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Rotational molding (rotomolding) is a versatile manufacturing process for producing large, hollow plastic products like water tanks, agricultural equipment, and industrial containers. Selecting the right rotomolding materials is critical for product performance, durability, and cost-effectiveness.
At DONGGUAN FOREVER CO.,LTD, we supply engineering plastics to rotomolders across Bangladesh and South Asia. In this comprehensive guide, you'll learn:
What materials work best for rotomolding
Key properties for rotomolding grades
Applications: water tanks, agricultural equipment, industrial containers
How to optimize cost and performance
Common rotomolding defects and solutions
How to get free samples for testing
Loading: Plastic powder loaded into mold
Heating: Mold rotates in oven, material melts and coats interior
Cooling: Mold cooled while rotating, part solidifies
Unloading: Finished part removed from mold
Large, seamless parts possible
Low tooling cost compared to injection molding
Uniform wall thickness
Excellent impact strength
Stress-free parts
| Type | Properties | Applications |
|---|---|---|
| LLDPE (Linear Low-Density PE) | Good impact, flexibility, chemical resistance | Water tanks, storage containers |
| HDPE (High-Density PE) | Higher stiffness, strength | Industrial containers, crates |
| Cross-linked PE (PEX) | Enhanced temperature resistance | Hot water tanks, chemical containers |
| Property | Value |
|---|---|
| Melting Point | 160-170°C |
| Density | 0.90-0.91 g/cm³ |
| Heat Resistance | Up to 120°C continuous |
| Chemical Resistance | Excellent |
| UV Resistance | Good (with stabilizers) |
Advantages of PP for Rotomolding:
✓ Higher temperature resistance than PE
✓ Better stiffness and strength
✓ Excellent chemical resistance
✓ Food-contact approved grades available
✓ Recyclable
Used for fuel tanks, chemical containers requiring superior barrier properties.
Used for specific applications requiring flexibility and weather resistance.
| Property | Ideal Range | Why It Matters |
|---|---|---|
| Particle Size | 35-100 mesh (150-500 microns) | Affects flow and melting |
| Bulk Density | 0.35-0.45 g/cm³ | Affects loading consistency |
| Melt Flow Index | 3-8 g/10min | Affects material flow during molding |
| Property | Importance |
|---|---|
| Thermal Stability | Must withstand extended heating without degradation |
| Melting Range | Narrow range for consistent molding |
| OIT (Oxidative Induction Time) | Longer OIT = better thermal stability |
| Tank Type | Recommended Material | Key Requirements |
|---|---|---|
| Residential Water Tanks | LLDPE or PP, UV-stabilized | Food-contact safe, UV resistance, impact strength |
| Industrial Water Tanks | HDPE or PP | Chemical resistance, large capacity |
| Underground Tanks | HDPE, high stiffness | Soil load resistance, environmental stress crack resistance |
| Product | Recommended Material | Key Requirements |
|---|---|---|
| Fertilizer Tanks | PP, chemical resistant grade | Chemical resistance, UV stability |
| Spray Tanks | LLDPE or PP | Chemical resistance, impact strength |
| Grain Storage Bins | HDPE or PP, food-grade | Food-contact safe, UV resistance |
| Animal Water Troughs | LLDPE, impact-modified | Impact resistance, UV stability |
| Product | Recommended Material | Key Requirements |
|---|---|---|
| Chemical Storage Tanks | PP or cross-linked PE | Chemical resistance, temperature resistance |
| Waste Containers | HDPE | Impact resistance, chemical resistance |
| Material Handling Bins | HDPE or PP | Impact strength, stackability |
| Product | Recommended Material |
|---|---|
| Playground Equipment | LLDPE, UV-stabilized |
| Kayaks/Boats | LLDPE, impact-modified |
| Furniture | PP or HDPE |
Important for Bangladesh: Products used outdoors in Bangladesh face intense UV exposure. Proper UV stabilization is essential to prevent degradation, fading, and brittleness.
| Type | How It Works | Best For |
|---|---|---|
| Carbon Black | Absorbs UV radiation | Black/dark colored products |
| HALS (Hindered Amine Light Stabilizers) | Scavenges free radicals | Colored products, long-term stability |
| UV Absorbers | Absorbs UV before it damages polymer | Clear/translucent products |
| Stabilization Level | Expected Lifespan (Outdoor) |
|---|---|
| Standard UV | 3-5 years |
| Enhanced UV | 5-10 years |
| Premium UV (Carbon Black) | 10-15+ years |
| Cause | Solution |
|---|---|
| Insufficient venting | Improve mold venting |
| Material degradation | Reduce oven temperature or cycle time |
| Moisture in material | Dry material before use |
| Cause | Solution |
|---|---|
| Uneven cooling | Optimize cooling cycle |
| Uneven wall thickness | Adjust rotation speed ratio |
| Material shrinkage | Use low-shrinkage grade |
| Cause | Solution |
|---|---|
| Material degradation | Reduce heat exposure |
| Incorrect material grade | Use impact-modified grade |
| Insufficient melting | Increase oven temperature or time |
| Cause | Solution |
|---|---|
| Overheating | Reduce oven temperature |
| UV degradation | Use UV-stabilized material |
| Contamination | Ensure clean material handling |
| Application | Economy Option | Standard Option | Premium Option |
|---|---|---|---|
| Water Tanks | LLDPE | UV-LLDPE | PP (longer lifespan) |
| Agricultural Tanks | LLDPE | UV-PP | Chemical-resistant PP |
| Industrial Containers | HDPE | HDPE + UV | Cross-linked PE |
Optimize wall thickness: Uniform walls reduce material waste
Use recycled content: For non-critical applications (check regulations)
Optimize cycle time: Faster cycles = lower energy costs
Buy in bulk: Volume discounts from suppliers
Forever Co., Ltd.
Contact：Elaine
Mobile：+86 135 39 444 950
Email：[email protected]
Add：No. 85, private road, qiwutang Industrial Zone, Wanjiang District, Dongguan City, Guangdong Province, China