Cutting performance of advanced multilayer coated (TiAlN/AlCrN) in machining of AISI D2 hardened steel
The hard machining of hardened steel with advanced cutting tool has several advantages over conventional method such as short cycle time, process flexibility, compatible surface roughness, higher material removal rate and less environment problems with absence of cutting fluid. However, caused s...
Saved in:
| Main Author: | |
|---|---|
| Format: | Thesis |
| Language: | English English English |
| Published: |
2013
|
| Subjects: | |
| Online Access: | http://eprints.uthm.edu.my/2035/1/24p%20NUR%20AKMAL%20HAKIM%20JASNI.pdf http://eprints.uthm.edu.my/2035/2/NUR%20AKMAL%20HAKIM%20JASNI%20COPYRIGHT%20DECLARATION.pdf http://eprints.uthm.edu.my/2035/3/NUR%20AKMAL%20HAKIM%20JASNI%20WATERMARK.pdf |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | The hard machining of hardened steel with advanced cutting tool has several
advantages over conventional method such as short cycle time, process flexibility,
compatible surface roughness, higher material removal rate and less environment
problems with absence of cutting fluid. However, caused severe tool wear and
changes to quality and performance of product due to higher mechanical stress
and heat generation. Thus, proper criteria should be adopted to keep the longer
tool life and maintaining the quality of surface integrity. In this work, an
experimental investigation was conducted to characterize the machinability of
multilayer TiAlN/AlCrN coated carbide tools and surface integrity in end milling
of AISI D2 hardened steel (58-62 HRC) on a Vertical Machining Centre (VMC).
The cutting variables were cutting speed (80-120 m/min) and radial depth of cut
(3-5 mm), meanwhile feed per tooth (0.05 mm) and depth of cut (0.5 mm) were
kept constant. Tool life and volume of material removed decreased as cutting
speed and radial depth of cut increased due to higher temperature and contact area.
Built-up edge formation, groove formation, and edge chipping were the dominant
tool failure modes; however, the cutting tool was subjected to adhesion and
abrasive wear for the duration of testing. The highest volume of material removed
and tool life were 1500 mm
and 4.97 min which associate to cutting speed of 100
m/min and radial depth of cut of 4 mm. The surface roughness, Ra values attained
throughout the experiments were in range of 0.20 to 0.45 μm which may
acceptable in mould and die fabrication. The optical microscope observations
show that the milled surface is anisotropic in nature. Meanwhile, the surface
defects observed during machining included feed marks, grooves, microchips or
debris and cavities and the existence of surface defects caused by thermal
softening of the material and interaction between cutting tool and workpiece. This
study showed that a thin layer of plastic deformation was formed in the immediate
sub-surface of the workpiece, and the microhardness was altered to a depth of
0.28 mm beneath the machined surface due to high pressure and elevated heat.
Nevertheless, all cutting tools experienced excessive coating delamination by
crack and strip from the substrate due to high friction and thermal cycling
generated and low toughness of the coating. It can be concluded that hard
machining can be carried out for AISI D2 hardened steel with multilayer
TiAlN/AlCrN coated carbide tooling because the process has been proven to
produce high productivity and functional performance of quality machined parts
with respect to surface integrity.
3 |
|---|