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Insert Molding Service
We provide professional insert molding services, integrating metal inserts into precision-molded plastics to produce strong, durable, and assembly-ready components for multiple industries. Our process supports both rapid prototyping and full-scale production with consistent quality and accuracy.al inserts into molded plastics for robust and durable parts suitable for various industries.
- Certified, High-Quality Manufacturing – ISO 9001:2015, ISO 13485, ISO 14001:2015, and IATF 16949:2016 standards ensure precision, reliability, and compliance
- Fast, Cost-Transparent Production – International prototype pricing with tariffs included, delivering quick-turn prototypes and production parts in days
- Prototype-to-Production Scalability – Tight tolerances, repeatable quality, and seamless transition from prototyping to volume manufacturing
Bring your product ideas to life quickly and accurately with our expert prototyping services.
Why Choose Lewei Precision for Insert Molding Services
Lewei Precision delivers reliable insert molding services designed for engineers, product teams, and manufacturers who need strong, accurate, and production-ready plastic components. Our experience, certified processes, and engineering-driven approach ensure consistent quality from prototyping through full-scale production.
Precision Insert Placement
Accurate positioning of metal and custom inserts ensures superior strength, repeatability, and dimensional consistency in every molded part.
Flexible insert molding services support low-volume prototypes, bridge tooling, and high-volume production without changing suppliers.
Experienced engineers provide design-for-manufacturing feedback, material compatibility guidance, and mold optimization to reduce risk and cost.
What Is Insert Molding?
Insert molding is a specialized injection molding process where metal, plastic, or engineered inserts are placed into a mold cavity before molten plastic is injected. During molding, the plastic flows around the insert and solidifies, creating a strong, permanent bond without the need for secondary assembly. Unlike traditional injection molding, which produces fully plastic parts, insert molding services allow multiple materials to be combined into a single, functional component in one manufacturing step.
By permanently encapsulating inserts during molding, insert molding services deliver parts with enhanced mechanical strength, improved wear resistance, and reliable electrical or structural performance. The process reduces part weight compared to all-metal components while increasing durability over assembled parts. These functional and structural advantages make insert molding an ideal solution for applications that demand precision, long-term reliability, and production-ready performance across industries such as automotive, electronics, medical devices, and industrial equipment.
Surface Finish Options for Insert Molding Services
Surface finishes play an important role in both the appearance and performance of insert molded parts. With professional insert molding services, surface finishes can be achieved directly through mold textures or applied after molding to enhance durability, aesthetics, and functionality. The right finish helps improve wear resistance, grip, corrosion protection, and overall product appeal without compromising part integrity.
Achieved directly from polished mold surfaces, ideal for clean, cosmetic parts requiring a uniform appearance.
Mold-applied textures improve grip, reduce glare, and hide minor surface marks on visible components.
A low-gloss surface that provides a refined look while minimizing fingerprints and surface reflections.
Applied post-molding to enhance color, surface protection, and environmental resistance.
Metal inserts can be plated to improve corrosion resistance, conductivity, or visual appeal.
Permanent, high-precision markings for part identification, branding, or traceability without affecting dimensions.
Insert Molding Process at Lewei Precision
Insert Preparation & Placement
Metal or custom inserts are precisely positioned in the mold using fixtures or automation to ensure accurate alignment and repeatable results.
Plastic Injection & Encapsulation
Molten thermoplastic is injected under controlled conditions, flowing evenly around the insert to fully encapsulate it.
Cooling & Bond Formation
The plastic cools and solidifies, forming a strong mechanical and thermal bond that permanently secures the insert.
Part Ejection & Quality Inspection
Finished parts are ejected and inspected for dimensional accuracy, insert integrity, and tolerance compliance.
CNC Machining Solutions
Prototype & Rapid Tooling
Our insert molding services support fast validation and early testing using cost-effective aluminum tooling. This option is ideal for prototypes, design verification, and short production runs, helping you reduce upfront costs while accelerating time to market.
Capability: Low to medium volumes
Lead Time: Fast turnaround for validation builds
Production Tooling
For scaled manufacturing, we provide durable steel molds engineered for long-term, high-volume insert molding services. These tools deliver consistent quality, tight tolerances, and reliable performance across extended production cycles.
