Study of Cutting Technologies for Efficient Processing of Marble Stones

Bong, Hillary Syn (2020) Study of Cutting Technologies for Efficient Processing of Marble Stones. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Marbles are metamorphic rocks widely used in the decorative stone industry as ornamental items for decorations to accentuate living spaces. This is an industrial linked project with Royal Selangor International Sdn. Bhd. Initially, the company spent 12 long hours to cut a marble piece which was completely unacceptable to the company. Hence, a study to identify an automated cutting technology and the process parameters was initiated to reduce the machining time of an oval shaped convex marble. In the process, milling was identified as the most appropriate cutting technology. Diamond end mills namely 6 mm CVD bull nose, 6 mm CVD ball nose, 12 mm PVD standard end mill and 6 mm PVD ball nose were the cutting tools experimented and the corresponding surface roughness and machining time were recorded. The process parameters were optimized with DOE to achieve the specified surface quality requirement of 0.8 μm. From experiment 1, with the help of analysis of DOE with composite desirability of 61.18%, the most optimal stepover of 0.07 mm was validated to produce surface roughness parallel to feed of 1.923 μm and surface roughness perpendicular to feed of 2.039 μm. The total machining time of 96.334 minutes had successfully reduced the initial machining time from problem statement of 12 hours (before post processing) on the Manual Turret Lathe Machine by 86.62%. After post processing of about 1 hour, the final product could be expected to achieve surface roughness of 0.8 μm which fulfilled the requirement of the company. In experiment 2, flare was observed when 12 mm standard end mill was used for roughing at a full design depth of 11.6 mm. Hence, it can be said that for this marble design, 6 mm bull nose end mill was more preferable compared to 12 mm bull nose end mill as the bigger diameter end mill could not offer any reduction in machining time without causing detrimental effects to the workpiece, tool, machine and operator. From experiment 3, it could be said that there was no significant difference between the surface roughness produced by PVD and CVD cutters for finishing stage. All of the research objectives were achieved. As a result, this project managed to reduce total machining time which in turn reduced labour cost while increasing productivity and the company’s revenue and profitability.