Plastic body parts moulding

In addition, our company has established cooperative relationships with plastic raw material suppliers, printing manufacturers, etc. to ensure the supply of raw materials and printing quality. Through our rich experience and perfect supply chain, our company can provide customers with high-quality customized plastic body parts moulding products to meet their specific needs. At the same time, we have 10 years of professional foreign trade service experience, understand the foreign trade process, and better serve our customers. For plastic body parts moulding products, we can make corresponding plastic parts, which is mainly done through injection molds.

Plastic body components for electric scooters, e-bikes, and motorcycles—such as full-vehicle shells, front and rear fenders, side panels, footboard covers, battery compartment housings, and handlebar instrument cowls—are large, integrated structural parts. They must simultaneously meet requirements for thin-walled aesthetics, structural load-bearing capacity, and outdoor weather resistance, making the molding process significantly more complex than that of smaller plastic accessories. The complete molding workflow comprises five core stages: raw material pretreatment, large-mold setup and testing, cyclic injection molding, post-molding shaping, and comprehensive quality control. Standardized management throughout the process focuses on eliminating weld lines, minimizing warpage, ensuring aging resistance and dimensional stability, and maintaining impact resistance.

I. Raw Material Warehousing and Pretreatment

Body components are subjected to prolonged exposure to sunlight, rain, and temperature fluctuations. The primary materials used include weather-resistant ASA, ABS+PC alloys, and talc-modified PP. Ensuring material eco-friendliness, proper drying, and accurate mixing ratios is the critical first step in the molding process.

Upon arrival at the factory, materials must undergo verification of material composition reports, UV aging resistance reports, and RoHS environmental compliance certificates. Exterior body shells must be manufactured using 100% virgin material; only regrind from trimmed edges and sprues may be reused in small quantities, with the addition ratio strictly capped at 10%. Structural, load-bearing components—such as battery compartments—strictly prohibit the inclusion of recycled material, as it significantly reduces low-impact strength and increases the risk of cracking during vehicle impacts. For coloring, weather-resistant high-gloss masterbatches are selected and combined with UV-resistant masterbatches and low-migration, eco-friendly mold release agents. The mixture is processed in a low-speed vertical mixer for 8–12 minutes; low-speed mixing prevents frictional heat buildup, thereby avoiding particle agglomeration and uneven pigment dispersion.

Drying and dehumidification directly determine the aesthetic quality of the body components; undried material can cause "silver streaks" and air bubbles, leading to large-scale paint failure after coating. ASA and ABS+PC shells are dried in hot-air dryers at a constant 85°C for 4 hours (extended to 6 hours for ABS+PC alloys) to ensure moisture content remains below 0.04%. Modified PP has extremely low water absorption; drying at 60°C for one hour—necessary only in rainy or humid workshop conditions—is sufficient to remove surface moisture. The large-scale production line is equipped with a centralized, sealed material feeding and dehumidification system; once dried, raw materials are conveyed through sealed pipelines directly to the injection molding machine's hopper, preventing re-absorption of atmospheric moisture.

II. Assembly and Pre-heating/Commissioning of Large Car Body Molds

Given the large projected area of the car body plastic parts, single-cavity large molds are typically employed, featuring targeted reinforcement in mold steel selection, cooling, venting, and ejection systems. The aesthetic cavity utilizes S136 mirror-finish stainless steel, polished to a defect-free surface (no pitting or scratches) to meet high-gloss painting requirements for the vehicle; the cavity for the glass-fiber-filled battery compartment undergoes nitriding treatment to withstand long-term erosion and wear from the hard melt, thereby extending the mold's service life. Wall thickness distribution is uneven; local thickness at reinforcing ribs and mounting bosses reaches 4–6 mm, while the thin-walled shell measures only 1.8–2.2 mm—a disparity that makes the part highly susceptible to sink marks and warpage. The mold incorporates conformal cooling channels, with spiral cooling cores installed inside thick-walled bosses to balance the overall cooling rate. Continuous, fine venting slots (0.015 mm deep) are machined around the parting line to rapidly evacuate trapped air during large-area filling, preventing scorching or blackening at the shell's edges. For slender components like fenders and long shrouds, multiple sets of balanced ejector pins and blocks are arranged to prevent bending or stress whitening caused by uneven ejection forces.

The mold is hoisted onto an 800T–1300T large-scale injection molding machine using an overhead crane, and clamping plates are tightened evenly to prevent mold opening (flashing) caused by high-pressure injection. Cooling water and mold temperature control lines are connected and checked for leaks; once confirmed leak-free, the temperature control unit is activated to pre-heat the mold for 30 minutes. The mold temperature is stabilized at 50–60°C for ASA aesthetic parts and raised to 80°C for ABS+PC alloy parts. Low-pressure mold-clamping protection parameters are calibrated so that, should residual runners or foreign objects remain during production, the mold automatically opens to prevent damage to the expensive large-scale mold. III. Complete Molding Cycle Process for the Injection Molding Machine

The complete molding cycle for the vehicle body shell comprises six major steps: mold clamping, staged injection filling, two-stage holding pressure, constant-temperature cooling, mold opening and ejection, and automatic part removal by a robotic arm. The core process strategy emphasizes low speed, low shear, and balanced filling to minimize internal molding stresses.

