Design and fabrication of variable speed abrasive grinding and polishing machine for metallographic sample preparation

Abstract

Polishing machine is one of the important equipment for preparing the surfaces of metallic specimens for metallographic examinations. This is to ensure a flat, smooth and mirror-like surface before loading on the metallurgical microscope for viewing and determination of their microstructure. The machine designed and constructed was principled on using locally available materials for its fabrication. The machine components consist of rotating shaft, pulleys, belt, electrical powered motor and the light aluminium alloy polishing disk plate, bush bearing, pillow bearings enclosed in metal case of the fabricated machine. The test-running and assessment of the machine was carried out at different speeds, grits of abrasive papers and on variety of materials (metal alloys, composites, plastic, ceramics) for both dry and wet operating conditions. Also, testing of the machine was carried out with and without specimen on the rotating table for grinding and polishing. The operation of the machine was found to be safe and simple to operate at a reduced minimum maintenance cost. The specimen size should not be less than 25mm in diameter by 10mm thickness for easy hand held polishing operation.