Exhaust fan 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 exhaust fan moulding 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 exhaust fan moulding moulding products, we can make corresponding plastic parts, which is mainly done through injection molds.

As a common ventilation appliance in kitchens and bathrooms, the injection-molded components of an exhaust fan primarily consist of core parts such as the front panel, grille, impeller frame, motor mount, air guide ring, and rear cover. These products typically feature thin-walled structures with multiple reinforcing ribs and numerous assembly holes; consequently, they must not only ensure a flat, flawless exterior appearance but also satisfy requirements regarding assembly precision, structural integrity, and long-term resistance to heat and grease-laden fumes. The injection molding process demands meticulous execution across various stages—including material selection, mold design, process control, and defect prevention. The following details the complete molding procedure and highlights key technical considerations.

I. Raw Material Selection and Drying Treatment

The primary materials used for injection-molded exhaust fan components are PP, ABS, and reinforced PP. Specific grades are selected based on the distinct functional requirements of each component to ensure an optimal balance between moldability and in-service performance.

For aesthetic components—such as the front panel and grille—high-gloss ABS is the preferred choice due to its excellent rigidity, fine surface finish, and ease of coloring. It exhibits a stable shrinkage rate of 0.4%–0.7% and is processed at a molding temperature of 220–260°C, making it ideally suited for complex curved surfaces and intricate textures. Structural load-bearing components—such as the motor mount and frame—typically utilize modified PP or glass-fiber-reinforced PP. These materials offer low cost, superior toughness, and resistance to heat and grease; they feature a shrinkage rate of 1.2%–2.0% and are molded at temperatures ranging from 190°C to 220°C. For specific components requiring exceptional strength, the addition of 10%–20% glass fiber reinforcement is employed to enhance rigidity and resistance to deformation. Heat-resistant components—such as the air guide ring and rear cover—may be fabricated using heat-resistant ABS or heat-resistant PP to ensure that they remain free from softening or deformation during prolonged operation.

Proper pretreatment of raw materials serves as the fundamental basis for preventing cosmetic defects. ABS and heat-resistant ABS exhibit significant hygroscopicity; therefore, they must undergo hot-air drying at a temperature of 80–90°C for 3–4 hours. The moisture content must be strictly controlled to remain below 0.03% to prevent the occurrence of silver streaks, bubbles, or surface haziness during the molding process. PP material, conversely, possesses low hygroscopicity and generally does not require rigorous drying; however, if the material has been stored in a humid environment, it may be dried at 70°C for one hour to eliminate any surface-adhering moisture. For color matching, specialized color masterbatches are utilized at an addition ratio of 2%–4%. The mixture is thoroughly blended before being fed into the molding machine, ensuring that all products within the same batch are free of color variations or speckles.

II. Key Design Considerations for Mold Structure

Plastic components for exhaust fans typically feature thin walls, multiple perforations, deep cavities, and reinforcing ribs; consequently, the mold design directly determines molding stability and product yield.

The parting line is typically positioned at the point of the product's maximum contour, avoiding visible exterior surfaces to minimize the aesthetic impact of the mold parting line. The mold cavity and core employ a modular insert structure to facilitate machining and maintenance; their surfaces are polished to a roughness of Ra < 0.05 μm to ensure the high gloss finish required for aesthetic components. The thickness of reinforcing ribs is controlled at 50%–60% of the main wall thickness to prevent sink marks or depressions caused by excessively thick ribs. Assembly holes and snap-fit features utilize insert pins or slider mechanisms to ensure precise positioning and smooth demolding.

The gating system typically employs a hot runner combined with side gates or pin-point gates. For large panels, multi-point gating is utilized to ensure rapid and uniform melt filling, thereby minimizing weld lines. Runner diameters range from 5 to 8 mm, and gate dimensions range from 0.8 to 1.2 mm; gate locations are strategically concealed to avoid compromising the product's aesthetic appeal. The cooling system features a uniformly distributed network of circulating water channels, with cooling lines—typically 8–10 mm in diameter—embedded in both the cavity and the core. The mold temperature is maintained between 40°C and 70°C to ensure rapid and uniform cooling, thereby shortening the molding cycle and reducing internal stresses.

