Have Questions or a Custom Project? Give Us A Call (281) 648-0909
Thinking About Rotational Molding?
Here’s What You Need to Know
If you’re looking into making a plastic product and wondering whether rotational molding is the way to go, you’re in the right place. At Sherman Roto Tank LLC, we work with all kinds of businesses to turn their ideas into durable, high-quality plastic parts.
Here’s a simple breakdown of how rotational molding works, what to think about during the design phase, and what info we’ll need from you to give you an accurate quote.
So, What Is Rotational Molding?
Rotational molding, also called roto molding, is a process used to make hollow plastic parts. Think tanks, bins, containers, playground equipment, coolers… that kind of thing.
Here’s how it works:
1.
We pour powdered plastic resin into a mold.
2.
The mold gets heated while rotating in two directions.
3.
The plastic melts and sticks to the inside, creating an even layer.
4.
The mold cools down, and we pop out the finished part.
There are no seams, no pressure, and you get a tough, uniform product every time.
Things to Consider When Designing a Roto-Molded Part
If you’re new to roto molding, some design tweaks can save time and money—and make your product better. Here’s what to keep in mind:
Wall Thickness: Keep it consistent if you can. Thicker walls = longer cycle times and higher cost.
No Undercuts: These make it harder to remove the part from the mold and can add cost.
Draft Angles: Add a slight angle (about 3° or more) to vertical walls to help release the part.
Ribs Are Better Than Thick Walls: If you need strength, add ribs or contours instead of bulking up the wall.
Keep the Mold Simple: Simpler molds = lower tooling cost and faster turnaround.
If you’re not sure about the design, we’re happy to look over your CAD files and give you feedback before you commit to tooling.
What Affects the Price?
Size and Shape: Bigger or more complex parts cost more to mold.
Material: Polyethylene is standard and affordable. If you need UV protection, flame resistance, or food-grade resin, those options are available—just a bit more expensive.
Mold Tooling: Aluminum molds cost more upfront but last longer. Keep the design simple to save here.
Production Volume: Higher volumes lower the per-part cost, even though the process is great for small-to-mid runs.
Extras: Inserts, graphics, trimming, assembly, or special finishes all add to the total cost.
What We Need From You to Give a Quote
To get the ball rolling and give you a solid quote, here’s what we’ll need:
A 3D CAD file of your part (STEP or IGES is best). If you don’t have that yet, a detailed drawing works too.
Your estimated order volume (monthly or yearly).
What material you want—or tell us what it needs to do, and we’ll recommend one.
Any color preferences.
Any critical dimensions or tolerances we need to hit.
Info on inserts, threads, graphics, or post-processing, if you need any.
Optional but helpful: a target price or budget range.
Schedule a Discovery Call
Want to discuss the details of your custom project with our team? Click the button below to schedule a call to review the details of your project and get a better understanding of next-steps.
Download Our Mutual Non-Disclosure Agreement
We understand how critical your intellectual property is to you and your business. Protecting your ideas, strategies, and confidential information is essential.
To ensure peace of mind as we discuss potential collaboration, please download and review our Mutual Non-Disclosure Agreement (NDA) below.