Friday, September 14, 2007

Wall Thickness Design - Maksimum

Dependent on the part design and size, typically, for injection molded parts, the wall thickness will be in the range 0.5 mm to 4 mm (0.02 - 0.16 inch).
For parts made from most thermoplastics, nominal wall thickness should not exceed 4.0 mm. Walls thicker than 4.0 mm it is will increase time required for cooling and will result in increased cycle times

Changing the wall thickness of a component has a significant effect on the following key properties:

1.component weight
2.achievable of cycle time because more time 3.for cooling and injection
4.tolerances of product
5.achievable flow lengths in the mould
6.production cycle time of the component
7.rigidity of the moulded part
8.quality of the component in terms of surface finish, warpage and voids.
9. will affect to determines mechanical properties

What the Disadvantage when Thickness not Uniform

In the design of plastics components, it is important to aim for uniform wall thickness. Different wall thicknesses in the same component cause differential shrinkage which, depending on component rigidity, can lead to serious warpage and dimensional accuracy problems

what we should do when design a mold that have different thickness, look at the following picture, we should make as possible uniform or make the transition of product is gradual

Generally, the maximum wall thickness used should not exceed 4 mm. Thicker walls increase material consumption, more need time for cycle time considerably, and cause high internal stresses, sink marks and voids, look at picture below