The ink transfer process was analyzed and a shear force model was established. The shear force decreases when the angle between printing direction and the printed line increases. This effect is more significant when thin lines are printed. Lines with width of 30 and 80 micrometers were printed to verify the shear force model. The result showed that the cross sectional areas of printed lines decrease when the print angle increases, and the 30-micrometer-wide lines suffer more from this effect. The model was optimized based on experiment result to improve its accuracy.