Two Core Technologies in Precision Manufacturing: A Popular Science Guide to Insert Molding and Machining Parts

2025-10-29

Discover Bost’s expertise in precision manufacturing with our popular science guide on two core technologies: insert molding and machined parts. Learn how these advanced processes enhance product quality and efficiency in modern industrial applications. Explore innovation with Bost today.

Amid the wave of manufacturing industry upgrading toward "high precision, high integration, and high efficiency", Insert Molding and Machining Parts are undoubtedly two core technologies supporting the development of the industry. The former enables the seamless integration of components made of different materials, while the latter creates complex components with extreme precision. Complementing each other, these two technologies drive product innovation in fields such as automotive, electronics, medical care, and aerospace. As a crucial carrier for these two technologies, high-quality engineering plastics directly affect process performance. BOST (BOST is a professional engineering plastic manufacturer) , as a professional engineering plastic manufacturer, has always provided reliable material support for the stable application of these two technologies.

I. Insert Molding: An Efficient Process for Multi-Material Integration

(I) Technical Definition and Principle

Insert Molding is a precision manufacturing technology that integrates prefabricated inserts with a plastic matrix through an injection molding process. Different from the traditional mode of "injecting plastic parts first and then manually assembling inserts", it realizes "one-step molding", significantly optimizing the production process.

Its process flow mainly consists of three steps: The first step is insert pretreatment, where metal inserts (such as brass screws and copper terminal blocks) or functional inserts (such as ceramic sensors) undergo surface treatment, such as galvanization and coating with adhesives, to enhance their bonding force with plastics. The second step is insert positioning, in which the pretreated inserts are accurately fixed in the cavity of the injection mold using automated equipment to prevent displacement during injection molding. The third step is injection molding: molten engineering plastics (such as PA66 reinforced plastics produced by BOST) are injected into the mold. Under high pressure, the plastic wraps the inserts and fills the mold cavity. After cooling and solidification, the mold is opened, and the finished product with inserts tightly combined with plastic is obtained.

(II) Core Advantages

Insert Molding boasts remarkable advantages. Firstly, it offers more reliable structure: the molecular-level bonding between plastic and inserts avoids loosening and falling-off issues in traditional assembly. For instance, after adopting this process, the service life of automotive electronic sensor components can be increased by more than 30%. Secondly, it reduces costs: by eliminating the manual assembly process, automated production efficiency is improved by over 50%, and parts inventory is also reduced. Finally, it provides greater design flexibility: it can realize the integration of complex inserts, such as the integration of multiple sets of metal terminals with plastic housings, meeting the miniaturization and integration needs of electronic devices.

(III) Application Scenarios

Currently, Insert Molding has been widely applied in various fields. In the automotive industry, this process is used for the metal framework and plastic outer layer of door handles, as well as connector components in the engine compartment. In the electronics industry, the metal pins and plastic casings of mobile phone chargers, and the hinge components of laptops all rely on Insert Molding. In the medical field, the metal interfaces and plastic pipelines of infusion sets, which require sterility and leak-proof performance, are also typical applications of this technology.

UHMWPE Plastic Bush-4

II. Machining Parts: A Precision Process of Meticulous Craftsmanship

(I) Technical Definition and Common Processes

Machining Parts refers to the technology of processing raw materials such as metals, plastics, and ceramics into precision parts that meet design requirements by means of material removal. It is a key method for manufacturing high-precision components.

There are various common machining processes, each suitable for different application scenarios. Milling uses a rotating milling cutter to cut workpieces, enabling the processing of complex shapes such as planes, grooves, and gears. For example, satellite brackets in the aerospace field require five-axis milling. Turning involves rotating the workpiece while keeping the tool fixed, and is used for processing rotating parts such as shafts and sleeves. The turning precision of automotive gearbox shafts can reach ±0.005mm. Grinding polishes the workpiece surface using a high-speed rotating grinding wheel, with surface roughness controllable below Ra0.02μm, making it suitable for optical instrument lens brackets and precision mold cavities. Drilling and boring are used for processing hole structures in parts; for example, micro-drilling is required for machining small holes with a diameter of less than 0.1mm in mechanical watch movement parts.

(II) Core Characteristics and Limitations

The core characteristics of Machining Parts are high precision and high flexibility. In terms of precision, modern numerical control (CNC) machining equipment can achieve micron-level (μm) tolerances, and some high-end equipment can even reach nanometer-level (nm) precision. In terms of flexibility, no molds need to be made, and parameters can be quickly adjusted according to design drawings, making it suitable for small-batch and customized production. For example, customized medical surgical instruments with a production volume of dozens of units can be efficiently manufactured through machining without bearing high mold costs.

However, machining also has limitations. Firstly, there is material waste: the material removal method leads to a raw material utilization rate of usually 60%-80%, which is even lower for complex parts. Secondly, efficiency is relatively low: compared with mass production via injection molding, the processing time per piece is longer. For example, for complex plastic structural parts, injection molding takes 30 seconds per piece, while machining may take 10 minutes per piece. Therefore, in actual production, the process is selected based on part precision and production volume: Insert Molding is chosen for mass-produced parts with medium precision, and machining is used for small-batch parts with high precision.

