Corner Radius in Plastic Injection Molding, MIM, Die Casting

[A Kiswani]

Greeting to fellow mechanical design engineers,

I have a question, I hope I could find the answer to here.

I have been working on plastic part design for injection molding for a while, and I usually use 0.5 mm+main thickness as a minimum for corner radii on the A-Side of the part to avoid sudden change of wall thickness. It is a safe approach regarding the IM process, but it is not too comfortable in regards to aesthetics.

I am looking at many plastic products in the market, and seems to me that they are designed with very small radii far less than the safe thickness between outer and inner radius.

I tried to apply this in my design, and went against design guidelines found in most reputable literature, but quickly panicked and went back to old design, because I feared sink marks will ruin the final product.

I face similar dilemmas when I work with die cast parts or metal injection molding as well.

Can someone elaborate on this issue? What am I missing? It would be highly appreciated.

Best Regards