scientific evaluation of cutting-off process in bandsawing

(a) (b)
(c) (d)
Fig. 9 Bandsaw wear modes: (a) flank wear (b) corner wear (c) rake face
wear and (d) blunting or edge radius.
4.3. Wear Mechanisms
In High Speed Steel (HSS) bimetal bandsaw tooth, flank and
corner wear are developed due to the abrasive action between the
tooth and the machined workpiece with small to large amount of
adhesive wear depending the properties of the workpiece materials
[10, 11]. Metal cap or built-up edge is formed at the tooth edge and
this could affect the cutting condition and tooth wear (Fig. 10).
Plastic deformation, micro-chipping and thermal fatigue can also be
observed in some cases.
(a) (b)
Metal cap/
BUE
Rake
face
Rake face
wear
Flank
wear
Clearance
face
Abrasive
wear
Worn flank
Adhered
workpiece
material
Fig. 10 Wear mechanisms in bandsaw teeth when cutting (a) ballbearing
steel and (b) stainless steel.
5. Concluding Remarks
Although bandsawing process has been around for many years,
very little research effort has been devoted to understand the
mechanics of material removal, associated wear modes and
mechanisms and scientific evaluation of the bandsaw products.
Unlike other multipoint cutting tools (e.g., milling) the material
removal process together with the wear and failure modes in
bandsaw is far more complex. Although the method of manufacture
of the cutting edges have been improved from milling to grinding
(giving more uniformity and accuracy of cutting edges), the layer of
material removed is still very small. This causes a complex
combination of chip formation mechanisms (i.e., continuous chip,
ploughing and fragmented chip). Flank and corner wear usually
caused by abrasion and adhesion can alter the edge geometry (e.g.,
edge radius) and affect the chip formation mechanism.
Traditionally the performance of bandsaw is evaluated through
full scale life testing, which is complex and time consuming. Single
tooth time compression technique can be successfully employed to
scientifically evaluate the bandsaw product in a representative way.
Specific cutting energy (Esp) is an excellent parameter for
assessing the tool/workpiece combination efficiency. The high
value of Esp (~10 GJ/m 3 ) indicates that bandsawing is not as
efficient as a single-point turning tool (~1.0-1.5 GJ/m 3 ) where the
chip is free to flow and the layer of metal removed is larger. The Esp
32
also turns out to be a useful parameter to relate various stages of
wear to the bandsaw performance.
6. Reference
[1] Owen, J.V. Bandsaws join the mainstream-Manufacturing
Engineering, 1997, 28-39
[2] Hellbergh, H, M. Persson, M. Sarwar Developments in High
Speed Steel (HSS) cutting edges for band sawing applicationsin:
Proceedings of the HSS forum conference, January 20-21,
2009, Aachen, Germany
[3] Thompson, P.J. Factors influencing the sawing rate of hard
ductile metals during power hacksaw and bandsaw operations-
Metals Technology, 1974, 437-443
[4] Sarwar, M., P.J. Thompson Simulation of the cutting action of
a single hacksaw blade tooth-The Production Engineer, 1974,
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[5] Sarwar, M., P. J. Thompson Cutting action of blunt tools-in:
Proceedings of the International Conference on Machine tool
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[6] Sarwar, M The mechanics of power hacksawing and the cutting
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