(III) Application Scenarios

Machining Parts has a wide range of applications. In the aerospace field, aircraft engine turbine blades (made of titanium alloy) require multi-axis milling and grinding to ensure aerodynamic performance. In the precision instrument field, the gears of mechanical watch movements (made of brass) achieve precise transmission through turning and hobbing. In the automotive industry, the brake discs of high-end models (made of cast iron) are processed by lathes to ensure flatness and avoid brake vibration. In the medical field, titanium alloy prostheses for artificial joints need five-axis milling to match the shape of human bones, followed by grinding to improve surface smoothness and reduce human rejection reactions.

Nylon Insulator-3

III. Process Synergy and Material Support from BOST

Insert Molding and Machining Parts are not mutually exclusive; instead, they often work in synergy. For example, for the housing of an automotive electronic controller, metal terminal blocks are first integrated with the plastic housing through Insert Molding, and then high-precision drilling is performed on the mounting holes via machining to ensure assembly precision with other components. For the plastic handle of medical equipment, the initial shape is obtained through injection molding, followed by milling to process anti-slip patterns and button grooves, and finally grinding to improve the surface feel.

In process synergy, the performance of engineering plastics is crucial. They need to meet both the injection molding requirements of Insert Molding (good fluidity and thermal stability) and the cutting requirements of machining (sufficient rigidity and impact resistance). BOST (BOST is a professional engineering plastic manufacturer) , as a professional engineering plastic manufacturer, has launched suitable products for these two processes.

For Insert Molding, BOST has developed high-adhesion PA66 (Polyamide 66) series engineering plastics. These plastics are added with special compatibilizers to enhance the bonding force with metal inserts. They also have good fluidity, enabling rapid filling of mold cavities. Even small parts with complex inserts can be molded without bubbles or shrinkage marks. BOST's PBT-GF20 (Polybutylene Terephthalate with 20% Glass Fiber) material has excellent temperature resistance, which can meet the long-term use requirements of Insert Molding parts in the automotive engine compartment (under high temperature of 120℃) .

For Machining Parts, BOST has launched easy-to-cut PEEK (Polyether Ether Ketone) and PPS (Polyphenylene Sulfide) series engineering plastics. These materials have moderate rigidity, so they are not prone to edge chipping or cracking during milling and drilling. Moreover, they cause less wear to tools, reducing processing costs. For example, the surface roughness of parts processed with BOST's PEEK-1000 material can reach Ra0.8μm, which can be directly used for precision instrument assembly without subsequent polishing. The PPS-GF40 (Polyphenylene Sulfide with 40% Glass Fiber) material has high temperature resistance (with a long-term service temperature of over 200℃) , making it suitable for processing mechanical parts used in high-temperature environments in the aerospace field.

In addition, BOST also provides customized services. A customer once needed to process plastic parts for semiconductor equipment, which required both Insert Molding for combining with metal electrodes and machining for ensuring flatness (with a tolerance of ±0.002mm) . BOST adjusted the material formula to improve fluidity for adapting to Insert Molding and increased the glass fiber content to enhance rigidity for ensuring machining precision. Finally, the qualification rate of the customer's parts increased from 75% to 98%, significantly reducing costs.

IV. Conclusion

The integrated integration of Insert Molding and the high-precision crafting of Machining Parts together depict the technical blueprint of modern precision manufacturing. As the manufacturing industry pursues "lighter, more precise, and more efficient" products, engineering plastics play an increasingly critical role. As a professional engineering plastic manufacturer, BOST will continue to deepen material research and development, provide better solutions for the development of Insert Molding and Machining Parts processes, and help the global manufacturing industry move toward a future of higher precision.

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FAQ

FAQs

What is the minimum order quantity (MOQ)? Do you support small-batch trial production?

The MOQ for standard products is ≥100kg. We support small-batch trial production (as low as 20kg) and provide mold testing reports and performance data feedback.

Can Bost customize modified plastics with special properties?

Yes! We offer modification services such as reinforcement, flame retardancy, conductivity, wear resistance, and UV resistance, for example:
• Adding carbon fiber to enhance stiffness
• Reducing the coefficient of friction through PTFE modification
• Customizing food-grade or medical-grade certified materials

What are the core advantages of Bost engineering plastics compared to ordinary plastics?

Bost engineering plastics feature ultra-high mechanical strength, high-temperature resistance (-50°C to 300°C), chemical corrosion resistance, and wear resistance. Compared to ordinary plastics, their service life is extended by 3 to 8 times, making them suitable for replacing metals in harsh environments.

What is the delivery lead time? Do you offer global logistics?

Standard products: 5–15 working days; custom modifications: 2–4 weeks. We support global air/sea freight and provide export customs clearance documents (including REACH/UL certifications).

How do I select the appropriate engineering plastic grade for my product?

Selection should be based on parameters such as load conditions (e.g., pressure/friction), temperature range, medium contact (e.g., oil/acid), and regulatory requirements (e.g., FDA/RoHS). Our engineers can provide free material selection consulting and sample testing.