Insert injection molding is the process of forming plastic around a non-plastic insert, which can be as simple as a metal rod or as complicated as a battery. When plastic is molded onto the insert, the two components augment each other, resulting in a more reliable final product that offers advantages from both materials. Usually, engineering plastics are used for insert injection molding because of their superior characteristics, such as their resistance to damage, their tensile strength, and their low weight.
At Plastic Design International (PDI), we provide in-depth, comprehensive insert injection molding services and work with various plastic grades, including both consumer and engineering grade plastics. We also operate 21 different molding machines, including robotic sprue pickers, automated conveyors, coordinate-measuring machines (CMMs), and a vertical press that uses a rotary table and engineering-grade plastics. Our advanced setup and over 40 years of experience allow us to handle even the most complicated assignments with reliability and precision.
Vertical Presses with Rotary Tables
Compared to horizontal molding machines, vertical presses are usually more versatile and efficient. At PDI, we pair our vertical press with a rotary table, which allows us to make the mold and insert the part at the same time. A rotary table holds two B halves of a mold so the operator is able to add inserts to one B half while the second B half is molding product and mating with the A half. Vertical presses that use rotary tables are precise and methodical, making them ideal for processing complex inserts.
Engineering Grade Plastics
Commodity plastics can be used in many different applications. However, they are relatively weak, unsuitable for high temperatures, and susceptible to chemicals.
Engineering-grade plastics, on the other hand, have better mechanical and thermal properties than commodity plastics. They are durable, fire-retardant, and chemical-resistant, making them perfect for specialty applications such as those found in the medical and safety industries. Examples of engineering grade plastics available with insert injection molding include:
- Glass-filled nylon
- Polyether ether ketone (PEEK)
- Acrylonitrile butadiene styrene (ABS)
Insert Injection Molding vs. Injection Molding
Insert injection molding and injection molding are similar processes, but inserts add durability and strength. For example, two plastic components that mate together to form a hinge can be made with standard injection molding. If the components are going to be used in a weight-bearing application, however, metal inserts are needed to create more stability. Components made with insert injection molding are stronger than standard plastic parts but still lighter and less prone to corrosion than metal.
Overall, inserts are used in applications where characteristics of both the plastic and the insert material are needed.
What Is the Difference Between Insert Injection Molding and Overmolding?
Overmolding is a compounding process that molds an additional layer of plastic over a previously molded component. Additional inserts are not incorporated into the component for the purpose of augmenting it like they are during insert injection molding, which is also only a one-step process.
At PDI, we offer injection molding, insert injection molding, and overmolding to address our customer needs. At this time, we don’t provide two-shot injection molding.
Having Trouble Deciding Which Injection Molding Process Is Right for Your Application?
Injection molding processes are somewhat similar, but certain methods are best suited to specific applications. Injection molding usually works better for creating simple, lightweight components that are cost-effective; insert injection molding is best reserved for products that demand durability and are more expensive to produce; overmolding is ideal for components with multiple layers.
For help deciding which injection molding process you should use, contact Plastic Design International. If you already have an idea about what you need, request a quote online today and we’ll respond as quickly as possible.