What Should We Avoid When Product Injection Pail Mould
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1. Die opening direction and parting line
At the beginning of the design of each injection moulding product, the mould opening direction and parting line should be determined first, so as to minimize the core-pulling slider mechanism and eliminate the influence of parting line on appearance.
1. After the Pail Mould opening direction is determined, the stiffeners, buckles and bumps of the product shall be designed to be consistent with the mould opening direction as far as possible, so as to avoid core-pulling to reduce the stitching line and extend the life of the mould.
2. After the die opening direction is determined, appropriate parting line can be selected to avoid the reversal of the die opening direction, so as to improve the appearance and performance.
2. Demoulding slope
1, the appropriate demoulding Angle can avoid the product drawing (drawing). Release slope of smooth surface shall be ≥0.5 degree, fine grain (sand surface) surface shall be greater than 1 degree, and coarse grain surface shall be greater than 1.5 degree.
2. Proper demultifying Angle can avoid top injury, such as top white, top deformation and top breakage.
3. In the design of deep cavity structure products, the slope of the outer surface should be greater than that of the inner surface as far as possible, so as to ensure that the mould core is not off-center during injection moulding, obtain uniform product wall thickness, and ensure the material strength of the product opening.
3. Product wall thickness
1, all kinds of plastics have a certain range of wall thickness, generally 0.5 ~ 4mm, when the wall thickness of more than 4mm, will cause cooling time is too long, shrinkage and other problems, should be considered to change the product structure.
2. Uneven wall thickness will cause surface shrinkage.
3. Uneven wall thickness will cause pores and weld marks.
4. Strengthen tendon
1. Reasonable application of reinforcement can increase product rigidity and reduce deformation.
2. The thickness of reinforcement must be ≤ (0.5 ~ 0.7) T product wall thickness, or it will cause surface shrinkage.
3. The single side slope of the stiffener should be greater than 1.5° to avoid top injury.
5. The rounded corners
1. Round corners too small may cause product stress concentration, resulting in product cracking.
2. Round corners too small may cause mould cavity stress concentration, resulting in cavity cracking.
3. Set reasonable corners, can also improve the mould processing technology, such as cavity can be directly using R cutter milling processing, and avoid low efficiency of electrical processing.
4. Different rounded corners may cause the parting line to move, so different rounded corners or clear corners should be selected based on the actual situation.
6. Hole
1, the shape of the hole should be as simple as possible, generally take the round.
2. The axial direction of the hole is consistent with the mould opening direction, which can avoid core-pulling.
3. When the length-diameter ratio of the hole is greater than 2, the demoulding slope should be set. The diameter of the hole should be calculated according to the small diameter size (maximum solid size).
4. The length-diameter ratio of blind hole is generally not more than 4. Anti-hole needle punch bending
5. The distance between the hole and the edge of the product is generally larger than the aperture size.
7. The injection mould core pulling, sliding block mechanism and avoid
1, when the plastic parts according to the direction of mould opening can not be successful demoulding, should design core-pulling slider mechanism. The sliding block of core-pulling mechanism can shape complex product structure, but it is easy to cause defects such as stitching and shrinkage, increase the cost of the mould and shorten the life of the mould.
2. When designing injection moulding products, avoid core-pulling structure if there is no special requirement. For example, the hole axial direction and the rib direction are changed to the die opening direction, and the cavity core is used to bump through and so on.
8. Integrated hinge
1. The toughness of PP material can be used to design the hinge into one with the product.
2. The size of the film as the hinge should be less than 0.5mm and keep even.
3. injection moulding integrated hinge, gate can only be designed in one side of the hinge.
9. Insert
1. Insert inserts in injection products to increase local strength, hardness, dimensional accuracy and set small threaded holes (shafts) to meet various special needs. It also increases the cost of the product.
2. The inserts are usually copper, but they can also be other metals or plastic parts.
3. The insert part in the embedded plastic shall be designed with anti-rotation and anti-pull structure. Such as: knurling, holes, bending, flattening, shaft shoulder, etc.
4, insert around the plastic should be appropriately
thick, in order to prevent the plastic stress cracking.
5. When designing the insert, the positioning method (hole, pin, magnetic) in the mould shall be fully considered.
10. identifying
Generally, the product logo is set on the flat surface of the product and adopts the convex form. Select the surface where the normal direction and the die opening direction ruler may be the same to set the logo to avoid strain.
11. Precision of injection parts
Due to the inhomogeneity and uncertainty of shrinkage rate in injection moulding, the precision of injection parts is obviously lower than that of metal parts, so the dimensional tolerance of mechanical parts cannot be simply applied, and appropriate tolerance requirements should be selected according to the standard. China also issued in 1993 GB/T14486-93 "Engineering Plastic moulding plastic Parts Dimensional tolerance", the designer can be used according to the plastic raw materials and the use of the parts, according to the provisions in the standard to determine the size of the parts tolerance. At the same time, according to the comprehensive strength of the factory, the product design precision to determine the appropriate design tolerance precision.
12. Deformation of injection parts
Improve the rigidity of injection product structure and reduce deformation. Avoid flat plate structure as far as possible, set flanging and concave-convex structure reasonably. Set up reasonable reinforcing bars.
13. Buckle position
1. The buckle device is designed to be Shared by multiple buckles at the same time, so that the whole device will not fail to operate due to the damage of individual buckles, so as to increase its service life. In addition, it is required to add more filaments and rounded corners to increase its strength.
2. The tolerance requirements of the relevant dimensions of buckle position are very strict, and too many reverse position is easy to cause the buckle position damage; On the contrary, if the reverse position is too little, the assembly position is difficult to control or the assembly part is too loose. The solution is to reserve the mould easy to add glue way to achieve.
14. Welding (hot plate welding, ultrasonic welding, vibration welding)
1. Welding can improve the connection strength.
2. Welding can simplify product design.
15. The contradiction between process and product performance should be considered reasonably
1. The contradiction between appearance, performance and process must be considered comprehensively when designing injection moulding products. Sometimes a good look or performance can be achieved at the expense of part of the craft.
2. structural design can not avoid the injectionPlastic Bucket Mould defects, as far as possible to make the defects occur in the hidden parts of the product.
16. BOSS design principles:
1) the pillar as far as possible not to be used alone, should be connected to the outer wall or with the reinforcement used, the purpose is to strengthen the strength of the pillar and make the flow of rubber more smooth.
2) the height of the prop is generally not more than two and a half times the diameter of the prop. Too high a prop will cause air trapping in plastic parts when forming (too long will cause air holes, burning, insufficient filling, etc.).
3) if the height of the pillar is more than two and a half times the diameter of the pillar, especially away from the outer wall of the pillar, the strength of the way to strengthen the pillar is to use reinforcement bars
4) The BOSS shape is mainly round, while other shapes are not easy to be processed
5) The position of the BOSS should not be too close to the corner or the outer wall. It should be kept a distance from the outer wall of the product
6) Some thickness can be removed around the BOSS (i.e., opening the crater) to prevent shrinkage and subsidence
7) BOSS's dialing Angle: usually 0.5° outside, 0.5° inside or 1