Capacity: High-volume production
Lead Time: Optimized for repeatability and efficiency
Materials for Insert Molding
Plastics
ABS is strong, durable, and offers good resistance to heat and impact. It’s preferred for automotive components and consumer goods.
ABS Beige(Natural)
ABS Black
ABS Black Antistatic
ABS Milky White
ABS+PC Black
ABS+PC White
Polycarbonate is extremely durable and has high impact resistance, along with excellent clarity, used for bullet-proof glass and protective gear.
PC Black
PC Transparent
PC White
PC Yellowish White
PC+GF30 Black
PMMA, or acrylic, is known for its crystal clarity and weather resistance, making it ideal for outdoor fixtures and display cases.
PMMA Black
PMMA Transparent
PMMA White
POM is strong, with a low friction surface and good dimensional stability, perfect for precision parts in mechanical applications.
Dark brown (coffee) POM 100AF
POM Black
POM Blue
POM White
Nylon is versatile, strong, and wears well against friction, commonly used for gears, bearings, and other wear-resistant surfaces.
PA(Nylon) Blue
PA6 (Nylon)+GF15 Black
PA6 (Nylon)+GF30 Black
PA66 (Nylon) Beige(Natural)
PA66 (Nylon) Black
Polyethylene is lightweight and has high resistance to impact, widely used in packaging and containers.
PE Black
PE White
PEEK is renowned for its high temperature resistance and strength, often used in aerospace and medical implant manufacturing.
PEEK Beige(Natural)
PEEK Black
Polypropylene is tough, has excellent chemical resistance, and is used for automotive parts, containers, and in packaging.
PP Black
PP White
PP+GF30 Black
Insert Molding vs Overmolding
Choosing between insert molding services and overmolding depends on part function, material requirements, production volume, and performance goals. While both processes combine multiple materials, they serve different manufacturing purposes.
| VS | Insert Molding | Overmolding |
|---|---|---|
| Process Type | Inserts (metal or plastic) are placed into the mold before injection | A second material is molded over an existing plastic substrate |
| Primary Purpose | Structural strength, load-bearing, and functional reinforcement | Improved grip, sealing, comfort, or aesthetics |
| Assembly Requirement | No secondary assembly required | Typically requires a two-step molding process |
| Material Combination | Plastic molded around metal or rigid inserts | Soft materials (TPE, rubber) molded over rigid plastics |
| Mechanical Strength | High strength and durability due to embedded inserts | Moderate strength, focused more on surface functionality |
| Thread & Wear Resistance | Excellent for threaded inserts, bushings, and fasteners | Not suitable for threaded reinforcement |
| Design Complexity | Limited by insert placement and mold design | Greater design freedom for textures and soft-touch features |
| Production Efficiency | Single-shot process reduces labor and cost | Multi-shot process increases tooling and cycle time |
| Typical Applications | Threaded housings, electrical connectors, sensor components | Tool handles, grips, seals, gaskets, consumer products |
| Best Use Case | Functional, structural, and load-bearing parts | Ergonomic, protective, or cosmetic enhancements |
Overmolding Capabilities
Lewei Precision’s wire EDM, part of our CNC services, efficiently crafts both simple and intricate shapes. Ideal for parts requiring high precision, this no-contact method produces minimal burrs and excels with metals like steel and titanium. Favored in aerospace, automotive, and electronics for their accuracy, we ensure tailored, precise solutions regardless of your needs.
Capability
Details/Specifications
Material Compatibility
Stainless Steel, Titanium, Aluminum, Tool Steel, Copper
Tolerance
± 0.0001 inches (0.0025 mm) or better (based on material and thickness)
Maximum Workpiece Size
Length: 16 inches (400 mm)
Width: 12 inches (300 mm)
Height: 8 inches (200 mm)
Cutting Speed
Up to 300 mm2/min (specific to material and thickness)
Surface Finish
As fine as Ra 0.2 µm
Maximum Cutting Thickness
Up to 12 inches (300 mm) – varies based on material
Wire Diameter Range
0.004 inches (0.1 mm) to 0.012 inches (0.3 mm)
Wire Diameter Range
0.004 inches (0.1 mm) to 0.012 inches (0.3 mm)
Wire Diameter Range
0.004 inches (0.1 mm) to 0.012 inches (0.3 mm)
Advantages
Advantages of Precision Machining
Insert molding services offer clear manufacturing and performance advantages by integrating inserts directly into molded plastic parts, eliminating extra assembly steps while improving strength and reliability.