The venting structure is of critical importance. During the filling process, the molten material is prone to trapping air within deep cavities, at the ends of reinforcing ribs, and in corner regions, potentially leading to defects such as short shots, burn marks, or voids. Consequently, the mold must incorporate vent grooves—typically 0.02–0.03 mm deep and 1.5–2 mm wide—within these air-trap-prone areas. These grooves work in conjunction with the natural venting gaps at the parting line to ensure the efficient evacuation of air from the mold cavity. When processing glass-fiber-reinforced materials, the vent grooves must be made slightly wider to prevent glass fibers from clogging the venting channels. III. Injection Molding Machine Selection and Core Process Parameters

Plastic components for exhaust fans are predominantly small to medium-sized parts. Consequently, horizontal injection molding machines with a clamping force ranging from 160 to 500 tons are selected. The injection volume is matched to be 1.2 to 1.5 times the single-part weight to ensure adequate plasticization and stable injection. Core process parameters are controlled in stages, focusing on four key elements: temperature, pressure, speed, and time.

Barrel temperatures are set using a gradient profile. For ABS material, the front section of the barrel is set to 240–260°C, the middle section to 230–250°C, and the rear section to 210–230°C; the nozzle temperature is kept slightly lower—by 5–10°C—to prevent drooling. For PP material, barrel temperatures are set to 210–220°C for the front section, 200–210°C for the middle section, and 180–190°C for the rear section; temperature fluctuations are maintained within ±5°C to prevent material degradation and discoloration. Mold temperatures are controlled at 50–70°C for ABS to enhance surface gloss, and at 40–60°C for PP to balance crystallization shrinkage and minimize warping.

Injection pressure is set based on wall thickness and structural complexity: 80–120 MPa for ABS, and 90–140 MPa for PP; for glass-fiber-reinforced PP, the pressure is increased appropriately. Injection speed is controlled in stages: an initial low-speed phase prevents jetting; a mid-phase high-speed phase fills the main body of the part to minimize weld lines; and a final low-speed phase concludes the injection to prevent air entrapment and flashing. Holding pressure is set at 60–70% of the injection pressure, with a holding time of 10–20 seconds—continuing until the gate freezes—to compensate for shrinkage and eliminate sink marks. Back pressure is maintained at 3–6 MPa to improve the uniformity of the melt plasticization.

The cooling time constitutes the major portion of the molding cycle. For cosmetic parts, cooling lasts 20–35 seconds; for structural parts, it lasts 15–25 seconds. The criterion for determining cooling duration is that the product can be ejected without deformation or sticking to the mold. The total molding cycle is typically controlled within a range of 35–60 seconds, balancing both production efficiency and product quality. Ejection is achieved using ejector pins, ejector plates, or pneumatic mechanisms to prevent "ejector whitening" and cracking; for parts with multiple holes, sleeve ejection is employed to ensure the roundness and integrity of the hole features.

IV. Post-processing and Quality Inspection

Following molding, products undergo simple post-processing. The gate runners are trimmed away, and tools or ultrasonic equipment are used to remove flash and burrs, ensuring the parts are safe to handle. Certain ABS cosmetic parts may undergo an annealing process, involving a soak in a 70°C oven for 1 to 1.5 hours to relieve internal stresses and prevent cracking during subsequent assembly.

Quality inspection is categorized into three areas: appearance, dimensions, and performance. Appearance inspections verify the absence of sink marks, voids, weld lines, color variations, ejector whitening, and scratches, while ensuring uniform surface gloss. Dimensional checks are performed using calipers or a Coordinate Measuring Machine (CMM), with a primary focus on controlling assembly hole spacing, snap-fit dimensions, and the flatness of mating surfaces; tolerances are generally maintained within ±0.1 mm. Regarding performance, simple drop tests and snap-fit fatigue tests are conducted to ensure structural integrity and reliability; heat-resistant parts also undergo high-temperature static tests, requiring them to remain free of significant deformation after being held in a 70°C environment for 24 hours.

We are a exhaust fan moulding moulding manufacturer, providing high-quality exhaust fan moulding moulding manufacturing. As long as you want to customize/develop exhaust fan moulding 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.