With over 23 years of expertise in high-precision mold making and plastic injection, Goldwin is proud to deliver advanced manufacturing solutions—including insert molding. This process is widely used across industries to produce durable, lightweight components that combine metal and plastic in a single operation.

Understanding Insert Molding

Insert molding is a specialized injection molding technique that embeds metal or other preformed components into a plastic part. The insert—typically made of metal—is placed into the mold cavity, and molten plastic is injected around it to form a finished component. Once cooled, the insert is permanently bonded within the plastic, enhancing the part’s mechanical properties and performance.

How Insert Molding Works

1. Insert Placement: The metal insert is manually or automatically placed into the mold cavity.
2. Injection Molding: Molten thermoplastic is injected under high pressure to encapsulate the insert.
3. Cooling and Ejection: The plastic solidifies around the insert. The mold opens, and the finished part is ejected.
4. Post-Processing: Steps like deburring, heat treatment, and surface finishing may be applied to ensure part quality and durability.

Key Considerations in Insert Molding

• Mold Design: Critical for holding inserts in position and ensuring proper flow of plastic around them.
• Insert Material: Must withstand the high temperature and pressure of the injection process.
• Gap Control: A narrow gap between the insert and plastic ensures better bonding and reliability.
• Molding Conditions: Resin selection and processing parameters must be tailored to the material and application.

Types of Inserts

Goldwin supports a variety of inserts including threaded inserts, bushings, sleeves, and precision pins from trusted brands like PEM, Spirol, Dodge, and Tappex. These components reinforce mechanical strength, wear resistance, and fastening capabilities of plastic parts.

Manual vs. Automated Insert Loading

• Manual Insertion: Ideal for small production runs and complex components requiring inspection.
• Automated Insertion: Preferred for high-volume production due to its speed, precision, and consistency.

Benefits of Insert Molding

• Reduces assembly steps and labor costs
• Improves strength, shock resistance, and reliability
• Minimizes part size and weight
• Allows for high design flexibility with fewer components
• Enhances corrosion and wear resistance

Insert Molding vs. Overmolding

While both insert molding and overmolding involve layering materials, the difference lies in execution. Insert molding involves embedding a separate component into a plastic part using a single shot. Overmolding, on the other hand, uses multiple shots to bond two plastic materials. Insert molding is faster and more cost-effective for combining metal and plastic, whereas overmolding is preferred for soft-touch surfaces or dual-material designs.

Applications of Insert Molding

• Aerospace: Lightweight, high-strength components for interiors, controls, and fixtures
• Automotive: Durable plastic-metal hybrid parts that improve fuel efficiency and reduce assembly costs
• Medical Devices: Sterile, precision-molded housings and inserts for surgical tools and diagnostic equipment
• Consumer Electronics: Threaded inserts and plug housings without the need for adhesives or fasteners
• Defense: Rugged enclosures and functional parts for field-ready equipment

Why Choose Goldwin for Insert Molding?

As a trusted name in precision tooling and injection molding, Goldwin offers fully customized insert molding services to meet your project’s unique needs. From prototyping to high-volume production, we work with your specifications to deliver high-quality, cost-effective results.

Need support with your next insert molding project? Contact us today to learn how our in-house engineering team can help you bring your ideas to life.