Metal + Plastic, One Production Part
Custom Insert Molding Services
Combine metal components and molded plastic in one production part with insert molding coordinated through BGCNC. We help international B2B customers manage the metal insert, tooling, molding, inspection, and delivery in one supply chain—reducing the effort of coordinating separate suppliers.
Our network supports projects using threaded inserts, terminals, bushings, shafts, and other custom metal components. Share your drawings, material requirements, expected quantities, and project stage to request an engineering review and quote.
- Manufacturing partners
- 50+
- Manufacturing engineers
- 10
- Years' experience each
- 10+
How Insert Molding Works
Insert molding is an injection molding process in which a premanufactured component is positioned in a mold before plastic is injected around or through it. The finished part combines the insert's function—such as a thread, electrical connection, or wear surface—with the shape and features of a molded plastic body.
The insert may be made by CNC machining, turning, stamping, or another suitable process. It can then be placed in the mold manually, with a fixture, or using automated loading, depending on part design and production volume. The right approach depends on insert geometry, mold layout, cycle time, and the required level of repeatability.
Insert molding differs from post-molding assembly. Instead of installing a metal part into a completed plastic component, the insert is captured during molding. This can reduce separate assembly steps, but it also makes insert location, mold design, material behavior, and process control central to part performance.
Metal Inserts and Molded Components, Coordinated Together
A common project risk is treating insert production and plastic molding as unrelated purchases. Differences in dimensions, surface condition, revision control, or delivery timing can cause delays and assembly problems.
BGCNC coordinates the manufacturing route across our network of 50+ proven manufacturing partners. Depending on the design, this can include:
- CNC turning or milling for threaded inserts, bushings, pins, and custom metal features
- Stamping or other processes for terminals and formed components
- Injection molding and tooling
- Secondary operations, finishing, assembly, and packaging
- Inspection and production coordination across suppliers
Why one coordinated route
Our broader supplier network gives us options across manufacturing processes. We select partners based on the project's geometry, material, quantity, quality requirements, lead time, and target cost rather than assigning every part to a single factory.
Insert manufacturing
Turning, milling, stamping and forming matched to the part.
Molding and tooling
Tooling design and injection molding aligned with the insert.
Quality coordination
Inspection and documentation planned across suppliers.
Logistics
Packaging and international delivery support.
Engineering Review: Fit, Retention, and Moldability
Insert position and retention need to be considered together with the plastic part's geometry. Our team of 10 manufacturing engineers, each with more than 10 years of industry experience, reviews the design and manufacturing route before production.
Insert location
Datum references, locating features, and the risk of movement during mold closing or plastic flow.
Retention and bond strength
Knurls, grooves, holes, undercuts, or other features that may help mechanically lock the insert into the plastic.
Plastic flow
Gate location and flow direction relative to the insert and thin sections.
Wall thickness and stress
Local geometry that may contribute to sink, cracking, or distortion.
Thermal behavior
The effect of insert temperature, plastic shrinkage, and cooling on fit and part dimensions.
Mold loading and tolerances
Whether the insert is practical to load manually, with a fixture, or through automation—and which dimensions control function.
These are design and process considerations, not assumptions about a one-size-fits-all solution. Recommendations depend on the part, materials, tooling, and inspection requirements.
Managing Insert Position, Deformation, and Consistency
Insert positioning
The mold and loading method need to locate the component repeatably without damaging it. Features such as locating shoulders or controlled contact surfaces may be considered where the design allows. For parts with multiple inserts, the loading sequence and access for operators or automation also matter.
Shrinkage and cooling
Plastic shrinkage and cooling can influence the final relationship between the insert and molded body. Material selection, wall design, gate layout, and process parameters may all affect the result.
Threads and repeat orders
For threaded features, projects may also need a defined approach to protect threads during molding and verify them after production. The appropriate control plan depends on the application and order profile. We can coordinate checks for dimensions and critical features according to agreed drawings and inspection requirements, and for repeat orders, revision and supplier coordination help maintain consistency across production runs.
From Prototype to Repeat Production
Insert molding can be used at different stages of product development, but the best manufacturing route may change as volumes grow. Early prototypes may use machined plastic, 3D printing, or simpler assembly methods to validate fit and function before investing in production tooling. Once the design and demand are clearer, injection molding with inserts may offer a more suitable route.
Our role is to help customers manage the full manufacturing path, not simply quote the molded component while leaving the insert supply and integration to separate parties.
- 1 Drawing and specification review
- 2 Process and material assessment
- 3 Insert manufacturing and sourcing coordination
- 4 Tooling and molding supplier matching
- 5 Prototype or initial production coordination
- 6 Quality planning, inspection coordination, packaging, and international logistics support
Is Insert Molding Right for Your Project?
Insert molding is worth evaluating when a plastic product needs durable threads, electrical terminals, metal bearing surfaces, or other embedded functional components. It may be particularly relevant for robotics, automation, industrial equipment, electronics, instrumentation, testing equipment, and hardware products.
The process can suit high-mix, low- to medium-volume programs as well as repeat production, provided the tooling and loading approach fit the expected quantities. Typical project quantities across our customer base range from 5 to 5,000 pieces, depending on part complexity and manufacturing route.
When another approach may be preferable
Post-mold press-fit assembly
Can be practical when design changes are frequent or volumes do not justify insert tooling.
Ultrasonic insertion
May suit certain thermoplastic parts and standardized inserts after molding.
Overmolding
May be more appropriate when a second plastic material or soft-touch layer is required.
A different manufacturing process
May be more economical when the part geometry or annual volume favors stamping, die casting, or another route.
Our engineers compare design, material, quantity, tolerance, tooling investment, unit cost, and lead time before recommending a path. If a design is still at the prototype stage, we can also discuss how to avoid locking into production tooling too early.
Quality Systems and Project Requirements
Quality requirements vary by product and market. Our manufacturing network includes partners operating under internationally recognized systems, including ISO 9001, IATF 16949, ISO 13485, and AS9100D. Certification availability and scope depend on the manufacturing partner selected and the actual work performed.
If your project requires material traceability, inspection records, specific certifications, or defined acceptance criteria, include those requirements with your RFQ. We can assess partner fit and confirm what documentation is available for the proposed manufacturing route before production.
Request an Insert Molding Quote
Send your 2D drawings, 3D CAD files, insert specifications, plastic material requirements, expected quantities, and target schedule. If available, include critical dimensions, thread requirements, quality documentation needs, and any existing tooling or production history.
Our team will review the manufacturing route, identify information needed for a reliable quote, and coordinate the relevant suppliers. For a project involving multiple parts or processes, include the BOM so we can assess the supply chain as a whole.
Contact BGCNC
- Email: info@bgcnc.com
- Address: Hongrongyuan · Honghu-Technologiepark, Bezirk Longhua, Shenzhen, China
Better Manufacturing in China. Your Global Partner.