Here’s a comprehensive Rotomolding Design Guidelines. If you’re designing something that needs a durable, esthetically appealing construction, consider using rotational molding. Products manufactured using the rotational molding process are durable and attractive. The rotational molding process is a flexible, low-cost way to develop custom plastic items.
Table of Contents
What Is Rotational Molding?
Rotational molding is a way of producing plastic items. We also call this process rotomolding. It is a low-pressure process that usesheat and biaxial rotation to produce hollow plastic parts using a hollow mold.
Because rotational molding produces hollow, seamless plastic parts, it is ideal for making food containers, storage tanks, trash bins and similar products. Rotational molding companies use this process to make many other items including toys, boats and home storage items.
Benefits of Using Rotational Molding To Create New Products
Compared to other types of manufacturing, rotational molding has many advantages. Products made from rotational molding are:
- Less likely to crack under stress.
- Resistant to chemical corrosion, rot and mildew.
- More affordable than metal manufacturing.
- More adaptable to different designs.
- Durable and dent-resistant.
What Are the Common Design Rules in Plastic Design With Rotational Molding?
Rotational molding may be new to you. For that reason, it’s a good idea to consider the design guidelines that apply to this manufacturing process.
Since the rotational molding process requires manufacturing feasibility from the design, it’s important to follow these rotomolding design guidelines. Rotational molding companies can help you refine your drawings when you’re ready to start.
Initial Concept
When you’re designing a new plastic product, keep three things in mind. First, what exactly is its use going to be? Second, who is going to use it? Third, where will they use it?
For instance, you want to design a food container. Are you designing it for home use, or is it an item commercial use? Does it need to stand up to highly corrosive environments? All these questions will help you refine your idea.
Asking these questions will help you create an initial sketch of your fully functional item. You should also have an idea of its size. For your final step, decide which type of plastic will work best for you item. When you are producing your final rotomolding design, consult with your rotomolding company for expert advice.
Avoid Sharp Edges
Try to minimize sharp corners or edges in your design. Rotational molding is great at creating complex shapes, but it’s not the ideal process for sharp corners. Most rotational molds have a radius on corners. Therefore, trying to use this process to create an item with sharp edges will potentially produce voids . The plastic won’t flow correctly into the sharp corners of the mold. Because of this, your item will be weak in those corners where the plastic didn’t fill correctly. These areas will become weak and susceptible to stress.
How can you fix this problem? One way is to add a simple radius. Make your outside radius a minimum of 0.0625”. Doing this will greatly improve the strength and quality of your item.
Use Rounded Walls
Rotational molding cannot create larger flat surfaces which are perfectly flat without structural features or a crown. Hollow structures with large flat areas can tend to warp. That is why it is difficult to create rotomolded products that have wide, long and flat surfaces.
When you create a rotomolding design, add elements that break up the flatness of the wall. You can add kiss offs, crowns or other elements to prevent a flat surface. Kiss-off ribbing adds another benefit, namely, it makes the plastic more rigid because it supports the product’s inner surface.
Rotational Molding Is Great for Double Wall Construction
Double wall construction is an important design element if you’re creating bins, boats, shipping tanks and insulated containers. Rotational molding is the manufacturing process of choice for designs with double walls.
Other plastic manufacturing methods require you to make two pieces and weld them together. That’s a problem for two reasons. One, it requires more material and more time. Two, it requires you to weld the two pieces together. With the rotational molding process, however, you get a single, seamless piece. There is no need to attach the parts.
Molded-In Through Holes
Using rotational molding makes it easy to add molded-in through holes. As you know, molded-in holes are stronger than machine-produced holes. They’re also more affordable because you don’t need a second process to add the holes. Instead, you can design a molded-in hole directly into your plastic item. Only rotational molding can give you this option. We always recommend molded-in through holes as part of our rotomolding design guidelines.
Design Thin Walls
Rotational molding is ideal for creating objects with thin walls. This makes it ideal for creating insulated containers. These thin walls are sturdy but flexible. If you need thicker or stronger walls, you can add a crown or a dome to the flat surface to make it stiffer. You can also add kiss-off ribs to reinforce the wall.
Add Inserts and Fittings
Rotational molding allows you to mold-in inserts and fittings. Because we add them during the rotational molding process, they are molded into your plastic object. As a result, they’re less likely to get loose or fail. You can add metal plates, molded threads for caps, internal threaded areas, caster mounting locations, and handles.
If you have a product that doesn’t meet these design guidelines, talk to Roto Dynamics. We can help you design the product you need.
Work With the Right Rotomolding Company
There are a lot of rotational molding companies out there. How do you find the right one to create your product?
At Roto Dynamics, we specialize in creating custom rotomolded products. Our experienced, knowledgeable engineers can help you create a final design and choose your materials. We produce everything at our factory in Orange, California. Call us today for help with any rotational molding project.
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