Study of the effects of minimum quantity lubricants (MQL) on turning steels using uncoated carbide inserts

Abstract

The generation of huge amount of heat in high production machining at high cutting veloeit} and feed rate shortens the tool life and deterioratcs the job quality. 'l1,e conventional cutting tluids arC not that effcctive in such high producti"n machining particularly in continuous cutting of materials like steels, Becausc of these some alternatives has been ',Ought to minimize or even avoid thc use of cutting fluid in machining operation.l. One of these alternativcs is machining with minimum quantity lubrication (MQL). It is a mixture of impinging of least amount of cutting fluid along with highly compres,ed air through a small noalc result, in reducing thc heat produced during metal cutting. The effect, of MQI, on cutting performance, in respect of chip fonnation, chiptool intcrface temperature, cutting forces, tool wear and tool life as well as product quality i.e, dimensional deviation and surface roughncss have bccn studied using t"o different uncoated carbide imerts (SNMM and SNMG) for three different steels viz (i) medium carbon steel (ii) AISI 4140 steel and (iii) A1SI 4320 steel. The same experiments were carried out on thc above under dry condition in order to compare the results \~ith those obtained under MQL conditions. The result indicated that the machining with minimum quantity lubrication (MQL) perf"nned much better than dry or wel machining mainly duc to <ubstantial reduction in culting zone temperature enabling favorable chip-tool interaction. Thi, also facilitated the reduction in cutting forces and substantial reduction in tool wcar in leading to cnhance tool life, dimensional accuracy and surface finish. The overail results of the present investigation clearly rcvealed that proper application of minimum quantity lubricants (MQL) method not only make the machining environment mOre eco-friendly but also provide, substantial technological benefits and hence cconOll1ical gain, which are the reasonable target, of the modern ll1achining industries,