Rotational Molding vs Injection Molding: Which is The Best?

Rotational molding vs injection molding. Both are popular manufacturing processes for plastic items. Nevertheless, each method has its advantages and disadvantages.

Rotational molding is a great way to design big, intricate plastic pieces with even surfaces, uniform wall thicknesses, and design flexibility. It’s cost-effective, particularly when making low to moderate amounts of items. It also works well with poly-based resins with minor melt viscosity, like polyethylene. In addition, this method makes it effortless to create prototypes and individual components.

In contrast, injection molding enables the mass production of compatible parts at a low cost. As a result, it’s regularly used more for plastic parts with complex specifics and close-fitting tolerances and is ideal for resin materials with higher melt viscosities, like polycarbonate. Additionally, injection molding is an option for large-scale output because it allows for the fast manufacturing of parts with short interruptions.

When deciding whether to go with rotational or injection for a specific project, these three things should be considered:

1. Final product
2. Type of raw material being used
3. Quantity of production

Both processes have their perks and drawbacks, which will depend on the individual goals and objectives of the project. Although both have advantages, there are certain cases where the rotomolded process may come out superior to injection.

The following article below will compare the two manufacturing methods to contrast their strengths and flaws in deciding which one is ideal for your project.

Advantages of Rotational Molding Process

Compared to the injection process, the rotational method can produce larger and more intricate parts with uniform thicknesses and consistent surfaces. While rotomolding just takes longer in the process, it is extremely ideal for intricate details and generating components , such as fuel tanks, kayaks, playground equipment and hollow parts.

The capability to use various materials is also another benefit of rotational manufacturing. This process can utilize materials with low melt viscosities, like polyethylene, and those with higher melt viscosities, such as nylon and PVC. For this reason, rotomolded plastic has become the ideal option for applications ranging from automotive components to marine supplies and recreational vehicles.

In terms of cost, rotational moulding is less expensive than injection for low to moderate volumes of parts. This is because the manufacturing process is generally less complex and requires fewer steps than injection molding, resulting in lower costs for tooling and setup.

Its an ideal selection for those who need to make limited amounts since the method allows for speedy and uncomplicated alterations in design and substance. This versatility makes rotational molding an excellent option for prototypes and one-off components.While injection has its advantages, such as the ability to produce high volumes of identical parts at a low cost.

Rotational molding may be the better choice for  

• Shapes and features for specific applications that require large, complex parts with smooth surfaces
• Consistent wall thicknesses
• The ability to use a wide range of materials
• Low to moderate volumes of parts at a lower cost

Advantages of Injection Molding Process

Injection molding boasts greater capacity when producing multiple copies of identical objects than rotomolding. It is particularly effective as it can efficiently and quickly generate many components – an excellent solution for mass production.

Injection molding is ideal for forming small, accurate components with intricate details and limited allowances. It makes it the right selection for companies that need top precision levels, which include medical instruments, consumer electronics, car parts and injection molded coolers.

Advantages that makes the inject process valuable is its versatility when it comes to material. This process can use high-viscosity melts like polycarbonate and PVC and lower-viscosity melts like polystyrene and ABS. It makes injection molding an ideal choice for a wide array of applications.

When factoring in the price, injection molding is usually pricier than the rotomolding process when producing small-to-moderate parts. But, once the quantity goes up, the cost per part reduces drastically, thus rendering injection molding more affordable for large volumes of identical objects.

Injection molding uses are ideal for large runs as its high output rate allows for many pieces to be made with almost no interruption. This productivity makes injection molding a great choice for mass manufacturing of injection molded products like an elite cooler. Despite the multiple benefits of rotational molding, such as:

• Making complicated parts with even walls and smooth surfaces,
• Utilizing a variety of materials,
• Producing low to moderate amounts of items at reduced costs.

Injection molding is the favored option for specific applications that necessitate high volumes of identical elements at low prices, small components with intricate details and tight tolerances, or execution of high-volume production line.

Why Rotomolding Over Choosing Injection Molding?

There are several reasons why rotational molding may be the better choice over the injection process for a plastic project. Some of the main advantages it offers include the following:

Ability to produce large, complex designs with smooth surfaces and consistent wall thicknesses: 

It’s well-suited for producing parts with intricate details, such as fuel tanks, kayaks, and playground equipment.

Ability to utilize a wide range of materials: 

Rotomolding supports materials with low melt viscosities, such as polyethylene, and materials with higher melt viscosities, such as PVC, nylon and plastisols. This versatility makes rotational a good choice for various applications, including automotive parts, recreational vehicles, and marine products.

Low to moderate volumes of parts at a lower cost: 

Rotomolding vs injection, tends to be less expensive for low to moderate volumes of parts. This is because this process is generally less complex and requires fewer steps than injection molding, resulting in lower costs for tooling and setup.

Flexibility for prototypes and custom parts: 

Roto molding is a good choice for those low-volume production runs, as it allows for quick and easy changes to the design and material of the product. In addition, this flexibility makes it a good choice for prototypes and custom parts.

Please get in touch with R&R Technologies LLC for more information on rotational molding uses and its benefits ! Free estimates are provided! Call 812-526-2655 

FAQ Section: Plastic Rotational Molding vs Plastic Injection Molding

Q: What is rotational molding?

A: Rotational molding, also known as rotomolding, is a production process in which a powder or liquid polymer is placed into a mold, which is then rotated in multiple directions while being heated. The material is evenly distributed throughout the mold as it rotates, forming a hollow, one-piece product when it is cooled, the part is removed.

Q: What are the advantages of rotational molding?

A: It offers several key benefits, such as being able to construct complex mold designs and large pieces with consistent formed wall thicknesses and surfaces, an assortment of materials that can be used in generating rotomolded parts at a cost-effective price.  Individual metal components can be introduced into the mold, forming a part of the final structure. Also because lower levels of pressure are used in rotomolding, less costly molds can be created. Injection molding requires high pressure, and therefore incorporates the use of more expensive and stronger molds.

Q: What is injection molding?

A: Injection molding process begins with the forcing of plastic pellets into a shape in a mold through high pressure. Afterward, the mold is cooled, and the casted part can be released.

Q: What are the advantages of injection molding?

A: One of the biggest advantages of the injection process is its capacity to produce massive amounts of identical parts at an economical price. Injection molding also enables manufacturers to make small, exact injection molded parts with in-depth details and tight tolerances. Additionally, a vast array of materials can be used when utilizing this technique.

Q: Is it possible to produce any plastic product with either rotational or injection molding?

A: Both molding processes can make a large selection of plastic products, but each has advantages and disadvantages. To find the right procedure for a particular task, consider the finished product, the components being utilized, and the amount that needs to be manufactured.