Upgrades and Future Trends of Injection Molding Technology Amid the New Energy Vehicle Wave-News

The global automotive industry is undergoing profound transformations driven by electrification, intelligence, and lightweighting. The stringent requirements of new energy vehicles (NEVs) for driving range, safety performance, and environmental standards have brought new challenges and opportunities to injection molding technology. As a core supporting process for lightweight and integrated automotive manufacturing, injection molding has gradually expanded from traditional component production to the field of core structural parts and functional integrated parts through material innovation, equipment upgrading, and intelligent transformation, becoming a key technology for breaking development bottlenecks in the NEV industry. This article focuses on the upgrading paths of injection molding technology guided by NEV demands, analyzes its innovative applications in lightweighting, intelligence, and sustainability, and explores future development trends.

I. Driven by Lightweighting: Breakthroughs in Materials and Processes for Injection Molding

Lightweighting is a core pathway for NEVs to improve driving range. Data shows that for every 100kg reduction in the weight of a battery electric vehicle (BEV), its driving range can be increased by 6%-10%. Leveraging its inherent advantage of "plastic replacing steel," injection molding has achieved the dual goals of component weight reduction and performance improvement through material innovation and process optimization, emerging as a core solution for NEV lightweighting.

(I) Innovative Application of High-Performance Materials

NEVs have much higher performance requirements for injection molding materials than traditional fuel-powered vehicles. These materials must not only meet lightweight needs but also possess special properties such as high temperature resistance, flame retardancy, and aging resistance. In battery pack systems, PC/ABS alloy replaces metal casings, enabling a 40% weight reduction while achieving UL94 V-0 flame retardant rating through modification, effectively ensuring battery safety. The battery pack lower housing of the Tesla Model 3 adopts PP + talc composite material, which meets the low-temperature impact test requirements at -40℃ through toughening modification and is 35% lighter than traditional metal housings.

In high-end models, the application of high-performance engineering plastics is gradually expanding. The motor insulation components of the Porsche Taycan use PEEK material, which can withstand temperatures up to 250℃ with a long-term performance attenuation rate of less than 5%, significantly improving the reliability of the electric powertrain. The subframe of the NIO ET7 adopts glass fiber-reinforced PA66 material, with rib layout optimized through topology optimization algorithms, achieving a 42% weight reduction while meeting the strength requirement of a 1.5x safety factor. As an important direction for environmentally friendly lightweight materials, bio-based plastics have also gradually realized industrial application. The air conditioning ducts of Mercedes-Benz EQ series models use corn starch-based bio-based PA410, whose carbon footprint is 60% lower than that of petroleum-based PA66, balancing lightweighting and environmental protection needs.

(II) Large-Scale Implementation of Advanced Injection Molding Processes

Microcellular injection molding technology has become one of the core processes for NEV lightweighting. The NEO·H550II microcellular injection molding machine developed by Tederic Machinery is equipped with the CellSure® microcellular process. By injecting high-pressure nitrogen (5-30MPa) into the melt to form a uniform honeycomb structure, it reduces component weight by 15% while maintaining original mechanical properties, shortens the single molding cycle by 15%, and reduces energy consumption by more than 20%. With its closed-loop control system, this machine achieves mold micro-opening precision at the ±0.01mm level, raising product qualification rate to an industry-leading level, and has been widely applied in the production of NEV battery pack components, door trim panels, and other scenarios.

Integrated injection molding technology achieves lightweighting and efficiency improvement by reducing the number of parts. Traditional metal engine brackets consist of 5 parts, but integrated injection molding technology integrates them into a single component, reducing weight by 28% and improving assembly efficiency by 35%. The charging port housing of the BYD Han EV is molded from PC/ABS material through insert injection molding process, integrating metal contacts with the plastic housing. Compared with aluminum alloy, it reduces weight by 50% while improving assembly precision and waterproof performance.

II. Empowered by Intelligence: Efficient and Precise Upgrading of Injection Molding Production

The high requirements of the NEV industry for production efficiency, product consistency, and cost control have driven injection molding to transform towards intelligence and automation. Through the in-depth integration of Industry 4.0 technologies and production processes, full-process precise control is achieved.

