|
Non-metallic deposits on the rake face of high
speed steel (HSS) tools have a considerable effect on tool life. It is
known that for carbide cutting tools used to machine steels, deposited
layers containing aluminium, silicon and calcium are a key factor in
increasing tool life and cutting speeds. However, the existence of
alumina has detrimental effects on tool life.
The conditions required for the formation of these
layers is, however, poorly understood.
In a paper published in AZojomo* by T. L. Banh, Q.
T. Phan and D. B. Nguyen from Thai Nguyen University of Technology,
the authors examine the conditions for the formation of the deposited
layers on the rake face of Physical Vapour Deposited Titanium Nitride
(PVD-TiN) coated HSS cutting tools. These conditions were then
correlated to tool wear.
It is evident from this study that the chemical
composition of the inclusions in the steels does not play an important
role in the formation of the layers. However, the existence of
silicate inclusions in steel, especially their sizes and shapes, has a
direct influence on layer formation. The existence of the silicate
inclusions eliminates a built-up edge (BUE) on the cutting edge and
may be involved with the formation of the white layer in the crater
wear, leading to a reduction in tool wear. |
