Plastic molding machine 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 molding machine 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 molding machine parts moulding products, we can make corresponding plastic parts, which is mainly done through injection molds.

Plastic components for injection molding machines include exterior protective panels, guards for hydraulic/motor assemblies, flame-retardant electrical housings, operation panel casings, wear-resistant handles, cooling water connectors, safety baffles, dust covers for material hoppers, and limit switch bases. These parts operate in environments characterized by high-temperature oil mist, hydraulic oil exposure, vibration, and heat dissipation from the equipment. Electrical components require flame retardancy and insulation, while structural parts demand oil resistance, vibration resistance, and dimensional stability. Key materials include flame-retardant ABS, reinforced PA6, modified PP, PC/ABS alloys, and wear-resistant POM. Molding processes focus on five critical performance indicators: resistance to machine oil, low internal stress, stable flame retardancy, wear resistance (without deformation), and high-temperature resistance. Production guidelines cover the entire workflow, including raw material pretreatment, mold design, injection molding parameters, post-processing, and defect control.

I. Key Points for Material Selection and Pretreatment

1. Material Selection and Classification

1) Operation panels and exterior machine covers: PC/ABS alloy—offers heat resistance, impact resistance, and paintability; withstands high surface temperatures and resists cracking under prolonged vibration.

2) Electrical control box housings, wiring protection boxes, and switch bases: Flame-retardant ABS—V0 flame-retardant rating, insulating properties to prevent short circuits, and compliance with electrical safety standards for machine tools.

3) Wear-resistant handles, clips, sliders, and quick-connect fittings: Glass fiber-reinforced PA6 and POM—low friction coefficient, wear resistance, and hydraulic oil resistance; withstands tens of thousands of opening/closing cycles without significant wear.

4) Large machine dust guards and baffles: High-rigidity modified PP—low cost, resistance to acidic/alkaline cutting fluids, and short molding cycles.

5) Transparent safety viewing windows: High-impact PC—protects against high-temperature splashes of molten material from the screw.

Strict control of material recycling: The addition of regrind (sprue/runner scrap) is strictly prohibited for flame-retardant electrical parts and wear-resistant load-bearing components, as regrind compromises flame-retardant systems and significantly reduces wear strength. For exterior guards, the regrind addition ratio must be ≤10% and mixed only with virgin material of the same type. When blending materials, oil-resistant, low-migration mold release agents and heat-aging resistant masterbatches must be added to withstand prolonged exposure to high temperatures and hydraulic oil, thereby preventing issues such as oil exudation, surface whitening, and embrittlement. Flame-retardant raw materials, glass-fiber reinforced nylon, and standard plastics must be mixed and stored in separate bins; cross-contamination of materials is strictly prohibited.

2. Key Points for Mixing Operations

Use a vertical mixer at low speed (under 300 rpm) for 6–12 minutes. Do not mix glass-fiber reinforced nylon at high speeds, as this can break the glass fibers and compromise rigidity. For flame-retardant ABS, avoid prolonged friction that generates heat, as this can cause the flame retardant to decompose prematurely and lose effectiveness. Once mixing is complete, seal the mixing vessel to protect the raw materials from contamination by workshop oil mist and dust.

3. Strict Drying and Dehumidification Standards

PC, PC/ABS, and PA6+GF are highly hygroscopic; molding with excessive moisture content leads to "silver streaks" and internal voids, causing the parts to crack along these voids when subjected to stress or vibration.

PC/ABS panels: Hot-air drying at 90°C for 4–5 hours (moisture content ≤0.04%);

Glass-fiber PA6 wear-resistant parts: Dehumidifying drying at 110°C for over 4 hours; materials must be re-dried if the machine is idle for more than 30 minutes;

Flame-retardant ABS: Drying at 80°C for 3 hours;

PP: Drying at 60°C for 1 hour to remove moisture only during the rainy season; no drying is required for standard production.

After drying, transport materials to the machine via sealed piping to prevent re-absorption of moisture or oil mist from the workshop air.

II. Key Points for Mold Design and Production

The injection-molded parts fall into two categories: large, thin-walled protective housings and small, precision wear-resistant structural components. Mold design focuses on wear and erosion resistance, balanced cooling, prevention of oil exudation, and high-strength ejection capabilities. **Mold Steel Selection**

For the cavities of PC/ABS and flame-retardant ABS housings, 718H mirror-finish pre-hardened steel is selected to ensure a smooth surface suitable for painting. Molds for glass-fiber reinforced nylon and POM wear-resistant parts undergo nitriding to withstand continuous erosion from glass fibers and hard fillers, thereby extending service life. S136 corrosion-resistant mirror steel is used for small precision switch bases to resist corrosion from hydraulic fluids and moisture. All corners feature radiused designs (R-fillets) to eliminate stress concentrations and prevent cracking caused by equipment vibration.

**Cooling System Design (Key to Controlling Warpage and Surface Defects)**

Housing walls are 1.8–2.5 mm thick, while mounting bosses and ribs are 4–6 mm thick; significant thickness variations can easily lead to warpage and surface defects like "blooming" (oil/additive exudation). The mold utilizes conformal cooling channels, with spiral cooling cores installed in thick-walled bosses to ensure balanced cooling. Mold temperatures are controlled by zone: 70–80°C for PC/ABS; 50–60°C for flame-retardant ABS; 80–90°C for glass-fiber nylon; and 30–40°C for modified PP housings. High mold temperatures for nylon increase crystallinity, enhancing wear and oil resistance; high temperatures for PC reduce internal stress, preventing cracking in high-temperature operating environments.

