Get the Best Parts for Your Application by Understanding Rotational Molding Tolerances
Rotational molding is a common way to produce high-quality, hollow plastic products. However, one of the most challenging aspects of this process is achieving precise rotational molding tolerances. These tolerances are influenced by a unique set of variables, and understanding how they work can help you make informed decisions for your business. In this blog, we’re outlining everything you need to know. Let’s dive in.
What are Rotational Molding Tolerances?
When it comes to manufacturing, tolerances are a crucial part in ensuring the efficacy of a product. A “tolerance” is the amount a dimension can vary from its nominal design while still allowing the part to function properly. Tight tolerances ensure that parts can fit together correctly, perform as intended, and meet safety standards. Even small variations can lead to significant issues in assembly and functionality. Standard tolerances usually fall around +/- 20% for wall thickness and +/-1% for linear dimensions.
Factors Influencing Tolerances
There are a multitude of factors that can affect your rotational molding tolerances. Understanding these considerations can help you make informed decisions for your business.
Material Considerations
The type of plastic used (polyethylene, nylon, XLPE, etc.) can affect shrinkage rates, flow properties, and overall dimension stability. That’s why it’s so important to choose the right material for your specific application.
Mold Design and Construction
The design of the mold, including its geometry and how it’s constructed, plays a crucial role in achieving precise tolerances. Factors such as mold shrinkage and the quality of mold finishes can influence the final dimensions.
Processing Conditions
Temperature and pressure during the molding process are critical. Variations in heating and cooling rates can lead to uneven expansion and contraction, affecting the final tolerances. A quality rotational molding partner will cool the jigs before extraction to hold critical dimensions. They’ll also use secondary fabrication jigs that act as go/no gauges, a FARO arm to check parts, and an ultrasonic thickness probe for nondestructive measurement of wall thickness.
Part Geometry
Complex shapes or designs with varying wall thicknesses can lead to differential cooling rates, resulting in dimensional variations.
Manufacturing Environment
External factors such as humidity and temperature in the manufacturing facility can influence the consistency of the molding process and the material properties.
Post Processing
Additional processes like trimming, machining, or secondary operations can affect the final tolerances of the molded part.
Have Questions About Rotational Molding Tolerances?
If you have questions about rotational molding tolerances, we can help. For over 30 years, we’ve been creating the best rotomolded parts for our customers, ensuring they meet high expectations. Over the years, we’ve helped countless businesses get the right fit for their organization. We’d be honored to help you, too.
At GVL Poly, we can help you from start to finish. Our in-house team can cover everything from design and rapid prototyping to fabrication and logistics. All of our services are backed by experienced machine operators, engineers, designers, tool builders, and other professionals. When you work with us, you can be sure you’re getting the best products possible.
Let’s Get Started
Are you ready to start your next rotomolding project? We’d love to help and answer any questions you may have. Get in touch with us here.
