What is custom plastic injection molding and Why Do We Use Them?

08, Sep. 2025

 

What is Custom Injection Molding? - RCO Engineering

Have you ever wondered what is custom injection molding? The injection molding process can be used in a wide range of industries, from pharmaceuticals to automotive. It also allows for the production of a variety of products, including plastic parts and medical devices.

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In this article, we'll walk you through custom injection molding and its applications, and give you an overview of the process.

What is Custom Injection Molding?

Custom injection molding is a manufacturing process for producing parts by injecting material into a custom-designed cavity in a mold. It's also known as plastic injection molding, or plastic injection molding.

The custom plastic injection molding process begins when molten polymer is injected under pressure into the custom-designed cavity of a die. The polymer is then cooled and solidified, allowing the part to be ejected from the die. The process can be used for low-volume production runs, or high-volume production of identical parts.

The Benefits of Custom Injection Molding

Custom injection molding is a vrsatile process ideal for producing complex, intricate components with tight tolerances. It also allows for producing high-volume runs of identical parts, making it a cost-effective solution. Additionally, the process is comparatively fast and efficient compared to other plastic forming methods such as machining or 3D printing.

Custom injection molding also offers designers flexibility - components can be created with various shapes, sizes, and colors to suit any product design. Materials used in custom injection molding can range from polypropylene and ABS to nylon or polycarbonate, depending on the necessary strength and flexibility of the finished product.

Who Should Use Custom Injection Molding?

Custom injection molding is an ideal manufacturing process for businesses that must produce complex parts, whether through high volume or low volume methods. In particular, it is suitable for companies in the automotive, electronics, and medical industries requiring quickly and efficiently custom-made components.

With custom injection molding, complex parts can be molded in a matter of hours or days, depending on the complexity and size of the component. This makes it ideal for quick turnaround times and prototyping before full-scale production begins.

The process also offers customers cost savings when compared to machining or 3D printing - as long as the plastic part's design is suitable for injection molding. In addition, custom injection molded parts are typically more consistent in quality and appearance than their machined counterparts.

Customers who use this process also benefit from shorter lead times and a wider range of materials that can be used to create the finished product. This includes a variety of thermoplastics such as ABS, polypropylene, nylon, and PEEK.

Get Started with Custom Injection Molding Today

RCO Engineering is your one-stop shop for custom injection molding. We provide turnkey solutions, from part design and engineering to tool design and build through a prototype or low-volume part manufacturing.

We have been building molds for over 40 years. We have experience making parts for leading automotive, aerospace, and defense brands. This means that you can trust us to get the job done right.

Why Choose Custom Injection Molding for Your Product

Injection molding is one of the most widely used processes in today’s plastics manufacturing industry. And with good reason: injection molding services are fast, flexible, and cost-effective for many diverse projects. The process also accommodates a high degree of customization and complexity in product design.

Still, it's important to point out that the initial tooling costs can be high – and the more complex the mold, the higher your tooling costs. That means it’s a generally more suitable process for large-scale manufacturing. However, there are some specialized low-volume/prototype molding processes we can employ to make it economical for smaller runs as well. And besides – the benefits of our injection molding services in terms of efficiency, precision, quality, and repeatability outweigh the initial setup costs for many diverse product applications.

The company is the world’s best custom plastic injection molding supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.

Below, we give a rundown on the main benefits that injection molding offers when it comes to manufacturing custom, potentially complex plastic products.

The Main Advantages of Plastic Injection Molding vs. Competing Production Processes:

A High-Speed, High-Capacity Manufacturing Solution

Injection molding is a relatively high-speed production process. For high-volume runs, it’s often the most efficient and cost-effective way to produce large quantities of parts in a short amount of time. To put it into perspective, the typical cycle time for each injection molding cycle is usually measured in seconds.

Rapid Injection Molding (RIM) for Quick Turnaround

For your low-volume projects, the speed of the injection molding process equals shorter lead times and the quickest turnaround possible. It also means the potential to more easily scale up to higher capacity in the future. This is especially beneficial to prototyping projects which will later grow into full-scale production.


Rapid injection molding (RIM) is one of the most effective ways to achieve rapid turnaround after the tooling is built – ideal for on-demand products and just-in-time manufacturing.

Design Flexibility and Material Versatility

Injection molding is exceptionally effective at producing intricate and complex plastic shapes with uniform wall thickness. Achieving your custom product designs in a single cycle reduces the need for secondary operations and all of the complications that come with them. Features such as undercuts, ribs, and bosses can be easily incorporated into the design to simplify your overall production process and potentially reduce your cost per part.


Injection molding is also compatible with a broad range of different plastic materials. That means you have flexibility in terms of material selection based on the desired properties of the final product. Material versatility gives you more options for customizing the look, performance, and functionality of your products, as well as more options to meet your unique price targets. 

Extremely Efficient and Cost-Effective for the Right Products

While the cost of designing and manufacturing custom molds can be significant, the relatively low per-unit cost of injection molding quickly decreases as the production quantity increases. That’s why injection molding is particularly cost-effective for high-volume runs, which can easily offset the upfront tooling costs.


Injection molding is sometimes the most cost-effective manufacturing solution even for low-volume runs and certain prototyping projects. We can use special low-volume molds manufactured from aluminum or softer mold steels which are easier to machine and modify, which lowers your upfront costs. However, these materials do come with a shorter service life, which is why we typically opt for tougher tool steels in higher-volume projects.

A Relatively Sustainable Manufacturing Process for Custom Plastics

The injection molding process generates minimal waste, and the excess material can be recycled in many cases. Sprue, runners, and other scrap materials can be reground and reused, contributing to the overall sustainability of the process.


While plastic manufacturing isn’t typically associated with eco-friendliness, injection molding is one of the most efficient means of making many of the critical plastic products in modern life. That efficiency is especially important in the modern marketplace, which increasingly demands greener products and stricter sustainability initiatives.


As a lean manufacturer with a relatively localized supply chain, Premier Plastics is especially well positioned to help American customers achieve better, more sustainable plastic products.


One of the Midwest’s Leading Injection Molding Companies Since

Located in Omaha, Nebraska, Premier Plastics is backed by more than four decades of providing quality American injection molding services.


Originally founded as an Omaha tool and die shop, today Premier has evolved into one of the leading plastic molding companies for the greater Midwest region and beyond. Our company is an ISO : certified manufacturer committed to delivering your products accurately, on-time, and exactly according to your specifications.

Are you interested in learning more about automotive injection molding? Contact us today to secure an expert consultation!