Five Common Errors Of Injection Part Design

Injection molding is a possible solution for the huge number of good quality parts used in many thermoplastics. To get more information about it, you can see our webpages. If you're designing precision injection molding, there're five common errors I've seen engineers and designers after all these years.

No drafts added

Drafting is required in the mold to release the plastic parts from the mold. Plastic usually shrinks to the center of the part. If no draft is done, the part will stick to the mold and will not eject correctly. If possible, each side is designed to be 1 degree, but any draft ingress helps release the part.

Uneven wall thickness

Variable walls are common in part design and it can cause unexpected part properties when forming. Plastics are difficult to flow and transition between uneven wall thicknesses. Thick wall sections produce differential shrinkage, which can cause part deflection. Try to make the walls of the gate area at least thicker and keep thinner at the end of the filling. Shoot 0.080-120" wall thickness and use rib and plaid features in part design.

Select the wrong material

Material selection is another common error I see. The material should be selected according to the location of the part. Parts that live outside should have UV stabilizers to prevent cracking. The load-bearing part should have a fiberglass-like filler to enhance the part. Parts with bearing surfaces should have additives such as lubricants.

Don't embrace radius

In part design, the angular radius is often overlooked. The angular radius strengthens this area and makes it stronger over the long term. Radius reduces the stress concentration and fractures in the plastic part. It also makes the parts look good and reduces the risk of injury in any treatment.

Contact LC Rapid to get some advice on your question or request a quote for your next injection project!