Insert molded plastic is a type of plastic made from the process of injection molding. The plastic material is injected into a cavity or mold and surrounds some type of an inset that is placed in the same mold before the plastic is melted. This particular molding process was originally created to encapsulate wire-plug connections inside electrical cords. There are now many uses for insert molded plastic materials such as threaded fasteners, bifurcations and other types of electrical components that need to be encapsulated.

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Insert molding, overmolding

Insert molding is the process that creates insert molded plastic products. The process uses a specific mold that opens as it cools to release the finished product. Additional work, such as circuit testing or die cutting, may be needed.

I recommend: Plastics Tech provides an outline of the process of insert molding.

Automatic mold

An automatic mold is a mold that can repeatedly go through the molding cycle without any assistance from an operator.

I recommend: AB Plastic Injectors provides examples of semi-automatic and automatic injection molding machines that use automatic molds.

A-side, stationary side

The A-side, or stationary side, of a mold is the half that mounts to a fixed part on the molding press. The A-side of the mold does not contain the ejector pins to make the visual side of the mold.

I recommend: Protomold provides information on choosing the right A-side and B-side of the mold to get the best finished product.

Ejector pin, ejector sleeve

An ejector pin is a sleeve, blade or pin that pushes the finished material out of a mold. The pins are attached to an ejector plate that is actuated by a press or auxiliary air cylinders.

I recommend: Plastics Technology describes a new system of ejection that does not use pins or sleeves. Ferris State University provides an animation of how an ejector sleeve works.

Plastic types

There are many plastic materials used in insert molding processes. The most important aspect of any plastic used in injection and insert molding is the ability to properly melt and cool with little mold shrinkage.

I recommend: Custom Part provides a chart that describes the specifications of different plastic materials used in injection and insert molding processes.

Antistatic agent

An antistatic agent is an additive in the plastic. This additive is used to improve the plastic for electrical conductivity. This allows any charge used with the plastic to go to ground instead of remaining in the part.

I recommend: Shanghai Jinshan Chemical provides information on antistatic agents used specifically for PE, PET and PVC plastics.

Gather information about insert molded plastic as it pertains to your company's needs. Inserts for plastic are used in many industries and for a number of applications. Insert molded plastic can be created in a standard form or a custom-molded insert, depending on your needs.

Plastic inserts provide durability, customization and versatility over many other molded insert materials. In addition, they also offer the advantage of mixing materials, like plastic and metal, to accommodate the function of the insert. To find reputable molded plastic manufacturers, you should:

1. Find industrial molded plastic suppliers for heavy-duty molded inserts.

2. Buy custom molded insert products to fit your specialty plastic insert needs.

3. Consider insert molded plastic suppliers that offer additional services for in-house tooling and customization.

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Buy industrial insert molded plastic from a reputable manufacturer or supplier

Buying from a reputable manufacturer or supplier is vital to the quality of the product, the integrity of the process and your future relationship with the supplier.

I recommend: You can get threaded plastics inserts and a number of other molded inserts from American Precision Products. The latest plastics technology and 11 plants worldwide make EVCO Plastics a leader in plastic insert molding. Gallagher offers a variety of plastic molded insert applications and products all designed with years of expertise.

Find a custom plastic molded insert manufacturer

Custom plastic molded inserts allow you the freedom to design a plastic molded insert to fit your specific needs, instead of crafting your needs around the available plastic inserts. Many custom molders work with both plastic and metal components.

I recommend: Res-Tech is a leading manufacturer of custom plastic molded inserts and can customize inserts to fit most any molding with plastic-on-plastic and plastic-on-metal. Universal Moulders offers short-run, customizes plastic inserts for small orders and economical tooling with your own design or help from their design department.

Select insert molded plastic manufacturers who offer additional services

Use insert molded plastic companies that offer additional services, like tooling and designing to delegate a majority of the project to the professionals who know how to handle it. Build a solid relationship with the plastic insert company for reliable designs and quality products with future products.

I recommend: Custom Molders offers custom plastic molded insert made in a variety of machines, from 50 ton to 725 ton injection. They also offering tooling and design services for comprehensive assistance for your plastic molded inserts. A&S Mold and Die offer one-stop shopping for all your molded insert needs from a variety of materials and services.

Tips & Tactics

Helpful advice for making the most of this Guide

• •  Ask other companies in your industry who they trust with their insert molded plastic needs and don't be afraid to ask the insert company for references.