US Patent 10259012 Sifting screen

The invention relates to a screen frame adapted for use in a shaker and to which woven wire mesh is to be attached, comprising an outer perimeter and a plurality of plastics ribs extending between opposing regions of the perimeter, the frame being arranged such that, when fitted in a shaker to which it is adapted for, a portion of the opposing regions is clamped in place and a portion of the opposing regions is not clamped with the number of plastics ribs per unit length for the clamped portion greater than the number of plastics ribs per unit length for the unclamped portion, and to a shaker comprising at least one such screen frame.