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Insert Molding

Custom Plastic Insert Molding

Insert molding combines plastics and metals into a single assembly. The process of insert molding reduces assembly and labor costs while increasing design flexibility and part performance.  Our vertical injection machines with rotary tables allow us to over mold and encapsulate inserts for electrical circuitry, fastening, and connecting. Common insert molded products include sensors, switches, connectors, and actuators.

Custom Plastic Insert Molding - Insert Molded Automotive Parts


Our insert molding presses range from 55 to 300 tons and are supported by on-press vision inspection systems, which check inserts for proper placement. If any part is not properly positioned, the system prevents the press from proceeding. This ensures the inserts are properly placed and protects the mold from damage.

Fabrik Molded Plastics’ insert molding capabilities include manual and fully automated operations, with additional secondary forming, blanking, and 100% hipot and continuity testing.

Insert Molding Process

Insert molding is a fabrication process that involves molding thermoplastic materials around non-plastic inserts. The non-plastic over molded components includes terminals, stampings, metal rods, and a variety of metal fasteners. This integrated process requires precision molding and strict quality control measures to meet tight tolerance requirements.

Insert Injection Molding vs. Overmolding


Insert molding and overmolding both join solid plastic or metal materials with plastic resin to create an end product consisting of multiple materials.

The two have some key differences. Insert molding involves placing a pre-manufactured metal insert into the mold. Enclosing the insert with plastic creates a single molded plastic component with a bond stronger than can be created using secondary assembly. The insert molding process and be completed through manual loading, but automated loading is more efficient due to its consistency and elimination of human errors.

Overmolding, also called double-shot or two-shot molding, is an injection molding process that involves molding plastic over another plastic molded part during a single manufacturing process. Overmolding combines multiple plastics for either aesthetic or practical purposes, using chemical, mechanical, or both types of bonding. This process is commonly used to manufacture handles for tools like power drills, screwdrivers, and toothbrushes.

Benefits of Insert Molding

Recently, insert molding has changed certain industrial practices. Many industries are replacing metal parts with plastic ones because plastic is less expensive, resistant to corrosion, durable, and lightweight compared to most metals. Here are the benefits of insert molding:

  • Durability: Insert molding offers high precision and enhanced product designs compared to other molding processes. Plastic parts with integrated components are more reliable and robust.
  • Efficiency: Insert molding does not require separate assembly, reducing the risk of manufacturing errors. Because the insert is integrated into the molding step, it saves time and labor costs, increasing the efficiency of your entire operation.
  • Cost-Efficiency: Insert molding is a cost-saving process since it allows the use of less expensive thermoplastic resins, which are more affordable than metals. It also minimizes labor costs and requirements for specialized assembly equipment.
  • Lightweight: Plastic parts are generally 50% lighter than metal but are comparable in terms of strength. This has made many industries opt for plastics to replace metals. The lighter weight contributes to better fuel efficiency in automotive components and easier handling for surgical equipment.
  • Size: Insert molding allows the production of smaller and thinner parts without sacrificing performance and durability.
  • Material Variety: Insert molding uses a variety of common engineering thermoplastics including Nylon, PBT, PEI, PC etc. Many of these plastics are recyclable throughout their life cycle. They are also durable, versatile, and ideal for various consumer and industrial products.
  • Design Variety: The process also allows different types of designs and shapes, expanding possibilities for engineering and design across many fields.

Examples of Insert Molding Applications

Insert molding is applicable in a range of industries for a variety of applications. These are a few common insert molding examples:

  • Consumer Goods: Insert molding is used to create consumer products like storage bins, toothbrushes, plastic containers, and cell phone cases.
  • Automotive: In the automotive industry, gears, knobs, electrical sensors, handles, fasteners, and other automotive parts made of plastic and metal are made through insert molding.
  • Medical: Plastics are easy to sterilize, so medical professionals prefer insert-molded parts for defibrillators, pacemakers, medical cables, and wiring.
  • Dental: Dental professionals rely on insert-molded instruments for easy handling.
  • Defense: Insert molded military products include binocular housings, decoys, battery packs, handheld communication devices, guidance systems, and more.
  • Safety: Because insert molded components are easier to grip, they provide a higher level of safety for users and their operations.
  • Industrial: Various industrial processes require insert-molded parts, including screws, surface mount pads, clips, spring contacts, pins, and more.
  • Electrical/Electronics: Insert molding is used to encase electrical wires in rubber, which makes them waterproof and safer to handle. Insert-molded electronic products include cell phone and computer chargers.
  • Beauty: In this industry, designers use insert molding to create custom packaging — for makeup brushes, perfume bottles, and compacts—that is more eye-catching and attractive to consumers.

Insert Molding Services From Fabrik Molded Plastics, Inc.

Insert molding is a key fabrication process across many industries and offers a wealth of benefits. Fabrik Molded Plastics is a full-service, custom injection molding provider that works with a variety of high-performance engineered thermoplastics. We operate the latest automation and molding equipment, which allows us to compete on an international scale.

Contact us today to learn more about our insert molding services, or request a quote to get started on your solution.

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Custom Insert Molding Specifications

Insert Molded Products


Encapsulated Electrical Components


Vertical Clamp Injection
Rotary Table Presses from 55 – 300 Tons

Secondary Process & Testing

Vision Inspection and Gaging

In-Line Electrical

  • 100% Hipot
  • Continuity

2D & 3D Part and Tool Design


Design for Manufacturability
Resin Selection Assistance
Moldflow Analysis

Program Management & APQP
AIAG PPAP & First Article Inspection


ISO/TS 16949
ISO 9001

FDA & UL Registered