Decorative Aluminum Profile Powder Coating Line

The decorative aluminum profile powder coating line is a specialized powder coating equipment system designed for decorative aluminum profiles used in architectural curtain walls, door and window frames, furniture decoration, and other fields. Its core function is to form a powder coating with uniform color, fine texture, weather resistance, and wear resistance on the surface of aluminum profiles through a refined and automated process. It not only meets decorative requirements (such as matte, frosted, metallic texture, and other appearance effects) but also adapts to the characteristics of aluminum profiles, i.e., "long length and mass production". It is a key equipment that determines the appearance and quality of decorative aluminum profiles during the manufacturing process.

I. Composition of Core Equipment

Centering on the three core requirements of "long-profile conveying, fine spraying, and color control", the coating line is mainly composed of five units:

Long-Size Conveying Unit

It adopts an overhead double-chain conveying system, where the chain span can be customized according to the length of aluminum profiles (usually 3-6 meters, and some can adapt to extra-long profiles of 9 meters). The conveying track uses high-precision guide rails to ensure no wobbling of profiles during conveying (deviation ≤ ±1mm). A servo-driven motor is equipped, and the conveying speed can be accurately adjusted (0.8-1.2m/min) to adapt to the spraying requirements of coatings with different thicknesses and avoid uneven coating caused by speed fluctuations.

Pretreatment Unit

In response to the tendency of aluminum profiles to have oxide films and oil stains attached to their surfaces, a complete process of "pre-degreasing - degreasing - alkaline etching - neutralization - water washing - chromating/non-chromium passivation - drying" is set up. Among them, the alkaline etching process uses a low-concentration alkaline solution (concentration: 3%-5%) and controls the etching amount at 5-10μm, which not only removes the surface oxide film but also avoids excessive dimensional loss of the profiles; the chromating/non-chromium passivation process forms a passivation film of 5-8μm, improving the coating adhesion and corrosion resistance; the drying process uses a hot-air circulation oven (temperature: 80-100℃, time: 15-20 minutes) to ensure the moisture content on the profile surface is < 0.1%, preventing pinholes in the subsequent coating.

Fine Spraying Unit

As the core for ensuring decorative effects, the spraying unit adopts a fully sealed spraying booth with a built-in negative-pressure dust removal system (negative pressure value: -60 to -80Pa) to prevent dust pollution from affecting the coating appearance. Multiple sets of adjustable electrostatic spray guns (usually 4-6, distributed on both sides and the top of the profiles) are equipped, and the atomized particle size of the spray guns is controlled at 60-90μm. For complex parts of the profiles, such as grooves and edges, additional side spray guns and touch-up spraying stations are added to ensure 100% coating coverage. High-end lines are also equipped with a powder color quick-switching system (color change time ≤ 15 minutes), which enables continuous production of multiple colors (such as champagne gold, fluorocarbon gray, frosted black, etc.) to meet the diverse needs of decorative aluminum profiles.

Precision Curing Unit

A long strip-shaped continuous curing oven is used (length: 20-30 meters, suitable for continuous passage of long profiles). The oven is divided into a preheating section (temperature: 120-140℃, time: 5-8 minutes), a curing section (temperature: 180-200℃, time: 20-25 minutes), and a cooling section (temperature: 100-120℃, time: 5-8 minutes). A hot-air circulation system ensures temperature uniformity within the oven (within ±3℃), avoiding color deviation of the coating on the profile surface caused by temperature differences. A temperature detection sensor is installed at the exit of the curing oven to monitor the surface temperature of the profiles in real time, ensuring complete curing of the coating (adhesion cross-cut test reaches Grade 0, pencil hardness ≥ 2H).

Post-Processing and Inspection Unit

It includes three modules: cooling, surface finishing, and appearance inspection. The cooling module uses forced air cooling (air speed: 2-3m/s) to cool the cured profiles to room temperature (avoiding profile deformation caused by high temperature); the surface finishing module uses a flexible grinding wheel (to avoid scratching the coating) to remove minor defects on the profile surface (such as particles, sagging); the appearance inspection module uses a high-intensity light inspection table (light intensity ≥ 800lux), and manual or machine vision is used to inspect the color uniformity and flatness of the coating (no defects such as orange peel, pinholes, missing spray), while sampling inspection of coating thickness (60-100μm, tolerance ±5μm) and weather resistance (salt spray resistance test ≥ 1000 hours, meeting the needs of 5-8 years of outdoor use) is also conducted.

II. Adapted Types of Decorative Aluminum Profiles

This coating line can cover most decorative aluminum profiles, mainly including:

Architectural Decorative Aluminum Profiles

Such as curtain wall aluminum profiles (complex cross-section, requiring high-precision appearance), door and window frame aluminum profiles (requiring weather resistance and anti-aging), and balcony guardrail aluminum profiles (requiring corrosion resistance and easy cleaning). The line can adapt to profiles of different cross-sectional sizes (50mm×50mm to 200mm×300mm) by adjusting the spray gun angle and conveying speed.

