Corner angles in rotational molding refer to the rounded edges at the corners of molded parts. Designers apply a radius, or curvature, to part corners to reduce stress concentrations. Rounded corners also help to distribute material evenly for a consistent wall thickness. By contrast, sharp corners can lead to potential stress points and structural weaknesses.
Keep reading to learn more and contact Gregstrom about your next rotomolding project.
Round Parts and Irregular Parts in Rotational Molding
Round parts are ideal candidates for rotational molding, but few parts are perfectly spherical. If your part is irregularly shaped, consider whether the corner angles are 90° or greater. If they are, it will be relatively easy to rotomold your part regardless of the plastic material you select. If your corner angles are less than 90°, however, material selection could affect your part design.
Minimum Corner Angles and Rotomolding Materials
The Association of Rotational Molders (ARM) recommends a minimum corner angle of 30° for polyethylene, a material that Gregstrom Corporation frequently rotomolds. There are several types of polyethylene (PE) that we offer. Choices include linear low-density polyethylene (LLDPE), high density polyethylene (HDPE), and static-dissipative (PE) for electrical and electronics applications.
Avoid Corner Angles That Are Too Small
What’s wrong with corner angles that are smaller than recommended? They could result in parts that are not fully filled out. The plastic tends to “bridge over into these restricted areas”, ARM explains. The results are parts with increased porosity, excessive shrinkage, and warpage. If these problems occur during production, designers risk greater rates of part rejects and higher project costs.
Choose an Experienced Rotomolded and Get Design Assistance
Gregstrom Corporation of Woburn, Massachusetts (USA) is an experienced rotational molder that offers design assistance for rotomolding projects. This includes help with material selection and design recommendations for minimal wall separation and corner radiuses. The guidelines for these two design factors are important, and they apply to corner angles.
Are you planning a plastics project? Do you have questions about rotational molding or how to design a rotomolded part for success? Contact Gregstrom Corporation.
