Blow Moulding vs Rotomoulding

Introduction to Blow Moulding

There are a few main blow moulding processes: extrusion, injection and stretch. Extrusion blow moulding is the most common of the three. To start this blow moulding process, plastic pellets must be pre-melted. The pellets are then extruded into a hollow molten tube that is mechanically clamped into the product mould. Compressed air is then added into the tube, which causes the molten pellets to expand and take the shape of the mould. The cooling stage is rapid – once the mould has cooled down (the plastic has solidified and taken its final moulded shape), the mould is opened, and the final product is released ready for the next stage of the process.

Common products made using blow moulding include various plastic bottles and plastic containers, a lot of packaging for cosmetics and toiletries are made using this method including automotive fuel tanks, medical storage containers along with many household cleaning product containers and industrial drums and tanks.

Key Differences Between Blow Moulding and Rotomoulding

A key difference between the blow moulding and rotomoulding methods is the cycle time needed for the manufacturing process. Blow moulding cycles can be quite a lot shorter than most rotomoulding processes, which is why rotomoulding is better suited for more complex mouldings that perhaps require inserts and graphics, along with stringers for spreading loads. Rotomoulding is therefore suited to products that require more attention to detail in their manufacturing process, whereas blow moulding is more suited to less complex product shapes.

The wall thickness of rotomoulded products has the capacity to be thicker than blow moulded products. The moulds used for the blow moulding manufacturing process tend to be more expensive than those used for rotomoulding, but the lifespan of the moulds used for blow moulding tend to be longer.

Different products are more suited to different manufacturing processes. In general, larger, more complex, thicker-walled products are more suited to the rotomoulding process, whereas smaller, simpler products are more suited to the blow moulding process.

Advantages of Rotomoulding

A key advantage of rotomoulding is the design flexibility and complexity, making this manufacturing process more appropriate for more detailed projects. Examples include; indoor and outdoor furniture, sailing dinghies, tanks and bollards. At Rototek, our skilled design team are on hand to fully create your concept, or work alongside your design team.

Another advantage of rotomoulding is that it can create stronger, more durable products, which are capable of having thicker walls than if the product was blow moulded. Rotomoulding is also suitable for mouldings of all sizes, from small 1-litre water containers to large 7-metre sailing dinghies, although less suitable to micro products such as cosmetic packaging. In terms of materials, you can use polyethylene, polypropylene, thermoplastic elastomer, and nylon with blow moulding, as long as the material is in a powdered form.

The main advantage of working with Rototek on your project is our unique approach to optimising designs for rotomoulding. Leveraging our three decades of experience, we use Computer Aided Design (CAD) to create 3D models and then a prototype of your product, allowing us to evaluate the design’s functionality to ensure it performs as intended in real-world conditions.

Advantages of Blow Moulding

The key advantage of blow moulding is the cost-effectiveness for producing large volumes of product, for example thousands of units of cosmetics packaging. On the other hand, rotomoulding is more appropriate for larger, more technical mouldings. Blow moulding is also more suited to the production of smaller, more generic, non-technical products. For example; watering cans, small plastic containers and bottles and household cleaning product containers.

Another advantage of blow moulding is the speed of production. As the cycle time is shorter, you can mould more products in a shorter time frame compared to rotomoulding. However, this often means that the minimum run quantity for a product is much higher.

Although the moulds used within blow moulding are more expensive compared to rotomoulding, the life of these moulds are longer. As with rotomoulding, you can use polyethylene, polypropylene, thermoplastic elastomer and nylon with blow moulding, as long as the material is in pellet form. As with rotomoulding, there is the opportunity to add inserts and graphics to your product post-moulding.