Undulating screen for vibratory screening machine

A screening screen assembly for a vibratory screening machine comprising an apertured frame, an undulating subassembly of a support screen and a fine screening screen having ridges and troughs, peaks on said ridges, sides on said ridges between said peaks and said troughs, a fused plastic grid bonding said fine screening screen to said support screen at spaced locations while leaving unobstructed portions of said screens therebetween, undersides on said troughs bonded to said apertured frame, said fused plastic grid including first portions extending substantially perpendicularly to the length dimension of said ridges through said peaks and throughout the major portion of said sides of said ridges, and said fused plastic grid also including second portions which extend transversely of said first portions and extend through spaced portions of said troughs while leaving unobstructed portions of said troughs therebetween.