Rotational Molding — Connect with Top Providers
Rotational molding heats plastic powder inside a rotating mold to produce large, hollow, seamless parts like tanks, playground equipment, and kayaks.
About Rotational Molding
Rotational molding (rotomolding) is a process where powdered plastic is placed into a hollow mold that is heated and slowly rotated along two perpendicular axes. The plastic melts and coats the inside of the mold uniformly. After cooling, the seamless hollow part is removed. Rotomolding excels at producing large hollow parts with uniform wall thickness and no seams or weld lines. It is ideal for low-to-medium volume production because tooling costs are significantly lower than injection molding or blow molding. Common products include water tanks, septic tanks, playground equipment, kayaks, coolers, and furniture.
Tolerances
±0.020" (±0.5mm) typical; less precise than injection molding
Lead Time
4-8 weeks for tooling; 2-6 weeks for production
Cost Range
$2,000-$30,000 for tooling; $20-$500+ per part
Compatible Materials
Advantages
- Low tooling costs
- Large parts with uniform wall thickness
- No seams or weld lines
- Design flexibility for complex hollow shapes
- Multiple parts per cycle
- Low stress in finished parts
Limitations
- Longer cycle times (20-60+ minutes)
- Limited material selection
- Lower precision than injection molding
- Surface finish not as refined
- Not suited for very high volumes
Industries Served
Automotive
The automotive industry manufactures vehicles and components, demanding high-volume production, consistent quality, and competitive pricing across a complex global supply chain.
Construction
Construction manufacturing produces structural steel, rebar, building components, HVAC systems, and architectural elements for commercial and residential buildings.
Agriculture
Agricultural manufacturing produces tractors, harvesters, irrigation systems, and precision farming equipment that must withstand harsh outdoor conditions and heavy use.
Marine
Marine manufacturing produces vessels, propulsion systems, and offshore structures that must withstand saltwater corrosion, high loads, and demanding marine environments.
Consumer Products
Consumer products manufacturing produces household goods, appliances, sporting equipment, and personal items through high-volume processes prioritizing aesthetics and cost efficiency.
Rotational Molding FAQ
What size parts can rotational molding produce?
Rotational molding can produce parts from small housings (a few inches) to very large tanks and containers up to 20+ feet in length and thousands of gallons in capacity. It's one of the best processes for very large hollow parts.
Why choose rotomolding over blow molding?
Rotomolding has lower tooling costs (aluminum vs. steel molds), produces more uniform wall thickness, handles larger parts, and is more economical at lower volumes. Blow molding is faster and better for very high volumes of smaller parts like bottles.
What is the minimum order for rotational molding?
Rotomolding is economical even at quantities as low as 25-100 parts because of its low tooling cost. Some shops will produce single prototype parts. This makes it ideal for niche products and low-volume production.
How strong are rotomolded parts?
Rotomolded parts are seamless and have uniform wall thickness, resulting in excellent impact resistance and stress distribution. They are highly durable and resist cracking, making them ideal for tanks, containers, and outdoor equipment.
Can rotomolding produce colored parts?
Yes, color is added directly to the powdered plastic material before molding. Rotomolded parts can be produced in virtually any color. Multi-color and multi-layer parts are also possible with specialized techniques.
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