness, dimensional accuracy and set small threaded holes (shafts) to meet a variety of special needs. The part of the insert in the embedded plastic shall be designed with a rotating and anti-pulling structure. The plastic around the insert should be properly thickened to prevent stress cracking of the plastic part. When designing the insert, its positioning mode in the mold (hole, pin, magnetic) should be fully considered.

10. Logo

The product identification is generally set on the flat inner surface of the product and adopts the convex form. The identification can be set on the surface where the normal direction and the square ruler of the open mold may be consistent to avoid strain.

11. Precision of injection parts

Due to the non-uniformity and uncertainty of the shrinkage rate during injection molding, the accuracy of the injection parts is significantly lower than that of the metal parts, and the appropriate tolerance requirements should be selected according to the standard

12, the deformation of injection parts

Improve the rigidity of injection molding product structure and reduce deformation. Try to avoid flat structure, reasonable set flanging, concave and convex structure. Set up reasonable reinforcement.

13. Gas-assisted injection molding

The use of gas-assisted injection molding can improve product rigidity, reduce deformation, avoid shrinkage, save raw materials, and shorten cooling time.

14, welding (hot plate welding, ultrasonic welding, vibration welding)

The use of welding can improve the joint strength and simplify the product design.