ORIGINAL ARTICLE
An investigation of heat partition and tool wear in hard
turning of H13 tool steel with CBN cutting tools
Mohammad Usman Ghani
&
Nuri A. Abukhshim
&
M. A. Sheikh
Received: 9 January 2006 / Accepted: 9 October 2007 / Published online: 9 January 2008
#
Springer-Verlag London Limited 2007
Abstract This paper presents results of an investigation into
the tool life and the tool wear behaviour of low content CBN
cutting tools used in hard turning of hardened H13 tool steel.
The approach followed here required both experimental
work and finite element thermal modelling. The experiments
involved measuring the cutting forces, cutting temperatures,
tool wear, and the contact area. Using the measured cutting
forces and the contact area in the orthogonal cutting model,
we calculated the heat flux on the tool and applied it in the FE
thermal analysis. The temperatures history from the analysis
was matched with the experimental data to estimate the
fraction of heat entering the tool for both conventional and
high speeds. The heat partition into the tool was estimated to
be around 21–22% for conventional speeds, whereas for
high-speed turning, it was around 14%. The tool wear,
however, was found to be dominated by chipping for both
cutting speeds and could be reduced considerably by
reducing the amount of heat entering the tool.
Keywords High speed machining
.
Hard turning
.
Tool wear
.
Tool life
.
Contact area
.
Heat partition
.
Finite element modelling
Notation
F
λ
Frictional force (N)
F
c
Cutting force (N)
F
s
Feed force (N)
a Rake angle
H
c
Deformed chip thickness (mm)
H Undeformed chip thickness (mm)
λ
h
Chip thickness ratio
V Cutting velocity
V
ch
Chip velocity
P
c
Cutting power
Q Total heat generation
Q
f
Secondary heat generation
Q
f
Heat flux
HSM High speed machining
1 Introduction
Machining is the most important manufacturing process,
forming a substantial part of the world’s manufacturing
infrastructure. It can be applied to a wide variety of work
materials to generate complex shapes with close tolerances
and fine surface finishes [1]. To make it economically
viable, however, it is usually performed after processes like
casting or forming. These processes produce a general
shape of the starting workpiece, which is then machined to
produce the final geometry.
Extensive research into the development of new cutting
tools has enabled the manufacturers to machine very hard
materials. Hard turning is one such process, which is
gradually replacing the traditional machining methods in
the automotive and tool and die industries. The process
produces a fine surface finish and, hence, eliminates the
need for grinding. However, it requires tools of very high
hardness, which need to be continually developed to meet
the ever-increasing demands on machining. This is current-
Int J Adv Manuf Technol (2008) 39:874–888
DOI 10.1007/s00170-007-1282-7
M. U. Ghani
:
N. A. Abukhshim
:
M. A. Sheikh
School of Mechanical, Aerospace and Civil Engineering,
The University of Manchester,
P.O. Box 88, Manchester M60 IQD, UK
Present address:
M. U. Ghani (*)
6 Little Woodbury Drive, Heatherton,
Derby DE23 3UN, UK
e-mail: ghaniusman@yahoo.com