Abstract: In one embodiment of the present invention, a method of affixing a screen sub-assembly to a substrate includes the steps of depositing a thermoplastic material on a surface of the substrate and placing the screen sub-assembly on top of the substrate. The screen sub-assembly includes a screen element and a thermoplastic material. The method also includes the steps of placing the screen sub-assembly and the substrate on a movable surface and driving the movable surface across a base support surface so as to position the screen sub-assembly and the substrate below an ultrasonic welding device. The ultrasonic welding device is actuated to emit ultrasonic energy that results in the screen sub-assembly being affixed to the substrate. The substrate can be formed of a perforated metal plate and a coating of thermoplastic powder.

Abstract: A screen assembly for a vibratory screening machine including a frame, and a screen cloth on the frame having wires with a diameter D of between about 1.6.times.10.sup.3 micrometers and 17.8 micrometers with a peak to valley roughness R in micrometers which is between about R=0.333D and R=0.05D. A screen cloth for mounting on the frame having a range of dimensions as set forth above. A method of making a screen for a vibratory screening machine including the steps of providing a screen cloth having a wire of a diameter D of between about 1.6.times.10.sup.3 micrometers and 17.8 micrometers and roughing the surface of the wires to a peak to valley roughness which is between about R=0.333D and R=0.05D.