Automotive manufacturing humidification Car manufacturing humidity issues
The optimum humidity for the transfer of paint from the spray gun to car body work is 72%rH. This prevents any evaporation of the water-based paint and allows the paint to reach the bodywork as the manufacturer intended.
By humidifying correctly paint casts are reduced by avoiding evaporation.
A major automobile manufacturer has increased the number of cars passed first time from the paint spray booths, without any sanding required, by 8% due to improving their humidity control.
As paint spray booths are fed air from a central air conditioning system the type of humidifier used is an in-duct unit. Historically this has been a spray washer system but a more modern solution is an evaporatetive humidifier, as the running costs are much lower and it provides totally hygienic humidification.
The optimum humidity to eliminate static in sand decks is 55%rH. At this level the moisture content of the air changes the electrical charge of the dust so that it is the same as the surface of the car. This results in the dust running off the bodywork of the car instead of being attracted to it. This greatly decreases the sanding time and improves the quality of the finish.
By using a direct-air spray humidifier up to 4℃ of evaporative cooling can be achieved around the sand decks. This is a very beneficial side-effect as these areas can reach up to 40℃ under the hot inspection light and with painted surfaces that have recently been through an oven
To design cars that are suitable for global use, in a range of humidities and temperatures, the engine must be able to operate in such conditions. Humidifiers that can recreate any such conditions are an essential element of the air conditioning plant feeding these areas.
As close control of humidity is required the most popular form of humidifier for this application is a steam generating system. Although in some circumstance, a spray system can be used, giving considerable savings in running costs.
Formula One engines are precisely tuned to the humidity of the country they will be racing in using very close control humidifiers. Typically these will be steam systems run on reverse osmosis water.