What Are The Key Points To Pay Attention To When Designing Injection Molds?

What are the key points to pay attention to when designing injection molds?

1. 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 too long cooling time, resulting in shrinkage and other problems, so we should consider changing the product structure.

(2) Uneven wall thickness will cause surface shrinkage.

(3) Uneven wall thickness will cause pores and weld marks.

2. Mold opening direction and parting line

At the beginning of the design of each injection product, the mold opening direction and parting line must be determined first to ensure that the core-pulling slider mechanism is minimized and the effect of the parting line on the appearance is eliminated.

(1) After the mold opening direction is determined, the product's ribs, buckles, protrusions and other structures should be designed to be consistent with the mold opening direction as much as possible to avoid core pulling to reduce seam lines and extend the life of the mold.

(2) After the mold opening direction is determined, an appropriate parting line can be selected to avoid undercutting in the mold opening direction to improve appearance and performance.

3. Demoulding angle

(1) Appropriate demoulding angle can avoid product fuzzing (drawing). The demoulding slope of the smooth surface should be ≥0.5 degree, the surface of fine dermatoglyph (sand surface) shall be more than 1 degree, and the surface of coarse dermatoglyph shall be more than 1.5 degree.

(2) Appropriate demoulding slope can avoid product top damage, such as top white, top deformation, and top break.

(3) When designing deep cavity structure products, the outer surface slope should be greater than the inner surface slope as much as possible to ensure that the mold core is not deviated during injection molding, to obtain a uniform product wall thickness, and to ensure the material strength of the product opening.

4. Reinforcing ribs

(1) Reasonable application of stiffeners can increase product rigidity and reduce deformation.

(2) The thickness of the stiffener must be ≤ (0.5～0.7) T product wall thickness, otherwise it will cause surface shrinkage.

(3) The single-sided slope of the reinforcing rib (Shanghai Mould Design Training School) should be greater than 1.5° to avoid top damage.