| Résumé : |
The French automotive industry has improved the control of powder flow in the fluidisation bed thanks to a new measuring system.
As margins in the automotive industry come under increased pressure, companies are looking to optimise processes and save money in every aspect of their manufacturing. In addition, many car manufacturers see the introduction of innovative technologes as a key strategy in their efforts to stay ahead of the competition.
Finishing and powder coating is a critical process in automotive manufacturing and one where cost optimisation and innovation are key.
To achieve a high-quality finish from a powder coating, complete and accurate information about powder flowability is essential.
A powder coating must be free-flowing and it must fluidise well in the fluidisation bed. This ensures that individual particles are separated, improving the electrostatic charge that can be applied to the powder so that flow more easily through the spray gun to give an even finish. The flowability of a powder is also important in powder recovery - a free-flowing powder will not clump during recovery, reducing the amount of waste.
Automotive powder coatings are a mixture of several components, such as resin, crosslinker, pigments, flow aids and degassing solvent. Their flowability is affected by many factors, most being especially sensitive to moisture adsorption and exposure to heat, for example. The way they are stored can also have a large impact on their subsequent performance in the spray painting booth.
Smooth fluidisation is a key goal, and the ability to achieve this depends on finding the optimal balance of critical parameters such as particle shape, size distribution, flow characteristics, moisture content, air velocity, humidity and ratio of powder depth to the bed floor area.
A powder rheometer can quantify a powder's flowability under a range of conditions and give valuable information about how it will perform in a fluidised bed. |
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Blade runner in POLYMERS PAINT COLOUR JOURNAL - PPCJ, Vol. 194, N° 4481 (10/2004)
