Abstract:
I-ligh production machining aLhigil culling speed and iCed rate generates lurge
heat and high culling lemperature. which shortens the tool life and deteriorate, tile job
qllality. Thi" problem becomes more aelile wh~n thcjob; nrc difficllh to macbin~ and arc
to be lIsed under Jynamic loadillg. The conventional culling fluids nrc not that effcctive in
,uch high production machining parlicularly in continuous cultlng of mutcrials Iikc stcels.
Further lhe convcntional culling fluids ure nol ~nvironll1entally friendly. The di,po~al of
lhc culling tluid; oli.cn lead; LOlocal water pollution and soil contaminution. Recycling
and rcu,e of convcntional cutting l1uids also lcad to otbcr problem,. M~cbining of sof\.
,t,cky ~lld dllctil~ l1l~lC";"I,yidd, long conllllUOUScbips and rapid tool wear due 10
inctrLcLcnl action of lh~ CUllingl1ui<l,.In lhe pre,cnl decade, with il1er~asedcnvironmental
awareness, the re,carchcrs are striving to devclop environment fricndly machining
tcchnology; one such t~chnology is to u,c cutling oil wilh high-pressure. The bCl1er,t,of
reduction in macbining tcmperatllfe arc significant rcduction in culling force and Iced
force. The b~nct,ts of high-presslIre coolant are dcpend~nt on tbc proeess paramcter, and
the tool g~ometry.
'I'be rolc of application of high-pressure eool~nt jet on machinabilily of three
dilkrcnt steels (C-60 ;ted, 17CI'NiMo6 slcel and 42CrM04 \!ecl) by two different
uncoated earbide i",crt; (SNMG 120408 and SNMM 120408) have been extensively
,tudied in lenm of mechanics and mechanism or chip formation, c\ming zone temperature,
pattern and extent ofwol wear and it, growth "ith m~ehinlJlg time "long with l11~chihed
sUl'fa~equality in eompOfl.wnto dry and wetlllaehining.
xX
A high-pr~ssur~ coolant jd wns impinged Gil the rake face of the cutting tool
through a "pecL,II)' dcsigned and devcloped noulc. Application of high_pre»ure coolunt
jet showed significant effect on chip formation, culling zone temperature and clLuing
forces. Expectedl)', compared to dry and wet machining, 1001 "ear under high-pres;UI'c
coolant Inachining dccrcascd, c,pccialiy under moderate cutting 8peed-fced comhimtion
through ~Qntrol Qf ClLttingzone lcmpemlUl'c, cutting fOl'ccs, favorable chip-tool intcraction
and retcmioll of cutting edge ,harpncss. S.,M studics of thc worn out ins~rts revcaled that
th~ nOlching and grooVing, Wll;ch are vcry detrimental and may caW,e prcmature and
catastrophic faillLre of the culling tools, are remarkably reduced by high-pressurc coolant
jet. The present high-pre >sure coolant ;ystem increa,ed tool life by 30% to 75% whcn
turning C-60 steel by SNMG in;CI't and 80% to 140% when machining by SNMM insert,
Tile suri'ace qU"lity of the machined ,urfa~e imprQvcd po"ibly duc to 1e1o,crdumage of the
C11(!ingtool no,e.
In ordcr to implemcnt the high-pressure cQo[ant machining technology, an
analyticalmodd for cutting temperature has been developed. It is fmmd that ac~orJing to
the ,elccted cutting condilions in the model-bascd comparisons, the prcdicted cutting
tcmperalllrc under high pressure coolant conditions is rcduccd as higb as about 18%
eomp~red with tho"~ in dJ)' culling.