**Venting and Ejection Optimization**

Large housings involve long melt flow paths; continuous venting slots (0.012–0.015 mm deep) are machined around the parting line to exhaust high-temperature decomposition gases, preventing black spots and odors. For wear-resistant sliders and small precision bases with dense ribbing, multi-point symmetrical ejector pins and sleeve ejectors are used to prevent deformation or stress marks ("whitening") caused by uneven ejection force. Auxiliary ejector blocks are added for slender safety baffles to prevent bending during demolding.

**Mold Installation and Assembly Specifications**

Molds for large housings are designed for 400T–700T injection molding machines; clamping plates are tightened evenly to prevent extensive flash during high-pressure injection. Install flow detectors on all water circuits to ensure unobstructed flow; calibrate low-pressure mold protection to prevent residual sprue material from damaging the mold cavity; and conduct comprehensive leak testing on water connections to prevent moisture from contaminating the melt and causing bubbles. Before producing flame-retardant parts, thoroughly clean the barrel and mold to remove any residual material from previous runs.

III. Key Points of the Injection Molding Process

Process Core: Low temperature and low shear, staged holding pressure, and adequate cooling; balancing flame-retardant stability, wear resistance, and resistance to oil and vibration.

Precise zoned temperature control of the barrel

PC/ABS control panels: 190–250°C; nozzle below 260°C (excessive heat causes degradation and reduces heat resistance).

Flame-retardant ABS electronic housings: 170–220°C; maximum 230°C (high temperatures destroy the flame-retardant system, causing a loss of fire-resistant properties).

Glass-fiber reinforced PA6 wear-resistant parts: 230–260°C; do not exceed 270°C (nylon decomposition causes voids and a drastic drop in strength).

Modified PP protective covers: 190–220°C.

Staged injection filling control

Large protective covers use three-stage variable-speed filling: low-speed buffering at the gate, medium-to-high speed filling in the middle section, and reduced speed at the distal weld line to minimize internal shear stress and prevent cracking caused by thermal cycling. Small wear-resistant nylon parts are filled at a steady, low-to-medium speed to reduce fiber exposure and improve the flatness of wear surfaces. Injection pressure: 85–120 bar; insufficient pressure results in weak weld lines prone to fracture under vibration, while excessive pressure creates high internal stress, leading to whitening and cracking upon contact with hydraulic oil.

Two-stage holding pressure

Crystalline materials like PP and PA6 exhibit significant shrinkage; set primary and secondary holding pressure stages to compensate for this. Holding times are 6–10 seconds for thin-walled covers and 15–22 seconds for thick-walled wear-resistant bases and mounting brackets to eliminate surface sink marks. Material plasticization (recovery) occurs simultaneously during the holding phase to shorten the molding cycle. Cooling and Part Removal Specifications

Cooling time is set at 3–5 seconds per 1 mm of wall thickness; 2 mm shields require 9–12 seconds of cooling. Insufficient cooling leads to ongoing deformation when the plastic parts are later exposed to high equipment temperatures and oil contamination. Mold opening and ejection must proceed at a slow, steady speed. Parts are removed by a robotic arm and laid flat on a fixture table; stacking or compressing hot plastic parts is prohibited to prevent permanent warping.

IV. Post-Processing, Shaping, and Supplementary Machining

Injection-molded parts are frequently exposed to oil; surface burrs and residual stress can significantly shorten their service life, so post-processing steps must not be skipped.

Gate and Burr Trimming

Use a cutting machine to trim large cold-runner gates flush. Use diamond grinding bits to precisely remove fine flash from sliding surfaces and snap-fit areas, ensuring smooth movement without binding. Ensure the interior of electrical housings is free of sharp burrs to prevent damage to wire insulation. Glass-fiber reinforced nylon is too hard for standard sandpaper; use specialized grinding bits for polishing.

Annealing for Stress Relief

Before painting, PC/ABS and flame-retardant ABS cosmetic parts and electrical housings undergo constant-temperature annealing in an oven at 70°C for 2–3 hours. This slowly releases internal stress, preventing paint peeling or housing cracking caused by high operating temperatures and oil exposure. PP shields do not require annealing; small glass-fiber nylon parts may undergo low-temperature, short-duration annealing to improve oil resistance. Slightly warped shields are heat-shaped in metal fixtures to ensure uniform assembly clearances.

Surface Treatment

Protective covers may be coated with oil-resistant industrial paint; prior to coating, use electrostatic cleaning to remove oil, dust, and mold release agent residues. Transparent PC viewing windows undergo UV hardening to prevent scratching by high-temperature molten material. After grinding, electrical flame-retardant parts undergo sampling tests for insulation and flame retardancy; only compliant parts proceed to the next stage. Oil mist is isolated throughout the workshop to prevent premature oil contamination of semi-finished parts. V. Key Control Points for Common Defects

Flame-retardancy failure in electrical housings: Flame-retardant material mixed with regrind or barrel overheating; process flame-retardant material separately and strictly control the upper limit of processing temperature.

Premature whitening/wear on wear-resistant sliders: Failure to use glass-fiber reinforced nylon or POM, or insufficient crystallization due to low mold temperature; switch materials and increase mold temperature.

Whitening and cracking of plastic parts upon contact with hydraulic oil: Excessive internal stress or insufficient raw material drying; add an annealing step and strictly dry the raw materials.

Warpage and assembly misalignment of machine body guards: Asymmetrical cooling channels or excessively high mold temperature for PP; optimize for symmetrical cooling and perform post-molding thermal reshaping.

Internal bubbles in transparent viewing windows: Inadequate dehumidification of PC; extend the dehumidification/drying time at 110°C and ensure the hopper is sealed against moisture.

We are a plastic molding machine parts moulding manufacturer, providing high-quality plastic molding machine parts moulding manufacturing. As long as you want to customize/develop plastic molding machine 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.