(I) AI-Driven Process Parameter Optimization

Traditional injection molding process parameters rely on empirical adjustment, which is difficult to meet the production needs of precision components for NEVs. The application of AI algorithms enables dynamic optimization of process parameters. By collecting multi-dimensional data such as mold temperature, injection pressure, and cooling time, a defect prediction model is established to predict quality issues such as sink marks and deformation in advance and actively adjust process parameters. A certain automaker reduced the injection defect rate of battery pack seals from 3.2% to 0.5% through an AI optimization system, while shortening the production cycle by 8%, significantly improving production efficiency and product reliability.

(II) Integrated Application of Fully Automated Production Lines

The integration of automated equipment and injection molding processes has built an efficient and precise production system. Johnson Controls has built a pillar trim production line at its Wuppertal factory in Germany, adopting a fully automated injection molding integration system. ABB IRB 4400 robots are responsible for ultrasonic trimming, laser robots complete fabric cutting, and linear robots realize part picking, placing, and material conveying, forming a seamless process of "injection molding - cutting - trimming."

In the process of large-scale production and technological upgrading in the automotive manufacturing industry, injection molding has become a key process for manufacturing automotive interior and exterior trim, functional components, and electronic systems, thanks to its core advantages such as high design flexibility, controllable cost, and significant lightweight effect. From traditional fuel-powered vehicles to NEVs, the application ratio of injection-molded parts continues to rise, and its process level directly affects the performance, safety, and aesthetics of automobiles. This article will deeply analyze the core application scenarios of injection molding in the automotive industry, explore material selection logic and process optimization paths, and demonstrate its core value in automotive manufacturing.

I. Core Application Scenarios of Injection Molding in Automotive Components

Injection molding technology has strong adaptability, which can meet the functional requirements of components in different parts of automobiles, covering a wide range of fields from non-structural parts to core structural parts, forming a diversified application system.

(I) Interior Components: Balancing Comfort and Precision

Automotive interiors have strict requirements for appearance texture, touch comfort, and dimensional accuracy. Injection molding has become the preferred process for interior component production due to its precise control capability. As the core component of the interior, the instrument panel needs to meet the requirements of structural support, dimensional stability, and weather resistance simultaneously, and is generally molded from PC/ABS alloy material through the gas-assisted injection molding process. This process injects high-pressure nitrogen (5-30MPa) into the melt to push the melt to fill the remote areas of the mold and form a hollow structure, which can effectively reduce sink marks, reduce component weight by 10%-20%, shorten cooling time, and ensure that the surface precision of the instrument panel is controlled within ±0.5mm.

For door trim panels, center console panels, glove boxes, and other components, materials and processes are selected differently according to functional requirements. Door trim panels are integrally injection-molded from PP + talc composite material, integrating functional modules such as storage slots and speaker mounting positions, reducing subsequent assembly processes and improving production efficiency. Due to the need for good surface gloss and painting performance, center console panels mostly use ABS material, and surface scratches and bubbles are eliminated by optimizing melt temperature and cooling rate. The pillar trim panels developed by Johnson Controls for the Opel Astra adopt the in-mold fabric composite injection molding process, realizing the integrated molding of plastic substrate and fabric surface through a fully automated production line, which not only ensures the high-end texture of the interior but also increases the production qualification rate to over 98%.

(II) Exterior Components: Balancing Durability and Aesthetics

Automotive exterior components need to withstand complex environments such as high and low temperatures, ultraviolet radiation, and rain and snow corrosion, and have high requirements for impact resistance, weather resistance, and shape plasticity. As a core exterior component, bumpers are injection-molded from PP + EPDM composite material. The low-temperature impact performance is improved by adding elastomer modification, ensuring no embrittlement at -40℃ and an Izod impact strength of ≥20kJ/m². To adapt to the shape requirements of different models, large precision molds are used in bumper production. By precisely controlling the clamping force (usually 500-1000kN) and injection pressure, flash and dimensional deviation are avoided, and weather resistance and aesthetics are improved through subsequent painting processes.

Grilles, rearview mirror housings, door sill guards, and other exterior components rely on injection molding to achieve personalized design and large-scale production. Grilles are injection-molded from ABS material and then electroplated to form a bright decorative effect, enhancing the visual texture of the vehicle. Rearview mirror housings are made of PC material, which has a light transmittance of ＞85% through modification and possesses UV aging resistance, making it a direct replacement for traditional glass materials to achieve lightweighting.

