Distortion of the Image by the Screen Printing Process

A systematic investigation of the influence of the screen printing process parameters has been undertaken. The investigation examined the image distortion by both analytical and experimental means. A cylinder press was fully instrumented with a customized squeegee system which allowed the tip forces, angles and hardness to be varied independently. An orthogonal array was designed which allowed 8 parameters to be fully investigated using only 18 experiments. The test sheet was composed to allow the measurement of distortion by reference to crosshairs and graduated scales on the sheet. The distortion was measured across the whole sheet using an engineering measuring machine. The investigation found that the experimental measurements tie up well with the analytical models, although there is considerable interaction between the distortion in the two orthogonal directions which deviates the behavior from the 2 dimensional analytical models. The image distortion was found to be governed by the screen - squeegee friction characteristics, which is controlled by a number of press parameters. A finite element model of the screen distortion has been developed as a result of the investigation.