Abstract: Optimization of the metal drilling process requires creation of minimum amount of burrs and uniform appearance of the drilled holes. In this paper, an experimental investigation was performed on sheets of copper using different diameter drills. Cutting data, clamping conditions, and drill geometry were constant and we used different type of entry material like copper, aluminium, backlit and soft wood in order to increase heat transfer rate which produces in drilling process due a to friction of drill with workpiece to be optimize reach the desired quality. The results revealed possible reduction of burr occurrence on both the entry and exit side of the sheet, requiring no additional deburring. The demand on the uniform appearance of drilled holes was fulfilled as well as high productivity achieved. Such optimized process results in a noticeable decrement in job rejection and production cost reduction.

Keywords: Drilling, aluminium, burr minimizing, measurement, vacuum clamping.

Abstract: Enamel is composed of oxide forms, applied on a metal substrate with a firing temperature range of 800-870°C. Vitreous enamel coatings play a very important role in the coating production process of steel in accordance with the technical and aesthetic properties. Surface quality of the enamel coating can be affected by various defects. In this study, most common enamel surface defects obtained during laboratory trials have been investigated and elimination actions have been discussed.

Keywords: Vitreous enamel, Enamel surface defects, Fish scales, Impurities, Burn off, Poor adherence, Blisters.