- Eliminates Secondary Assembly Inserts are molded directly into the part, reducing labor, assembly time, and potential failure points.
- Improves Mechanical Strength & Durability Metal or engineered inserts reinforce plastic components, increasing load capacity and structural integrity.
- Reduces Part Size & Weight Insert molding replaces bulky all-metal parts with lightweight plastic-metal hybrids without sacrificing performance.
- Enhances Thread Life & Wear Resistance Embedded metal threads and bushings improve fastening strength and resistance to repeated use.
- Improves Long-Term Reliability Permanent bonding between insert and plastic ensures consistent performance under stress, vibration, and heat.
- Supports Complex Multi-Material Designs Insert molding services enable the integration of multiple materials into a single, functional component.
Applications
Applications of Precision Machining
Insert molding services are widely used across industries that require strong, precise, and assembly-ready components.
- Threaded Housings Plastic housings with integrated metal threads for secure fastening and repeated assembly.
- Electrical Connectors Insert-molded contacts and terminals for reliable conductivity and insulation.
- Sensor Components Precision housings and mounts that protect sensitive electronics and ensure accurate alignment.
- Reinforced Plastic Assemblies Plastic parts strengthened with metal inserts for load-bearing applications.
- Wear-Resistant Mechanical Parts Bushings, sleeves, and contact surfaces designed for durability and reduced friction.
- Structural Plastic-Metal Hybrids Lightweight yet strong components combining the benefits of both plastic and metal.
Quality Control & Inspection for Insert Molding Services
At Lewei Precision, quality control is built into every stage of our insert molding services to ensure consistent performance and reliable results. Before production begins, each mold undergoes thorough pre-production inspection to verify tooling accuracy, insert fitment, and process readiness prior to sampling. During production, in-process inspections are carried out to monitor insert placement, molding consistency, and dimensional stability, helping maintain tight tolerances and prevent defects in real time.
Before shipment, all insert molded parts go through final part validation, including dimensional checks, visual inspection, and functional testing to confirm compliance with design specifications. To support full transparency and traceability, we provide inspection reports, material certificates, and compliance documentation upon request. This structured quality approach ensures our insert molding services meet industry standards and deliver dependable, production-ready components every time.
Overmolding vs Insert Molding
CNC Machining FAQs
1. What is insert molding used for?
Insert molding is used to create strong, functional parts by embedding metal or engineered inserts directly into plastic components. It is commonly applied to threaded housings, electrical connectors, sensor components, and reinforced plastic assemblies.
2. What materials can be used in insert molding services?
Insert molding supports a wide range of thermoplastics such as ABS, nylon, polycarbonate, PP, PPS, and PEEK, along with inserts made from stainless steel, brass, aluminum, copper, and custom-machined metals.
3. Is insert molding suitable for low-volume production?
Yes, insert molding services are suitable for low-volume production, prototyping, and bridge tooling using cost-effective aluminum molds before scaling to high-volume manufacturing.
4. What tolerances can be achieved with insert molding?
Tolerances depend on part geometry and materials, but insert molding can achieve tight, repeatable tolerances suitable for precision assemblies and functional components.
5. How does insert molding help reduce manufacturing costs?
Insert molding eliminates secondary assembly, reduces labor, minimizes fasteners, and improves part reliability, resulting in lower overall production and lifecycle costs.
6. What is the typical lead time for insert molding services?
Lead times vary by tooling and part complexity. Prototypes and samples can be delivered quickly, while production tooling is optimized for consistent, on-time delivery.
7. Do you provide DFM support for insert molding?
Yes, engineering teams provide Design for Manufacturability (DFM) feedback, including insert placement, material selection, and mold optimization to improve quality and reduce risk.
8. Can insert molded parts scale from prototype to production?
Insert molding services are designed to scale smoothly from early prototypes to high-volume production without changing suppliers or processes.
9. How secure is the bond between the insert and plastic?
The insert is permanently bonded during molding through mechanical and thermal encapsulation, ensuring long-term strength, stability, and resistance to loosening.
10. What industries commonly use insert molding services?
Insert molding is widely used in automotive, electronics, medical devices, industrial equipment, and consumer products where durability, precision, and assembly-ready parts are required.
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