What points should be paid attention to in the design of injection mold?


Author: MULAN -Plastic Molding Manufacturer

Injection mold processing is an essential tool in the industrial production of plastic products. It is generally composed of seven systems: pouring system, guiding system, forming system, core pulling system, ejection system, cooling system and exhaust system. In the production and manufacture of injection molds, the design of injection molds is a very important link. In the design process, it is necessary to comprehensively consider various factors and finally design products that can meet the production needs. Then in the design process of injection molds, there are What points need attention? Next, injection mold processing manufacturers will explain to you! Product wall thickness 1. 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 to be too long, resulting in problems such as shrinkage, and should consider changing the product structure. 2. Uneven wall thickness will cause surface shrinkage. 3. Uneven wall thickness will cause pores and weld marks.

Ribs 1. Reasonable application of ribs can increase product rigidity and reduce deformation. 2. The thickness of the reinforcing rib must be ≤ (0.5~0.7)T product wall thickness, otherwise the surface will shrink. 3. The single-side slope of the reinforcing rib should be greater than 1.5° to avoid top damage.

Rounded corners 1. Too small rounded corners may cause stress concentration of the product, resulting in cracking of the product. 2. If the fillet is too small, it may cause stress concentration in the mold cavity, resulting in cracking of the cavity. 3. Setting reasonable rounded corners can also improve the processing technology of the mold. For example, the cavity can be directly milled with R cutter to avoid low-efficiency electric machining.

4. Different rounded corners may cause the movement of the parting line, and different rounded corners or clear corners should be selected according to the actual situation. Mold opening direction and parting line Each injection molding product must first determine its mold opening direction and parting line at the beginning of the design, so as to ensure that the core-pulling slider mechanism is reduced as much as possible and the parting line is eliminated. The effect of appearance. 1. After the mold opening direction is determined, the product's ribs, buckles, protrusions and other structures are designed to be consistent with the mold opening direction as much as possible, so as to avoid core pulling and reduce stitching lines, prolonging the life of the mold.

2. After the mold opening direction is determined, an appropriate parting line can be selected to avoid undercuts in the mold opening direction to improve appearance and performance. Drafting slope 1. Appropriate drafting slope can avoid product pulling (garbage). The demoulding slope of the smooth surface should be ≥ 0.5 degrees, the surface of the fine grain (sand surface) should be greater than 1 degree, and the surface of the rough grain should be greater than 1.5 degrees.

2. Appropriate demoulding slope can avoid product top damage, such as top whitening, top deformation, and top breaking, which are the basic requirements for injection mold design. 3. The slope of the outer surface should be greater than the slope of the inner surface in the design of deep cavity structure products, so as to ensure that the mold core does not deviate 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 mold opening direction, which can avoid core pulling. 3. When the aspect ratio of the hole is greater than 2, the draft should be set. At this time, the diameter of the hole should be calculated according to the small diameter size (larger entity size).

4. The length-to-diameter ratio of the blind hole is generally not more than 4 to prevent the hole needle from being bent. 5. The distance between the hole and the edge of the product is generally greater than the hole size. The accuracy of injection molded parts is due to the unevenness and uncertainty of the shrinkage rate during injection molding. The precision of injection molded parts is obviously lower than that of metal parts. The dimensional tolerance of mechanical parts cannot be simply applied. Appropriate tolerance requirements should be selected according to the standard. my country also released it in 1993. According to GB/T14486-93 "Dimensional Tolerance of Engineering Plastic Molded Plastic Parts", the designer can determine the dimensional tolerance of the part according to the requirements of the plastic raw materials used and the use requirements of the part according to the regulations in the standard.

At the same time, it is necessary to determine the appropriate design tolerance accuracy based on the comprehensive strength of the factory and the design accuracy of peer products. The deformation of injection molded parts improves the rigidity of the injection molded product structure and reduces the deformation. What are the basic points of injection mold design? What are the basic points of mold design? Set reasonable stiffeners.

Buckle 1. The buckle device is designed to be shared by multiple buckles at the same time, so that the overall device will not fail to operate due to damage to individual buckles, thereby increasing its service life, and adding rounded corners to increase strength. . 2. The tolerance requirements for the relevant dimensions of the buckle are very strict. If there are too many undercut positions, it will easily cause damage to the buckle; on the contrary, if there are too few undercut positions, it will be difficult to control the assembly position or the combination part will be too loose. The solution is to reserve a way to modify the mold and add glue easily.

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