Curves are trending, even in the plastics industry; and we aren’t talking about the new, thicker Barbie doll. When creating the design for your product, an engineer has to consider many things. More than simply, “What is the products end goal?,” he has to consider the mold, the assembly, the type of plastic, and the structure that will best support the stress the plastic product will undergo.
One small but vital part of a design is providing the corners with a radius. This will result in a stronger finished product. Sharp inside corners often are stress concentrated areas of weakness for a plastic part. Often times, adding a radius into the corner for your product design can add cost and complexity, however, this isn’t an area where you should cut corners (pun intended). Radiusing corners for your product design will provide it with additional strength that will provide long-term benefits, since less of your parts will break. The more residual stress on the molded-in part (this can come from any design flaw including the lack of a radius) the lower the impact strength and durability it will have.
The thought behind this is simple. Any stress incurred to the plastic part is concentrated at the corners. Providing each corner with a more distributed surface area for dispersing the pressure reduces the impact of the load. Additionally, the plastic melt flows easier around these softened edges as opposed to sharp edges. Because of this, the injection pressure can be lower, which also provides for less molded-in stress.
Our experienced engineers do not neglect these design advantages. We want to provide you with the most durable product to fit your needs. When it comes to edges, our general rule of thumb is: radius all edges whenever possible for increased part strength.