코팅 산업에서 에어 나이프를 선택하는 방법 Shenzhen QX가 도움이됩니다.

In the coating industry, the air knife is a key device used to control coating thickness, uniformity, and drying/cleaning. Its performance directly affects coating quality (such as edge effects, orange peel patterns, and other defects). The following are the key design points and selection considerations for the air knife system:

1. The core role of the air knife

Coating thickness control:

scrape off excess coating through high-speed airflow to achieve precise film thickness (such as lithium battery electrode coating).

Drying assistance: 

accelerate solvent evaporation (such as solvent-based coating or UV curing pre-treatment).

Surface cleaning: 

blow away substrate dust and debris (such as pre-treatment before thin film coating).

2. Key parameters of air knife design

(1) Airflow uniformity

Air outlet structure:

Narrow slit design: The slit width is usually 0.1~2mm, and the full-width airflow velocity difference must be ≤5% (such as ±1% required for lithium battery coating).

Internal flow stabilization structure: add a guide plate or honeycomb rectifier to avoid turbulence causing coating stripes.

Wind pressure and wind speed:

Generally, the wind speed requirement is 20~100m/s (higher wind speed is required for high viscosity slurry), and the wind pressure range is 0.2~1.5Bar.

(2) Material selection

Corrosion resistance:

When in contact with solvents, stainless steel 316L or titanium alloy (such as NMP solvent coating) should be used.

Aluminum alloy (lightweight) or engineering plastic (anti-static) can be used in ordinary environments.

Abrasion resistance: When the slurry contains particles (such as ceramic coating), surface hardening treatment is required (such as tungsten carbide coating).

(3) Installation angle and distance

Angle: Usually 30°~45° to the substrate (too large an angle will cause rebound and splashing, too small an angle will result in insufficient scraping force).

Distance: 5~20mm (the closer the distance, the higher the control accuracy, but it is necessary to avoid scratching the substrate).

3. Special requirements of the coating industry

(1) High-precision coating (such as lithium battery pole pieces)

Multi-stage wind knife system:

Sectional independent control of wind pressure to compensate for edge thickness differences caused by substrate tension fluctuations.

Temperature-controlled air knife: Heated airflow (50~80℃) accelerates solvent evaporation and reduces drying energy consumption.

(2) Wide-width coating (such as photovoltaic backplane)

Segmented air knife splicing:

When the width is greater than 1m, multiple air knives need to be seamlessly connected to avoid uneven coating at the joints.

Dynamic adjustment system:

Cooperate with real-time feedback from sensors to automatically adjust the air pressure (such as ultrasonic thickness gauge linkage).

(3) Flexible substrates (such as diaphragms, PET films)

Low-impact design:

Reduce wind speed (<30m/s) and increase the air outlet angle to prevent the substrate from shaking or deforming.

Static elimination:

Integrated ion rod to prevent the film from adsorbing dust due to static electricity.

4. Common problems and solutions

Problem	Cause	Solution
Coating edge is too thick	Airflow leaks at both ends of the air knife	Install end plates or adjustable baffles
Longitudinal stripes	Internal contamination or deformation of the air knife	Clean/replace the air knife regularly and check the steady flow structure
Substrate shaking	Air pressure is too high or the angle is improper	Reduce the air pressure to 30m/s and adjust to 40° angle
Solvent residue	Insufficient drying efficiency	Use heated air knife or increase post-drying

5. Selection suggestions

Clear process requirements:

Coating type (solvent/water-based), substrate (metal foil/film), precision requirements (μm level).

Customized design:

Communicate with suppliers about details such as air knife length, material, and temperature control function.

System integration test:

Verify airflow uniformity (such as smoke test) and coating effect in a simulated environment.

High-end application example: In the double-layer coating of lithium batteries, the air knife needs to be used in conjunction with a comma scraper, scraping first and then blowing to ensure that the surface density consistency is ≤±1.5%.

By optimizing the air knife parameters, coating defects can be significantly reduced, yield can be improved and energy consumption can be reduced.

6. About Shenzhen Qixingyuan Machinery Equipment Co., Ltd.

Shenzhen Qixingyuan Machinery Equipment Co., Ltd. has been specializing in the production of air knives for more than 10 years. Our eagle beak air knife is widely used in the coating industry and has always gained a good reputation. The unique design of the eagle beak air knife makes it perfectly adapted to the requirements of the coating industry.