Abrasive flow machining with an in situ viscous plastic medium

A method of treating a workpiece to work selected surfaces and edges thereof, comprising the steps of:

• providing a displacer member adjacent to said workpiece, said displacer member having surfaces in a facing, spaced relationship substantially conforming to the surfaces of said workpiece to be abraded to thereby form a media chamber between the surfaces of said workpiece to be worked and said displacer member;
• introducing an abrasive medium into said media chamber, said abrasive medium comprising a visco-elastic material containing abrasive particles;
• imparting a relative motion between said workpiece and said displacer member sufficient to cause at least a portion of said abrasive medium to be extruded from one part of said media chamber to another with a positive translational displacement with respect to said displacer member and said workpiece to thereby work said selected workpiece surfaces, said relative motion between the workpiece and displacer being such that the minimum spacing between said displacer member and said workpiece is greater than the maximum dimension of said abrasive particles thereby preventing bridging of any abrasive particles between said displacer member and said workpiece;
• and
• continuing said motion until said selected workpiece surfaces are worked to the extent desired.