(III) Functional Structural Components: Ensuring Performance and Reliability

With the deepening of the "plastic replacing steel" trend, injection molding has penetrated into core functional structural components such as engine peripherals and chassis systems. Engine intake manifolds need to withstand high temperatures above 120℃ and engine oil corrosion, and are injection-molded from glass fiber-reinforced PA66 material, with a tensile strength of up to 120MPa, which is 40% lighter than metal components. Meanwhile, the dimensional stability of the components is ensured by optimizing the design of mold cooling water channels to avoid high-temperature deformation.

Transmission components such as door latches and seat adjustment gears are injection-molded from POM material, which ensures the reliability of long-term operation of the components by virtue of its high rigidity, wear resistance, and self-lubricating properties. NEV-specific components such as battery pack peripheral seals and wire harness fixing brackets adopt the insert injection molding process, in which metal inserts are pre-placed in the mold and firmly combined by plastic melt wrapping, replacing traditional welding or snap connections, and improving assembly precision and structural strength.

II. Material Selection and Process Optimization for Automotive Injection Molding

The performance of injection-molded parts depends on the precise matching of materials and processes. Meanwhile, the balance of performance, cost, and efficiency can be achieved through process innovation and quality control.

(I) Core Logic of Material Selection

The selection of automotive injection molding materials must strictly match the functional requirements of the components, forming a differentiated material application system. PP material is widely used in non-core structural components such as bumpers and door sill guards due to its low cost and good impact resistance. ABS material, with its excellent surface gloss and dimensional stability, is suitable for interior components such as instrument panel skeletons and center consoles. PC/ABS alloy, which balances high and low temperature resistance (-40℃~80℃) and impact resistance, is used in components with higher performance requirements such as pillar trim panels and glove boxes. PA6/PA66 has become the preferred material for engine peripheral components by virtue of its high temperature resistance and oil resistance.

For special requirements, materials need to be modified to improve performance: ABS for electronic components is added with flame retardants to meet UL94 V-0 flame retardant standards; PP for structural components is added with glass fiber to enhance strength; PC/ABS alloy for NEV battery pack housings is flame-retardant modified to balance weight reduction and safety. BASF's Ultramid® Endure PA66 material increases conductivity by 10 times by adding carbon nanotubes while maintaining mechanical strength, effectively solving the electromagnetic shielding bottleneck of traditional plastics.

(II) Key Process Optimization Paths

Every link of the injection molding process directly affects product quality. Significant improvements in production efficiency and product qualification rate can be achieved through parameter optimization and technological innovation. In the raw material preparation stage, hygroscopic materials such as PA and PC need to be dried at 80-120℃ for 2-4 hours to ensure the moisture content is below 0.2%, avoiding defects such as bubbles and silver streaks after molding. In the plasticizing and melting stage, a segmented temperature control mode is adopted. For PP material, the feeding section is set at 150℃, the melting section at 200℃, and the nozzle at 220℃ to ensure stable melt viscosity and improve fluidity.

The application of special injection molding processes is the core direction of process optimization. Two-color/multi-color injection molding injects two different materials into the same mold through a rotating mold or a mobile injection unit, such as the integrated molding of the soft TPU grip and hard ABS skeleton of the steering wheel, reducing subsequent assembly processes and improving production efficiency by 25%. Microcellular injection molding technology forms a uniform honeycomb structure by mixing nitrogen with plastic for injection, reducing component weight by 15%-30%. The door trim panels of the BMW 5 Series are produced using this process, achieving a 28% weight reduction while ensuring strength and shortening the injection cycle by 15%.

In terms of quality control, through the precise control of mold temperature (±1℃) and holding pressure (±2MPa), the hole position tolerance of parts is ensured to be ±0.1mm, avoiding assembly interference. Machine vision is used to detect appearance defects, coordinate measuring machines to detect dimensional accuracy, and temperature resistance tests (-40℃~120℃ cycles) to verify performance stability, increasing the product yield from the traditional 95% to over 99%.

III. Conclusion

As a core process in the automotive manufacturing industry, the depth and breadth of injection molding applications directly determine the manufacturing level and product competitiveness of automobiles. From the comfort and texture of interiors to the structural reliability of chassis, from cost control of traditional fuel-powered vehicles to lightweight needs of NEVs, injection molding continues to empower the upgrading of the automotive industry through material innovation, process optimization, and quality control. In the future, as the automotive industry transforms towards intelligence and low carbonization, injection molding will further break through technical bottlenecks, achieve greater progress in material sustainability and process intelligence, and provide more efficient, environmentally friendly, and precise production solutions for the automotive manufacturing industry.