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Surface roughness investigation and hardness by burnishing on titanium alloy

Thamizhmnaii S., Bin Omar B., Saparudin S., Hasan S.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 28, nr 2

139-142

EN

Purpose: Burnishing is a chip less machining process in which a rotating roller or ball is pressed against metal piece. It is a cold working process and involves plastic deformation under cold working conditions by pressing hard. The burnishing process help to improve surface roughness and hardness. Design/methodology/approach: The methodology adopted was using a multi roller on square titanium alloy material by designing various sliding speed/ spindle speed, feed rate and depth of penetration. Findings: The roller burnishing is very useful process to improve upon surface roughness and hardness and can be employed. It will help to impart compressive stress and fatigue life can be improved. The titanium alloy is a difficult to machine material and burnishing is difficult process for this grade material. A low surface roughness and high hardness was obtained for the same spindle rotation, feed rate and depth of penetration. Research limitations/implications: There are some limitations in increasing the operating parameters. It may develop flaw and micro cracks on the surface. Originality/value: The value of the work lies in using the results for other researches to follow and further can be continued on fatigue life.

2

Measurement of surface roughness and flank wear on hard martensitic stainless steel by CBN and PCBN cutting tools

Thamizhmnaii S., Hasan S.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 31, nr 2

415-421

EN

Purpose: The experiments with different operating parameters using CBN and PCBN tools on hard AISI 440 C material were investigated in this paper. Design/methodology/approach: In this research AISI 440 C stainless was used under hard condition. The cutting tools are having three cutting edges and each edge repeated for 5 times. The test conducted by each cutting edge was termed as trail 1, 2, 3, 4 & 5. The length of cutting was 150 mm and each trail. The surface roughness and flank wear, crater wear and BUE were measured by SEM. Findings: The surface roughness was low by CBN at high turning cutting speed and the flank wear was high. The surface roughness was high by PCBN tool than CBN tool and flank wear recorded was low for PCBN tool than CBN tool. The chips produced were saw tooth in all operating parameters. The CBN tool was unable to withstand heat at cutting zone and hence more flank wear occurred. The PCBN tool sustained the temperature and less tool wear occurred. More crater wear formed on PCBN tools where as CBN tool produced less crater wear. The formation of crater wear on the rake face was due to rough surface of the saw tooth chips. Practical implications: The investigation results will provide useful information to applying CBN and PCBN cutting tools in hard turning stainless steels. Originality/value: Hard turning is a latest technology and possible to turn all hard materials. The hard turning produce net shaped products and reduces machining time, low cost per products, etc. The difficult to cut materials like stainless steels was turned by super hard cutting tools like CBN and PCBN to achieve good urface roughness, dimensional control and reduced tool wear.

3

Tool flank wear analyses on martensitic stainless steel by turning

Thamizhmnaii S., Bin Omar B., Saparudin S., Hasan S.

Archives of Materials Science and Engineering

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2008

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Vol. 32, nr 1

41-44

EN

Purpose: Purpose of this research was to demonstrate tool wear by hard turning of martensitic stainless steel and this material is pronounced as difficult to machine material. The evaluation was done using CBN cutting tool on SS 440 C stainless steel with hardness between 45 to 55 HRC. Design/methodology/approach: Turning parameters like cutting speed, feed rate and depth of cut was used. The turning was carried out dry process. Findings: The flank wear was caused by abrasive action between cutting tool and work piece. The heat generated between work piece and tool tip help to form built up edge. The generated heat was conducted easily due to low thermal conductivity of the work piece material. At low cutting speed of 125 m / min with high feed rate of 0.125 mm / rev and 1.00 mm DOC. Research limitations/implications: It was difficult to decide the operating parameters due to physical and chemical properties of the material. Operating at high cutting speed would result in tool flank wear, surface damage and other wears. Originality/value: The originality of this paper lies with conducting experiment and finding optimum operating parameters. The other researches can have as reference.