A, opening direction and parting line

Each injection molding product in the beginning of the design must first determine its opening direction and parting line, to ensure that as much as possible to reduce the core pulling slider mechanism and eliminate the parting line on the appearance of the influence.

1, after the direction of the opening mold is determined, the structure of the product, such as reinforcement, clasps, and protrusions, is designed as much as possible to be consistent with the direction of the opening mold, in order to avoid the core withdrawal to reduce the stitching line and extend the life of the mold.

2, after the direction of the mold is determined, the appropriate parting line can be selected to avoid the reverse buckle in the direction of the mold opening to improve the appearance and performance.

Two, the demoulding inclination

1, the appropriate demoulding inclination can avoid the product hair (stretch). The release slope of the smooth surface should be ≥ 0.5 degrees, fine grain (sand) surface is greater than 1 degree, coarse grain surface is greater than 1.5 degrees.

2, the appropriate demoulding slope can avoid product top damage, such as top white, top deformation, top break.

3, deep cavity structure product design, the external surface inclination should be greater than the internal surface inclination, to ensure that the mold core is not biased during injection molding, to obtain uniform product wall thickness, and to ensure the material strength of the product opening part.

Three, the 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, it will cause the cooling time is too long, resulting in shrinkage and other problems, should consider changing the product structure.

2, uneven wall thickness will cause surface shrinkage.

3, uneven wall thickness will cause porosity and weld marks.

Four, reinforcing bar

1, the reasonable application of reinforcing bar, can increase the rigidity of the product, reduce deformation.

2, the thickness of the reinforcement bar must ≤ (0.5 ~ 0.7)T product wall thickness, otherwise cause surface shrinkage. 3, the slope of the single side of the reinforcement should be greater than 1.5° , to avoid top injury.

Five, rounded corner

1, rounded corner is too small may cause product stress concentration, resulting in product cracking. 2, the rounded corner is too small may cause the mold cavity stress concentration, resulting in cavity cracking.

2, set 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.

3, different corners may cause the parting line to move, should be combined with the actual situation to choose different corners or clear corners.

Six, hole

1, the shape of the hole should be as simple as possible, generally take a circle. 2. The axial direction of the hole is the same as that of the opening mold, which can avoid pulling the core.

2, 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 path size (maximum solid size).

3, the length to diameter ratio of the blind hole generally does not exceed 4. 5, the distance between the hole and the edge of the product is generally greater than the aperture size.

Seven, injection mold core withdrawal, slider mechanism and avoid

1, when the plastic parts according to the direction of the mold can not be smoothly released, the core withdrawal slider mechanism should be designed. The core pulling mechanism slider can form a complex product structure, but it is easy to cause defects such as product stitching line and shrinkage, and increase the cost of the mold to shorten the life of the mold.

2, when designing injection products, if there are no special requirements, try to avoid the core pulling structure. Such as the direction of the hole axis and reinforcement to open the direction of the mold, the use of cavity core impact and other methods.

Eight, one hinge

1, using the toughness of PP material, the hinge can be designed into one product. 2, as the hinge film size should be less than 0.5mm, and maintain uniform, 3, injection hinge, gate can only be designed in a certain side of the hinge.

Nine, insert

1, insert in the injection product can increase local strength, hardness, dimensional accuracy and set small thread holes (shafts) to meet various special needs. At the same time, it will increase the cost of products.

2, inserts are generally copper, can also be other metal or plastic parts.

3, the part of the insert in the embedded plastic should be designed to stop the rotation and anti-pull out structure. Such as: knurls, holes, bending, flattening, shaft shoulders, etc. 4, the plastic around the insert should be properly thickened to prevent stress cracking of the plastic parts.

4, the design of inserts, should fully consider its positioning in the mold (hole, pin, magnetic)

Ten, identification

Product identification is generally set on the flat surface of the product, and the use of convex form, choose the normal direction and the direction of the mold ruler may be consistent with the surface set identification, can avoid strain.

11, accuracy of injection parts

Due to the non-uniformity and uncertainty of the shrinkage rate during injection molding, the accuracy of injection parts is significantly lower than that of metal parts, and the dimensional tolerance of mechanical parts can not simply be applied. China also released GB/T14486-93 "Engineering plastic molding plastic parts dimensional tolerance" in 1993, the designer can according to the plastic raw materials used and the use of parts requirements, according to the provisions of the standard to determine the dimensional tolerance of the parts.

Twelve, the deformation of injection molding parts

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

13, buckle

1, the buckle device is designed to share multiple buckle at the same time, so that the overall device will not be damaged by individual buckle and cannot operate, thereby increasing its service life, and then more test filter and rounded corners to increase strength.

2, is the buckle related size tolerance requirements are very strict, too much reverse buckle position is easy to form buckle damage; On the contrary, if the reverse position is too small, the assembly position is difficult to control or the combination part is too loose.

The solution is to reserve the way to change the mold easily add glue to achieve.

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

1, the use of welding, can improve the strength of the connection.

2, the use of welding, can simplify product design.

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