Injection mold design need to pay attention to what points

Injection mold is a necessary tool in the industrial production of plastic products, it is generally composed of gating system,

Injection mold is a necessary tool in the industrial production of plastic products, it is generally composed of gating system, guide system, forming system, core pulling system, ejection system, cooling system and exhaust system, a total of 7 systems, in the production of injection mold in the injection mold design is a very important link, in the design of the link need to take into account the factors of all aspects of the final design of the product to be able to meet the production needs, then in the injection mold design link what points need to pay attention to it?

Product wall thickness 1. Various plastics have a certain wall thickness range, generally 0.5~4mm. When the wall thickness exceeds 4mm, it will cause problems such as too long cooling time and shrinkage. Consideration should be given to changing the product structure.

2, uneven wall thickness will cause surface shrinkage.

3. Uneven wall thickness will cause pores and weld marks.

Reinforcing ribs 1. Reasonable application of reinforcing ribs can increase product rigidity and reduce deformation.

2. The thickness of the reinforcing rib must be less than or equal to (0.5~0.7)T product wall thickness, otherwise the surface will shrink.

3. The single-sided slope of the reinforcing rib should be greater than 1.5 ° to avoid top injury.

Fillet 1, fillet is too small may cause product stress concentration, resulting in product cracking.

2, fillet is too small may cause mold cavity stress concentration, resulting in cavity cracking.

3, set a reasonable fillet, but also can improve the mold processing technology, such as the cavity can be directly used R cutter milling processing, and avoid low efficiency of electrical processing.

4, different rounded corners may cause the movement of the parting line, should be combined with the actual situation to choose different rounded corners or clear angle injection mold design of the basic points of what are the basic points of injection mold design.

Mold opening direction and parting line At the beginning of design, each injection product (Shanghai Mold Design Training School) shall first determine its mold opening direction and parting line to ensure that the core-pulling slider mechanism is reduced as much as possible and the influence of parting line on appearance is eliminated.

1. After the mold opening direction is determined, the reinforcing ribs, buckles, protrusions and other structures of the product are designed to be consistent with the mold opening direction as much as possible to avoid core pulling, reduce stitching, and extend the life of the mold.

2. After the mold opening direction is determined, the appropriate parting line can be selected to avoid the inverted button in the mold opening direction to improve the appearance and performance. Shanghai mold design training demoulding slope 1, proper demoulding slope can avoid product hair (flower). The demoulding angle of the smooth surface shall be ≥ 0.5 degrees, the fine-grained (sand surface) surface shall be greater than 1 degree, and the coarse-grained surface shall be greater than 1.5 degrees.

2. Appropriate demoulding slope can avoid product top damage, such as top white, top deformation, and top breaking the basic requirements of injection mold design.

3. When designing deep cavity structure products, the slope of the outer surface should be greater than the slope of the inner surface as far as possible, so as to ensure that the mold core is not deviated during injection molding, obtain uniform product wall thickness, and ensure the material strength of the product opening.

Hole 1. The shape of the hole should be as simple as possible, generally round.

2. The axial direction of the hole is consistent with the direction of mold opening, which can avoid core pulling.

3. When the aspect 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 diameter size (maximum solid size).

The length-diameter ratio of blind holes is generally not more than 4. The anti-hole needle punches 5. The distance between the hole and the edge of the product is generally greater than the aperture size.

Accuracy of injection molded parts due to the unevenness and uncertainty of the shrinkage rate during injection molding, the accuracy of injection molded parts is significantly lower than that of metal parts, and the dimensional tolerance of mechanical parts cannot be simply applied. The appropriate tolerance requirements should be selected according to the standard. China also issued GB/T14486-93 "Dimensional Tolerance of Molded Plastic Parts of Engineering Plastics" in 1993. Designers can determine the dimensional tolerance of parts according to the requirements of plastic raw materials and parts used and the provisions of the standard.

At the same time, according to the comprehensive strength of the factory, the design accuracy of the products of the same industry to determine the appropriate design tolerance accuracy.

The deformation of injection molded parts improves the rigidity of injection molded product structure and reduces the basic points of deformation injection mold design. What are the mold design to avoid flat plate structure as far as possible, and reasonably set flanging and concave-convex structure. Set up reasonable reinforcing ribs.

Buckle position 1. The buckle position device is designed to be shared by multiple buckles at the same time, so that the overall device will not be unable to operate due to the damage of individual buckles, thereby increasing its service life, and then adding more filters and rounded corners to increase strength.

2. The tolerance requirements for the relevant dimensions of the buckle position are very strict. Too many buckle positions are easy to cause damage to the buckle position. On the contrary, if the number of inverted positions is too small, the assembly position will be difficult to control or the combination part will be too loose. The solution is to reserve the way to change the mold and add glue easily.