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What should be paid attention to in the design of injection mold
Product wall thickness
1. All kinds of plastics have a certain range of wall thickness, generally 0.5-4mm. When the wall thickness exceeds 4mm, the cooling time will be too long, resulting in problems such as shrink printing, etc., so the product structure should be changed.
2. Uneven wall thickness will cause surface shrinkage.
3. Uneven wall thickness will cause porosity and weld mark.
1. The reasonable application of stiffeners can increase the rigidity of products and reduce the deformation.
2. The thickness of stiffener must be ≤ (0.5-0.7) t product wall thickness, otherwise the surface will shrink.
3. The single side slope of stiffener shall be greater than 1.5 ° to avoid top injury.
1. Too small fillet may cause product stress concentration and product cracking.
2. Too small fillet may cause stress concentration in the mold cavity and cause cavity cracking.
3. Setting a reasonable fillet can also improve the processing technology of the mold. For example, the cavity can be directly milled with r-knife to avoid low efficiency electrical machining.
4. Different fillets may cause the movement of parting line. It is necessary to select the basic points of different fillets or angle cleaning injection mold design according to the actual situation.
Opening direction and parting line
At the beginning of each injection molding product design (Shanghai mold design training school), the mold opening direction and parting line shall be determined to ensure to minimize the core pulling slider mechanism and eliminate the impact of parting line on the appearance.
1. After the opening direction is determined, the stiffener, buckle, bulge and other structures of the product shall be designed to be consistent with the opening direction as far as possible, so as to avoid core pulling to reduce the seam line and extend the service life of the mold.
2. After the mold opening direction is determined, the appropriate parting line can be selected to avoid reverse buckle in the mold opening direction, so as to improve the appearance and performance. Shanghai mold design training
Ejection gradient
1. Proper demoulding slope can avoid product galling (scuffing). The demoulding slope of smooth surface shall be ≥ 0.5 degree, that of fine grain (sand surface) surface shall be greater than 1 degree, and that of coarse grain surface shall be greater than 1.5 degree.
2. Proper demoulding slope can avoid top damage of products, such as top white, top deformation, and the basic requirements of top break injection mold design.
3. In the design of deep cavity structure products, the inclination of the outer surface shall be greater than that of the inner surface as far as possible to ensure that the mold core does not deviate during injection molding, to obtain uniform product wall thickness, and to ensure the material strength of the product opening.
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 opening direction, so core pulling can be avoided.
3. When the length diameter ratio of the hole is greater than 2, the demoulding slope shall be set. In this case, the diameter of the hole shall be calculated according to the minor diameter (maximum solid size).
4. The length diameter ratio of blind hole is generally no more than 4. Punching and bending of anti hole needle
5. The distance between the hole and the edge of the product is generally greater than the hole size.
The mould over door laundry hanger,Hand Cleaning Towel Bucket,baby wipes case cover,Baby Wipe Dispenser have accurate ejection gradient,if not, product will not be complete.
Precision of injection parts
Due to the non-uniformity and uncertainty of shrinkage during injection molding, the accuracy of injection molded parts is significantly lower than that of metal parts, so the dimensional tolerance of mechanical parts that cannot be simply applied should be selected according to the standard. China also issued GB / t14486-93 in 1993.
According to the dimensional tolerance of engineering plastic molded parts, the designer can determine the dimensional tolerance of the parts according to the requirements of the plastic raw materials and parts.
At the same time, according to the comprehensive strength of the factory and the design accuracy of the products of the same industry, the appropriate design tolerance accuracy should be determined.
Deformation of injection parts
In order to improve the rigidity of the injection product structure and reduce the deformation of the injection mold, the basic points of the mold design are to avoid the flat structure as much as possible, and reasonably set the flanging and concave convex structure. Set up reasonable stiffeners.
Buckle position
1. The buckle device is designed to share multiple buckle positions at the same time, so that the whole device will not be unable to operate due to the damage of individual buckle positions, so as to increase its service life. In addition, multiple filters and fillets are added to increase the strength.
The tolerance requirements of the relevant dimensions of the buckle position are very strict, and too many buckles are easy to cause damage to the buckle position; on the contrary, too few buckles are difficult to control the assembly position or the assembly part is too loose. The solution is to reserve a way to change the mold and easily add glue.
What are the factors that affect the design of injection mold
Parting surface, that is, the contact surface where the concave and the convex fit each other when the injection mold is closed, its position and form are determined by the factors such as the shape and appearance of the product, the wall thickness, the forming method, the post-processing technology, the mold type and structure, the demoulding method and the structure of the molding machine.
2. Structural parts, i.e. slide block, inclined top, straight top block, etc. of complex mold, the design of structural parts is very critical, which is related to the life, processing cycle, cost, product quality, etc. of the mold. Therefore, the design of complex mold core structure requires high comprehensive ability of the designer, and it is possible to pursue a simpler, more durable and more economic design scheme.
3. Mold accuracy, i.e. card avoidance, precise positioning, guide post, positioning pin, etc. The positioning system is related to the product appearance quality, mold quality and service life. According to the different mold structure, different positioning methods are selected. The positioning accuracy control mainly depends on the processing. The internal mold positioning is mainly considered by the designer to design a more reasonable and easy to adjust positioning method.
4. Pouring system, that is, the feeding channel from the injection machine nozzle to the cavity, including the main flow channel, shunt channel, gate and cold cavity. In particular, the location of the gate should be selected to facilitate the molten plastic to fill the mold cavity in a good flow state, and the solid flow channel attached to the product and the gate cold material can be easily ejected from the mold and removed when the mold is opened.
5. Plastic shrinkage and various factors affecting the accuracy of injection mold, such as mold manufacturing and assembly errors, mold wear, etc. In my experience, mould of over door laundry hanger,Hand Cleaning Towel Bucket,baby wipes case cover,Baby Wipe Dispenser should pay attention to this question.




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