Mold clamping involves four stages of control: slow mold closing, rapid advance, low-pressure protection, and high-pressure locking. Given the large projected area of the shell—which generates significant mold-opening forces—high-pressure clamping is essential to ensure a tight fit at the parting line and prevent persistent flash.

Precise, staged temperature control is applied to the barrel: 170–200°C for ASA body material and 190–260°C for ABS+PC blends. Strict adherence to temperature limits is mandatory, as excessive heat causes material decomposition, yellowing, and reduced toughness. Injection filling utilizes multi-stage speed control; medium-to-high speeds are used for thin-walled areas to prevent premature melt cooling and short shots, while low speeds are employed for thick-walled bases and rib locations to reduce molecular shear stress, thereby minimizing the risk of cracking due to outdoor temperature fluctuations or paint failure during coating. Injection pressure is maintained between 90 and 120 bar; excessive pressure leads to severe flash and a sharp rise in internal stress, whereas insufficient pressure results in visible weld lines and significantly reduced impact resistance.

Once the cavity is filled, the process switches to two-stage holding pressure to compensate for plastic shrinkage during cooling. Holding times are set at 15–22 seconds for the thick-walled battery compartment and 6–10 seconds for the thin-walled decorative shell to eliminate surface sink marks. During the holding phase, the screw simultaneously prepares material for the next cycle, effectively shortening the overall molding time.

The cooling process accounts for over 60% of the total molding cycle, adhering to a standard of 3–5 seconds of cooling per millimeter of wall thickness; a body shell with a standard 2mm wall thickness requires approximately 10 seconds of cooling. Uniformly circulating cooling water continuously extracts heat from the cavity, stabilizing the mold temperature and preventing fluctuations. This ensures even cooling across the shell, preventing warping caused by uneven cooling rates and avoiding inconsistent assembly gaps in the final vehicle. After cooling, the mold opens via a three-stage slow-speed sequence, and the ejection mechanism gently releases the plastic part; a servo-driven robotic arm grips the housing while simultaneously shearing off the gate and runner scrap, transferring the finished product to the assembly line. Manual contact with the exterior surface is strictly prohibited throughout the process to prevent fingerprints or oil residue from compromising the adhesion of the subsequent spray coating.

We are a plastic body parts moulding manufacturer, providing high-quality plastic body parts moulding manufacturing. As long as you want to customize/develop plastic body parts moulding products, you can find us. We have professional injection mold design and mature manufacturing technology, providing you with one-stop service, from product design-mold making-product production-product packaging-product transportation, we can help you in every link. As long as you come to us, we will provide you with the ultimate service and satisfy you in terms of product quality, production time, information dialogue, etc.

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We are Custom Plastic Mold factory. Our factory is plastic injection mold maker. we has 17 years of experience in professional custom plastic mold and 10 years of foreign trade experience. We are custom Plastic Mold supplier. We can provide custom Plastic Mold service. Our factory can make the Injection molded plastic parts, and the quality of the products will satisfy you.

We have more than 50 high-end machines and hundreds of engineers and designers. We can provide one-stop service, from product design - mold making - product production - product packaging - transportation. We have a complete production chain. We can meet all your requirements.

Services we provide:

Professional custom mold service, Plastic mold design and manufacturing .plastic product production, product design, mold design, blow mold customization, rotational mold customization, die-casting mold customization. 3D printing services, CNC manufacturing services, product packaging, customized packaging, shipping services.

We always adhere to the principles of quality first and time first. While providing customers with the highest quality products, try to maximize the production efficiency and shorten production time. We are proud to tell every customer that our company has not lost any customer since its establishment.If there is a problem with the product, we will seek a solution actively and take responsibility to the end.

FAQ

Q1: Are you trading company or manufacturer ?

A: We are manufacturers.

Q2. When can I get the quotation?

A: We usually quote within 2 days after we get your inquiry.

If you are very urgent, please call us or tell us in your email so that we can quote for you first.

Q3. How long is the lead-time for mold?

A: It all depends on the products' size and complexity. Normally, the lead time is 25 days.

Q4. I have no 3D drawing, how should I start the new project?

A: You can supply us a molding sample, we will help you finish the 3D drawing design.

Q5. Before shipment, how to make sure the products quality?

A: If you don't come to our factory and also don't have the third party for inspection, we will be as your inspection worker.

We will supply you a video for production process detail include process report, products size structure and surface detail, packing detail and so on.

Q6. What is your payment terms?

A: Mold Payment: 40% deposit by T/T in advance, 30% second mold payment before sending out the first trial samples, 30% mold balance after you agree the final samples.

B:Production Payment: 50% deposit in advance, 50% before sending out the final goods.

Q7: How do you make our business long-term and good relationship?

A:1. We keep good quality and competitive price to ensure our customers benefit for best quality products.

2. We respect every customer as our friend and we sincerely do business and make friends with them, no matter where they come from.