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Abstract-Minimal quantity lubrication (MQL) is a recenttechnique introduced in machining (in particular, in drilling) to obtain safe, environmental and economic benefits, reducing the use of coolant lubricant fluids in metal cutting. In MQL a very small lubricant flow (ml/h instead of l/min) is used. In this case, the lubricant is directly sprayed on the cutting area. It guarantees a good level of lubrication. The cost of coolant is approximately from 7 to 17% of the total machining cost. This cost continues to rise. So coolant in wet machining operations is a crucial economic issue. An alternative, machining with "minimum quantity lubricant," or MQL, is gaining acceptance as a cost-saving and environmentally friendly option in place of some wet machining processes. In the present work a specially formulated cutting fluid was applied as a high velocity, thin pulsed jet at the immediate cutting zones at an extremely low rate of 2 ml/min using a fluid application system developed for this purpose during turning of hardened steel. The performance of HTMF (Hard Turning -Minimum Fluid) is studied in comparison with that of conventional hard turning in wet and dry form in terms of cutting force, cutting temperature, surface roughness, average flank wear, etc.

An experimental investigation was conducted to study the influence of pitch of helical grooves on condensation heat transfer performance on vertically oriented copper tubes. The condensation heat transfer coefficient of bare as well as grooved copper tubes of various pitches ranging from 2.54 mm to 22.4mm were studied. The investigation revealed that copper tube with groove pitch ≤ 6.35 mm has an adverse effecton the heat transfer performance in comparison to bare copper. The helical groove with pitch > 6.35 mm showed improvement in heat transfer coefficient. The helical groove with pitch 8.47 mm showed a maximum enhancement of 68.4% in condensation heat transfer coefficient at ∆T = 40°C.

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