The importance of injection molding in the modern world is immense. The global market size was worth $285.5 billion in 2023 and is expected to grow at a CAGR of 4.9% from 2024 to 2030. Injection molding is used across various industries and for many different purposes. You can use it for automotive parts like bumpers, electrical connectors, medical devices, furniture components, consumer plastics, and much more. Injection molding is essential for the production of high-volume precision plastic parts. Some applications, however, require more specialized processes, and that’s where a method like 2-shot injection molding comes in. Let’s explore what this process is, and the reasons why you might consider using it for your next project.

What is 2-Shot Injection Molding?

First, it’s important to understand what 2-shot molding is. In this advanced manufacturing process, 2 separate plastic resins are used. The first material, like a thermoplastic resin, is injected into a mold, which forms the bottom of the part. Then, a second material, typically a more flexible thermoplastic elastomer or rubber, is injected on top of the first. The finished part will then consist of 2 distinct materials.

2-shot injection molding differs from other methods. In traditional injection molding, only one material is used in the mold, so 2-shot is a more advanced process.

Another method is called insert injection molding, where a preformed part, which is often metal, is placed into a mold first before injecting plastic all around it. That creates a single molded plastic piece that is typically much stronger than by itself. Similarly to 2-shot, insert injection molding can combine multiple materials into a single unit.

Overmolding is another common method used in injection molding. This is completed in a single injection cycle, and involves a second material molding over a preformed part of insert, which could be made from metal, plastic, or even another molded material. Instead of combining materials as in 2-shot injection molding, overmolding simply allows one material to be added over a preformed part.

One last method to investigate is gas-assisted injection molding. Here, gas is used to apply pressure to the mold during the cooling process. This allows for less pressure, less materials used, and minimizes the risk of warping. 2-shot injection molding, in contrast, joins 2 different materials while they are still hot.

The Advantages and Challenges of 2-Shot Injection Molding

Now that you know some key differences between 2 shot molding and some other methods, let’s look at the advantages and disadvantages of this process so you can decide if it’s worth it for your next project.

Advantages

There are several advantages to using 2-shot injection molding. For instance, it allows you greater design versatility because you can choose different materials to join, leading to a greater visual appeal.

It can also lead to enhanced part performance as you can increase functionality by adding features like seals or soft-touch grips without sacrificing the aesthetics. This can also lead to improved part quality and enhance product differentiation. As this method only involves a single machine, you can also save time and money on your project, and its precise injection method can also result in reduced waste and scrap.

Disadvantages

Despite these benefits, there are some challenges associated with 2-shot injection molding. For example, this process involves complex tooling, which might mean a substantial initial investment. Tooling wear and maintenance also requires an additional cost. It’s also important to make sure that the materials you are joining are compatible, so this method may also involve some more extensive planning and design.

When 2-Shot Injection Molding is the Best Option

2-shot molding is used in many different industries. For instance, it is often used in medical applications, because it can create multi-component devices and allows for better color coding and identification.

This type of injection molding is also used in pharmaceutical applications. It allows for certain items to be better sealed against contaminants, which is why it is often useful for drug delivery systems or other packaging components.

Those sealing properties are also a reason why this type of injection molding is used in lab consumables, as well as its capability to produce parts with biocompatible components. It is also used in certain electronics for its encapsulation and sealing properties, such as keyboards and keypads.

The aerospace industry also utilizes 2-shot molding because it allows for more lightweight structures, as well as additional properties that are useful for functionality, like vibration dampening and shock absorption. It’s molding is versatile and allows for many applications across different industries.

Get 2-Shot Injection Molding Solutions from Westec

It’s clear that injection molding offers many benefits. At Westec, our California-based injection molding company can help you capitalize on those advantages. With over 55 years of experience with injection molding, we provide complex and high precision parts for a variety of industries and injection molding services, like design, prototyping, production, and sub-assembly. In addition to our injection molding services, we also provide mold building and secondary operations, like roll printing, hot stamping, vibration welding and much more.

If you’re ready to get started with premier injection molding services, connect with Westec today.