Furniture Decorative Aluminum Profiles

Such as wardrobe frames, desk brackets, and display rack aluminum profiles. These profiles have high requirements for coating texture (such as matte and brushed effects). The coating line can achieve special appearance effects by replacing dedicated spray guns (such as brushed powder spray guns) and adjusting curing parameters.

Industrial Decorative Aluminum Profiles

Such as elevator car decorative aluminum profiles and automotive interior aluminum profiles, which require high gloss (gloss ≥ 80°) and scratch resistance. The coating line can use high-gloss powder coatings and fine spraying processes to meet these strict requirements.

III. Core Process Flow (Taking Architectural Curtain Wall Aluminum Profiles as an Example)

Loading and Positioning

Operators hang curtain wall aluminum profiles (3-6 meters long) on the hangers of the conveying chain, ensuring the levelness of the profiles (deviation ≤ ±0.5mm). The distance between hangers is adjusted according to the width of the profiles to avoid collision between adjacent profiles.

Pretreatment

The profiles go through pre-degreasing (40-50℃, 5 minutes) → degreasing (50-60℃, 8 minutes) → alkaline etching (45-55℃, 6 minutes) → neutralization (room temperature, 5 minutes) → 3-stage water washing (room temperature, 3 minutes per stage) → non-chromium passivation (35-45℃, 5 minutes) → drying (80-100℃, 18 minutes) in sequence to ensure the surface is clean and free of oxide films.

Fine Spraying

The profiles enter the spraying booth, and 4 electrostatic spray guns (2 on each side) spray simultaneously. The electrostatic voltage is 70-80kV, and the powder output is 80-100g/min. For the groove parts of the profiles, the angle of the side spray guns is adjusted to 45° to ensure uniform coating coverage. When producing champagne gold profiles, the powder color quick-switching system prepares the corresponding powder in advance, and after color change, the purge system cleans the residual powder in the pipeline to avoid color mixing.

Continuous Curing

The sprayed profiles enter the curing oven and complete preheating, curing, and cooling according to the preset temperature curve. After exiting the oven, they undergo temperature detection (surface temperature ≤ 40℃) before entering the cooling process.

Post-Processing and Inspection

After cooling, the profiles undergo surface finishing to remove minor defects, then pass through the high-intensity light inspection table for appearance inspection. Qualified profiles are packaged, while unqualified profiles (such as color deviation and coating defects) are marked and sent to the rework area. A low-temperature paint stripper is used for paint removal before they re-enter the production line.

IV. Application Scenarios

Large-Scale Decorative Aluminum Profile Manufacturers

For example, architectural aluminum profile manufacturers with an annual output of over 100,000 tons adopt fully automatic decorative aluminum profile powder coating lines to realize the fully automated process of "loading - pretreatment - spraying - curing - inspection - unloading". The daily production capacity can reach 5,000-8,000 meters, meeting the needs of mass orders.

Small and Medium-Sized Customized Aluminum Profile Manufacturers

To meet the needs of multi-variety and small-batch production (such as customized furniture aluminum profiles), semi-automated coating lines (manual touch-up spraying + automatic curing) are adopted. These lines allow flexible adjustment of the production rhythm and low color change costs, adapting to the rapid delivery of customized orders.

Aluminum Profile Renovation Enterprises

For the renovation needs of old architectural curtain walls and door/window profiles, a combination of small manual spraying modules and curing ovens is adopted. Through enhanced pretreatment (such as paint removal and rust removal) and fine spraying, the appearance of old profiles is upgraded, extending their service life.

V. Core Advantages

Excellent Decorative Effects

Through fine spraying and precise curing, the coating has uniform color (color difference ≤ ΔE1.0) and fine texture. It can achieve various decorative effects such as matte, frosted, and metallic luster, meeting the aesthetic needs of different scenarios.

Strong Adaptability

The conveying speed, spray gun parameters, and curing temperature can be flexibly adjusted to adapt to decorative aluminum profiles of 3-9 meters in length and different cross-sectional sizes. At the same time, it supports quick switching of multiple colors, responding to the diverse market demands.

Weather Resistance and Durability

The cured coating has excellent weather resistance (UV resistance, acid rain resistance), corrosion resistance (salt spray resistance ≥ 1000 hours), and scratch resistance (pencil hardness ≥ 2H). It shows no obvious fading or chalking after 5-8 years of outdoor use.

Environmental Protection and High Efficiency

Powder coatings are used (no solvent volatilization, VOC emissions are much lower than those of paint), and a powder recovery system is equipped (recovery rate ≥ 95%), which not only meets environmental protection standards but also reduces coating costs. The fully automated line increases per capita production capacity by more than 30%, achieving high production efficiency.