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A methodology is developed that incorporates high resolution CFD flowfield information and a particle trajectory simulation, aimed at addressing Paint Transfer Efficiency (PTE) for bell sprayers. Given a solid model for the bell sprayer, the CFD simulation, through automeshing, determines a high resolution Cartesian volume mesh (14-20 million cells). With specified values of the initial shaping air, transient and steady-state flow field information is obtained. A particle trajectory visualization tool called SpraySIM uses this complicated flowfield information to determine the particle trajectories of the paint particles under the influence of drag, gravity and electrostatic potential. The sensitivity of PTE on shaping air velocity, charge-to-mass ratio, potential, and particle diameter are examined.

In this paper we discuss the development of a paint applicator system test protocol developed by Ford Motor Company. The test protocol involves spraying commercially available automotive primers, basecoats and clearcoats with known characteristics onto 90 cm long by 30 cm wide phosphated panels (36 in by 12 in) at application conditions necessary to obtain a typical range of film builds. The film builds are then measured at frequent intervals to obtain build averages, standard deviations, and spray pattern sizes. From these, transfer efficiency and pattern uniformity are obtained. In addition, the quality of the applied paint is measured at well defined film builds using several instruments to determine whether the application system being tested is capable of achieving the superb appearance demanded by our customers. Details of the required test matrix, the measurement templates and some comparative results obtained using the Ford protocol will be presented.