Insert Molding
Do you need to improve the reliability and durability or reduce the weight of your parts? Do they need to withstand a variety of environmental or application-related challenges? If so, then insert molding may be a valuable solution for your project.
Insert molding is the process of seamlessly forming a plastic part around a different type of material to enhance its properties. This process creates a tight bond between the insert and the plastic, giving it exceptional strength and durability. This tight integration of metal and plastic can add significant value to your designs while also saving you money.
Often, threaded inserts for injection molding are used to enable assembly with other components. But inserts can also include other components, such as bushings, electrical connectors, magnets and even RFID tags.
How Can Insert Molding Improve Your Parts?
Save Weight & Money // You can use plastic parts with injection molding inserts to replace metal parts with lighter-weight plastic versions that may also be less expensive. Threaded inserts enable you to easily attach plastic parts to other components.
Greater Design Freedom // Metal inserts enable engineers to design parts using thinner walls and simpler geometries than either plastic or metal parts alone may allow.
Assembly Strength // Embedding threaded inserts into your plastic parts enable them to be attached securely to other components, strengthening their mechanical properties. Threaded inserts tend to provide greater assembly strength than inserting screws directly into your plastic parts or gluing them together.
Improved Wear Resistance // Insert molding is often used to create durable handles or grip areas (think of a metal screwdriver with a plastic handle) or to provide reinforcement for high-wear areas, such as knobs or dials.
Improved Alignment // Metal inserts help to keep components properly aligned, simplifying assembly. This is especially valuable for products that need to be serviced repeatedly. Components can be disassembled and reassembled repeatedly without causing degradation of the hole (which can happen when fasteners are screwed directly into the plastic).
Improved Manufacturability // Insert molding can be used to eliminate post-processing steps such as snap fitting or gluing.
Applications of Injection Molding Inserts
Because it’s such a versatile process, insert molding is used in a wide variety of applications, including:
- Auto industry components
- Industrial equipment components
- Medical devices
- Couplings
- Threaded fasteners
- Electrical connectors
- Knobs
Industries Where Inserts are Commonly Used
- Automotive and transportation
- Aerospace
- Medical instruments and devices
- Defense
- Electronics
- Industrial products
- Consumer products
Design Considerations for Insert Molding
A Fathom expert can help you explore the options and estimated costs for your project.
What’s Your Design Objective? When you’re designing a part that will include injection molding inserts, you must consider two factors:
- Torque Loading // How much force can the insert withstand before it breaks loose?
- Pullout Force // How much force is required to break the insert free from the plastic so it can be pulled out?
You need to select inserts that can withstand the loads that the part will be exposed to in its working environment. A Fathom expert can help you select the right insert for your needs.
Part Design for Insert Molding // When designing a part that will include inserts, you need to keep several factors in mind, including:
- The proximity of the inserts to the outside part walls
- Boss design (the inner wall structures that will hold the inserts in place)
- Design for manufacturability (how will the inserts be positioned and held in place until the shot fills the tool cavity)
Failure to plan for these factors can result in cosmetic defects in your parts or damage to the injection molding press. A Fathom expert can help you optimize your part designs and insert selections for the best results.
Heat Pressing vs. Molded-in Inserts // Heat-pressed inserts are inserted into the part after it has been molded. Molded-in inserts are placed into the mold cavity before the shot. The molten resin cools around them and holds them in place. A Fathom expert can help you select the best approach for your application.
Off-the-Shelf vs. Custom Inserts // Depending on your application and where your parts are being injection molded – in the U.S. versus overseas – you may have different sets of insert options. They tend to fall into two categories:
- Off-the-shelf inserts are available in standard designs and sizes. This tends to make them very affordable, especially for larger injection molding projects here in the U.S. But you may be forced to select a “best-fit” option instead of one that is ideal for your application.
- Custom inserts can be machined to the exact length, diameter and configuration you need for your application. This tends to make them more expensive in the U.S. But depending on your needs and part quantities, this option may be surprisingly affordable for overseas injection molding projects.
Why Choose Fathom for Insert Molding?
Fathom has decades of experience in helping our customers with insert injection molding applications in both our U.S. and overseas injection molding operations.
Our U.S.-based engineering team will first learn about your design objectives and then recommend any design, material and insert changes that are needed to help make your insert molding project a success.
