Study on Tool Life in Turning Carbon Steels

Abstract

The relations between tool life, cutting temperature, mechanical properties of the work materials are experimentally analyzed.
Annealed and normalized plain carbon steels, of which carbon contents are varied from 0.15 % to 0.55 % are turned with carbide tools.
For the aforementioned purpose, only normal or regular type of tool wear is taken into consideration for the tool life criteria.
The major findings are as follows.
(1) Under the fixed condition of work material and tool, the tool life can be defined by one variable function of cutting temperature.
(2) Under the fixed cutting condition of cutting speed, feed per revolution and depth of cut, the tool life is closely related with Brinell hardness H_B, and ultimate strain of the shear test γ_u.
(3) The relationships between tool life equation and mechanical properties of the work materials are as follows.
V·Tⁿ exp (δ·f) d^β=C
n∝H_B^0.23·γ_u^0.22
δ∝H_B^-1.01·γ_u^-0.29
C∝H_B-^1·36·γ_u-^0.145
where, V= cutting speed, m/min,
f=feed per revolution, mm/rev,
d=depth of cut, mm.
Because, it is very difficult to vary said variables independently each other, they are not independent from a physical point of view.
However, the relationships can be derived mathematically, by means of a unique analytical method.