Rotational molding, injection molding, and blow molding are three common plastic forming processes. Each has its own strengths and suits different product types. Here is a simple guide to help you decide.
 
1. Rotational Molding – Best for Large size, Hollow, Small-batch custom parts
How it works: Plastic powder is placed in a mold that rotates biaxially while heated. The material melts and coats the inner wall evenly. After cooling, the product is demolded.
Advantages:
· Ideal for large size, hollow, one-piece products (e.g., water tanks, crash barriers, kayaks)
· Uniform wall thickness, smooth corners, supports double-wall structures or metal inserts
· Low mold cost, suitable for small batches and custom designs
Disadvantages: Longer cycle time, not for ultra-high volume production
Typical products: Storage tanks, traffic barriers, playground equipment, large containers, Special-shaped parts
 
2. Injection Molding – Best for Small, Complex, High Volumes
How it works: Molten plastic is injected at high pressure into a closed mold. After cooling, the mold opens and the part is ejected.
Advantages:
· Very high production efficiency, ideal for mass production
· High dimensional accuracy, can form complex geometries
· Good surface finish, little post-processing needed
Disadvantages: High mold cost, not suitable for small batches or large hollow parts
Typical products: Plastic chairs, storage boxes, phone cases, auto interior parts, daily necessities
 
3. Blow Molding – Best for Hollow Containers, High Volumes
How it works: A plastic parison is placed in a mold. Compressed air inflates the parison, pushing it against the mold walls to form the part.
Advantages:
· High efficiency, suitable for large volumes
· Wall thickness can be controlled to some extent
· Cost is between rotomolding and injection molding
Disadvantages: Not suitable for complex shapes or parts with metal inserts
Typical products: Plastic bottles, oil containers, detergent bottles, small hollow containers
 
4. Quick Selection Guide

Your Requirement	Recommended Process
Large hollow part (>0.5m), small batch	Rotational Molding
Small precision part, large quantity	Injection Molding
Ordinary hollow container, large quantity	Blow Molding
One-piece, seamless construction	Rotational Molding
Metal insert or double-wall structure	Rotational Molding

 
Summary
There is no single best process, only the right one for your needs. If you are making large containers, complex shapes, or small-batch custom parts, rotational molding is a strong choice. For large quantity small parts, injection molding is more economical. For standard bottles and containers, blow molding offers high efficiency.
We provide one-stop services for rotational molding equipment, molds, and finished products. If you are unsure which process fits your project, feel free to contact us for a free consultation.