The automotive painting process is a technology that requires extremely high environmental conditions. As a key factor affecting the performance of the paint film, temperature directly affects the leveling, gloss and anti-aging ability of the paint surface. Mastering painting techniques under different temperature conditions is the core of ensuring paint quality:
1、 Key points of spray painting in low-temperature environment
When the outdoor temperature is below 20 ℃, the drying speed of paint slows down significantly, and defects such as sagging and orange peel are prone to occur. At this point, the following measures should be taken:
Environmental control: It is recommended to control the temperature between 15-25 ℃ and maintain the humidity within the range of 40% -60%. Heating equipment can be used to increase the ambient temperature and avoid surface temperature fluctuations exceeding 3 ℃.
Spray gun adjustment: Maintain a distance of 15-20cm between the spray gun and the workpiece, and use low air pressure (1.5-2.0bar) and wide fan surface (70% -80%) during spraying.
Paint selection: Choose low-temperature curing primer and topcoat, combined with quick drying diluent. The spraying thickness of each layer should not exceed 30 μ m, and the interlayer should be dried for 24 hours.
Equipment assistance: Use a hot air gun to preheat the local area, with a temperature controlled at 60-80 ℃ to avoid discoloration of the paint film.
2、 Spray painting strategies in high temperature environments
When the temperature exceeds 30 ℃, rapid solvent evaporation can cause defects such as pinholes and fish eyes. At this point, the following measures should be taken:
Sunshade protection: Use a sunshade net or mobile workshop to avoid direct sunlight and maintain a temperature between 30-40 ℃.
Diluent adjustment: Increase the proportion of slow drying diluent and use slow drying curing agent. Control the pressure between 2.5-3.0 bar during spraying and use a multi pass thin spraying method.
Construction time selection: Avoid the high temperature period at noon and choose the low temperature period in the morning and evening for construction. The spraying thickness of each layer is controlled within 25 μ m, and the interlayer drying time is shortened to 8 hours.
Forced ventilation: Use strong ventilation equipment to control the dew point temperature to be 3 ℃ lower than the surface temperature of the workpiece.
3、 The optimal spraying solution for standard environments
20-25 ℃ is the ideal spraying temperature range. At this moment:
Temperature control: Ensure that temperature fluctuations do not exceed 2 ℃ and humidity remains around 50%.
Spray parameters: spray gun distance of 18cm, air pressure of 2.2bar, fan surface of 80%, spray angle perpendicular.
Process flow: Spray 2 coats of primer (thickness 60-80 μ m) first, and dry each layer for 4 hours; Spray 3 coats of topcoat (thickness 90-120 μ m), and dry each layer for 6 hours.
Equipment selection: Use two-component high-pressure airless spraying equipment, and use original matching products for paint.
4、 Strategies for coping with special climate conditions
During the rainy season when the humidity exceeds 80%, dehumidification equipment should be added to control the humidity below 65%. Construction in foggy weather needs to be suspended until the humidity drops below 70% before resuming. During winter construction, it is recommended to use antifreeze solvents, preheat the paint to 25 ℃ before spraying, and maintain a constant temperature of 50-60 ℃ during the curing process.
In practical operation, technicians should dynamically adjust the construction plan based on real-time environmental parameters to ensure that the paint surface achieves the best visual effect and protective performance.
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