Combining injection molding with precision CNC machining delivers the best of both worlds: high-volume production efficiency and tight-tolerance finishing for critical features. This integrated approach is the ideal solution for complex plastic components that require both cost-effective bulk production and the dimensional accuracy that molding alone cannot achieve.

Why Combine Injection Molding with CNC Machining

Each process brings unique strengths to the manufacturing of plastic parts:

◆ Injection Molding – produces complex shapes at high volumes with excellent repeatability and low per-part cost. Ideal for producing large quantities of near-net-shape plastic components.

◆ CNC Machining – achieves tight tolerances, smooth surface finishes, and precise features such as threads, bores, and sealing surfaces. Provides the final dimensional accuracy that molding cannot deliver.

By integrating both processes, manufacturers can produce parts that are both cost-effective and precision-engineered, meeting the demands of industries such as automotive, medical, electronics, and industrial equipment.

Common Plastic Components Produced by Injection Molding and CNC Machining

◆ Housings and Enclosures – electronic device housings, instrument cases, and equipment enclosures. Injection molding provides the complex shape and textured surfaces, while CNC machining adds precision mounting features, connector openings, and threaded inserts.

◆ Mechanical Components – gears, pulleys, rollers, and cam mechanisms. Molding produces the basic geometry, and machining delivers accurate bore diameters, keyways, and tooth profiles.

◆ Sealing and Fluid Components – valve bodies, pump housings, and fluid connectors. Post-machining provides smooth sealing surfaces, precise O-ring grooves, and threaded ports.

◆ Medical Device Components – instrument housings, fluid handling parts, and precision structural components. Machining ensures the tight tolerances and smooth surfaces required for medical applications.

◆ Automotive Interior and Underhood Parts – sensor housings, connector bodies, structural brackets, and fluid manifolds. Post-machining achieves the fit and assembly precision required for reliable automotive systems.

Our Injection Molding Capabilities

◆ Full Range of Press Sizes – We operate injection molding machines from 80 tons to 1,000 tons, enabling us to produce components ranging from small precision parts to large structural housings.

◆ Wide Material Selection – We work with a broad range of engineering thermoplastics, including ABS, PC, PA66 (nylon), PBT, POM (acetal), PMMA (acrylic), PEEK, PEI, and glass-filled grades. Our material expertise ensures that we select the right resin for your mechanical, thermal, and chemical requirements.

◆ In-House Tooling Design and Manufacturing – Our experienced tooling engineers design and manufacture precision injection molds in-house. We utilize advanced mold flow analysis to optimize gate locations, fill patterns, and cooling channels, ensuring consistent part quality and reduced cycle times.

◆ Multi-Cavity and Family Molds – For high-volume programs, we design multi-cavity molds that increase productivity and reduce per-part costs. Family molds allow multiple different parts to be produced in a single shot, streamlining assembly.

◆ Overmolding and Insert Molding – We offer overmolding of soft-touch materials onto rigid substrates and insert molding of metal components such as threaded inserts, pins, and contacts.

Our CNC Machining Capabilities for Molded Parts

Once the plastic component is molded, our CNC machining center performs precision finishing operations to achieve final dimensions and functional features:

◆ CNC Milling – for precision flat surfaces, slots, pockets, and complex contours on molded parts. Ideal for post-molding operations where molded features require refinement.

◆ CNC Turning – for cylindrical components such as rollers, pulley cores, and precision spacers. Achieves excellent roundness and surface finish.

◆ Drilling and Tapping – produces clean, accurately located through-holes, blind holes, and threaded holes for assembly and fastening. Threaded inserts can also be machined into molded holes.

◆ Boring and Reaming – achieves tight diameter tolerances and excellent surface finish on bearing bores, guide holes, and sealing surfaces.

◆ Chamfering and Deburring – removes sharp edges and flash from molding, ensuring safe handling, clean assembly, and proper fit with mating components.

◆ Tolerance Control – we hold critical features to plus or minus 0.02mm or better, ensuring that molded and machined components meet the most demanding assembly requirements.

Critical Features Machined After Injection Molding

◆ Bearing and Bushing Holes – precise diameters with excellent roundness and surface finish for proper bearing fit and long service life

◆ Sealing Surfaces – smooth, flat faces with controlled surface roughness (Ra 0.8 to 1.6 micrometres) for reliable O-ring and gasket sealing

◆ Threaded Holes and Ports – clean, accurate threads for fasteners and fluid connections

◆ Mounting and Locating Features – precise holes and surfaces for assembly and positioning

◆ Insertion and Press-Fit Features – accurately sized holes for metal inserts, pins, and bushings

◆ Edge Finishing – clean, burr-free edges for safe handling and proper fit

Common Engineering Plastics for Combined Molding and Machining

◆ ABS – good impact resistance and machinability. Ideal for housings and structural components.

◆ PC (Polycarbonate) – high strength and transparency. Used for lenses, housings, and precision components.

◆ PA66 (Nylon) – excellent wear resistance and toughness. Suitable for gears, bearings, and structural parts. Glass-filled grades offer increased strength and stiffness.

◆ POM (Acetal/Delrin) – excellent dimensional stability and machinability. Ideal for precision mechanical components, gears, and bushings.

◆ PMMA (Acrylic) – optical clarity and weatherability. Used for windows, displays, and lighting components.

◆ PEEK – high-temperature resistance and exceptional mechanical properties. Used in aerospace, medical, and automotive applications.

◆ PEI (Ultem) – high strength and thermal stability. Suitable for electrical and aerospace components.

Material Considerations for Post-Machining

◆ Glass-Filled Materials – glass-filled grades (such as PA66-GF30) require specialized tooling and machining parameters to minimize tool wear and maintain surface finish. Our experience with these materials ensures consistent quality.

◆ Amorphous vs. Semi-Crystalline – amorphous materials (PC, PMMA) machine with clean, chip-free edges, while semi-crystalline materials (POM, PA66) may require careful cutting parameters to achieve optimal surface finish.

◆ Stress and Warpage – machining can relieve internal stresses in molded parts, potentially causing warpage. We account for this in our machining strategy and recommend appropriate fixturing and cut sequences.

Quality Assurance in Integrated Molding and Machining

◆ Incoming Molding Inspection – all molded parts are inspected for dimensional accuracy, flash, and cosmetic defects before machining

◆ In-Process Monitoring – during machining, we monitor critical dimensions and surface finish to ensure consistency

◆ Final CMM Inspection – finished components are verified on coordinate measuring machines to confirm all dimensions and tolerances

◆ Surface Finish Testing – portable roughness testers verify that sealing and bearing surfaces meet specification

◆ Assembly Fit Testing – parts are tested with mating components to ensure proper fit and function

Why Choose Us for Your Injection Molding and CNC Machining Needs

◆ Integrated Expertise – with both injection molding and precision machining under one roof, we eliminate the coordination challenges of multiple suppliers, reducing lead times and ensuring single-source accountability.

◆ Quality Focus – our IATF 16949 and ISO 9001 certifications demonstrate our commitment to quality in both molding and machining.

◆ Cost Efficiency – by integrating both processes, we optimize the balance between molding and machining, ensuring you receive the highest quality parts at the most competitive price.

◆ Responsive Service – our dedicated project team provides clear communication, technical support, and timely delivery from prototyping to full production.

Contact us today to discuss your injection molding and CNC machining project. Send your drawings and requirements for a free process recommendation, engineering consultation, and competitive quotation.