07-04-2012, 03:09 PM
Performance of Coated Carbide Tool in Green Turning of FCD 700 Ductile Cast Iron
IMECS2010_pp1602-1605.pdf (Size: 680.79 KB / Downloads: 57)
INTRODUCTION
Metalworking fluids are a double-edged sword. They can be
effective for lubricating and cooling the tool/workpiece
interface and flushing chips, but maintenance, safety, fluid
disposal and air quality can create pricey headaches. As a
result, a growing number of U.S. manufacturers shift to dry or
near-dry machining, seeking benefits ranging from coolant
cost savings to improve tool life to higher value for recycled
chips without having to buy fluid-extraction equipment [1].
Holemaking, however, is an exception.
EXPERIMENTAL WORK
The machining trials were carried out on a Colchester
model Tornado 600 CNC turning machine in dry condition.
The FCD700 (JIS) grade ductile cast iron with spherical
graphite and ferrite was prepared in D100mm x 160mm round
bar. The Brinell hardness and tensile strength are in the range
of 241 HB and 845MPa respectively with elongation of 6%.
Table 1 shows the composition of cast iron grade FCD700
used in the experiment.
RESULT AND DISCUSSION
A. Experimental Results
Table 4 shows the tool life of AC700G grade carbide tools
in minutes when machining ductile cast iron in dry cutting
condition. The longest tool life of 17.63 minutes was
recorded in trial no. 8 at feed rate of 0.3 mm/rev and depth of
cut of 0.6 mm with chilled air coolant application. The longest
tool life was achieved when using chilled air as coolant.
According to the present work [7], when cold wind at low
temperature was supplied during the cutting process, the
degree of high temperature at cutting point could be lowered,
therefore delay the tool wear.
CONCLUSIONS
The application of chilled air was found significantly
improved the tool life as compared with the normal and
without air condition. The tool life was increased by about
30% and 40% when compared with normal air and without air
conditions respectively. The medium of lubrication gave
minimal effect on the surface roughness and cutting force
measured. The wear mechanism was predominantly
controlled by the flank wear on the flank face at all ranges of
cutting speed, and crater wear on the rake face. Wear
mechanisms such as abrasion, micro-attrition and a
‘ridge-and-furrow‘ topography were observed on the flank
wear. The wear was uniformly formed along the cutting edge
due to the low temperature generated as low cutting speed was
used in this experiment.