Item function: drain basket
Basin size: 170*180*95mm
Basin weight: 60g
Raw material: PP
Mould material: S136
Mould base: LKM
Injection system: central gate
Ejection system: stripper
Surface treatment: high polishing
Lead time: 50 working days
For designing washing vegetable double-layer basin plastic mould, there are many points that need to be concerned about.
Mould opening direction and parting line
Each injection moulding product must first determine its mould opening direction and parting line at the beginning of design to ensure that the core slider mechanism is minimized and the influence of the parting line on the appearance is eliminated.
After injection moulding opening direction is determined, reinforcement ribs, buckles, protrusions and other structures of injection mould components are designed to be consistent with mould opening direction as much as possible to avoid core reduction, improve the long life of the custom plastic mould.
After injection moulding opening direction is determined, an appropriate parting line can be selected to avoid reverse buckle in the mould opening direction to improve the appearance and performance in plastic moulding manufacturing.
1. Draft angle
* Appropriate drafting angle can avoid product pulling. A smooth surface of the draft should be ≥ 0.5 degrees, fine grain (sand surface) surface is greater than 1 degree, and a rough grain surface is greater than 1.5 degrees.
* Appropriate draft angle can avoid product top injuries, such as top deformation, burst.
* When designing a deep cavity structure, the outer surface slope should be greater than the inner surface slope as much as possible to ensure that the mold core is not biased during injection, obtain a uniform product wall thickness, ensure material strength of opening parts of products.
2. Wall thickness
* All kinds of injection mold components have a certain wall thickness range, generally 0.5~4mm. When wall thickness exceeds 4mm, it will cause the cooling time to be more longer, resulting in shrinkage and other issues. Then we should consider changing the product structure.
* Uneven wall thickness will cause the surface to shrink/pores and weld lines.
* Reasonable application of ribs can increase product rigidity and reduce deformation.
* The thickness of ribs must be less than (0.5 ~ 0.7) T product wall thickness, otherwise the surface will shrink.
* Slope of the rib should be greater than 1.5° to avoid head injury.
4. Rounded corners
* If the fillet is too small, it may cause stress concentration of the product, resulting in cracking of product.
* Too small fillet may cause stress concentration in the mold cavity, resulting in cracking of cavity.
* Set reasonably rounded corners, can also improve processing technology of custom plastic molds such as cavity can be directly processed with R knife milling to avoid low-efficiency electrical processing.
* Different rounded corners may cause movement of the parting line. We should choose different rounding or clearing angle according to the actual situation.
* Shape of the hole should be as simple as possible, generally taking a round shape.
* Same axial direction of hole and mold are the same can avoid core pulling.
* When the aspect ratio of the hole is greater than 2, the draft angle should be set. The diameter of the hole at this time should be calculated according to the size of the small diameter (the largest physical size).
* Length-to-diameter ratio of blind holes generally does not exceed 4 to avoid hole punching in plastic molding manufacturing.
* Distance between hole and edge of the product is generally larger than aperture size.
The core of injection molding ---slider mechanism
When injection mould components cannot be de-moulded smoothly according to mold opening direction, the core puller mechanism should be designed. The slider of the core pulling mechanism can form a complicated product structure, but it is easy to cause defects such as seam stitching and shrinkage of injection mold components and increase the cost of mold to shorten the life of the mold.
When designing injection mold components, try to avoid core structure if there is no special requirement. For example, the direction of the hole axis and rib is changed to the mold opening direction, and the cavity core is used to penetrate.
* Using the toughness of PP material, the hinge can be designed to be integrated with the product.
* Film size as a hinge should be less than 0.5mm and keep even.
* When molding an integral hinge, the gate can only be designed on one side of the hinge.
* Inserting inserts into injection molding product can increase local strength, hardness, dimensional accuracy and set small threaded holes (shafts) to meet various special needs. At the same time, it will increase production costs.
* Insert is generally copper, but also other metal or plastic parts.
* Part of insert embedded in plastic should be designed to prevent rotation and pull out structure such as knurling, holes, bending, flattening, shoulders, and so on.
* Plastic around insert should be properly thickened to prevent stress cracking of injection mould components.
* When designing insert, should fully consider its positioning in the custom plastic molds (hole, pin, magnetic)
Product identification is generally set on the flat surface of the product, and convex form is adopted. Set the mark at the surface where the direction is as close as possible to the mold opening direction to avoid the strain.