GB789513A - Improvements in polishing metal articles - Google Patents

Abstract

789,513. Abrasive blasting. ASHWORTH, N. I. July 4,1955 [July 3, 1954], No. 19548/54. Class 60. A process for obtaining a high polish or smooth surface on a hard metal article consists in subjecting the surface to the cutting action of abrasive particles projected thereon in a stream of air or steam and afterwards subjecting the surface to a more delicate cutting action by abrasive particles projected thereon in a stream of liquid to lubricate the surface being cut by the abrasive particles and tocause the cutting action to be concentrated on the protruberances left by the preceding treatment of the surface. The surface may be finally treated by projecting a premixed body of liquid and abrasive on to the surface without the aid of a fluid propellant, e.g., by means of a rotary pump. The surface of an article, e.g., a die or press tool, is first treated by abrasive grit (alumina 60-80 mesh) mixed with water and projected from a spray gun by air or steam under a pressure of 80-120 lbs./sq. in. The surface is then subjected to the action of abrasive grit (80-850 mesh) mixed with water and projected from a spray gun by water at 80-120 lbs./sq. in. The surface is finished by projecting a premixed body of abrasive grit (60-100 mesh) and water from a rotary pump to give a pressure of 40 lbs./sq. in. on the surface. Cutting oil may be used instead of water in all three stages.