Biomedical Engineering Reference
In-Depth Information
diameter 1.59 mm, cutting diameter 700μm, rotated at a speed of 250,000 rpm
or 26180 rad/s. The rake angle was ʱ=7
0
, clearance angle θ=10
0
and the shear
plane angle θ=24
0
. The material cut was cancellous bovine femur, and the
horizontal force F
h
was calculated using the equation:
F
h
mr
(2)
where m is the tool mass (kg), and r is the tool radius (m). Coefficients of
friction between different materials have been investigated by Bowden and
Tabor [3]. They also describe methods used for the determination of the
coefficient of friction. Using the method of the inclined plane, the coefficient
of friction of cancellous bovine femur on tungsten carbide and steel is in the
range μ= 0.5 - 0.6 under lubricating conditions, i.e. sliding on a plane coated
with a saline solution. Using the following equation,
tan
1
(3)
The friction angle β can then be determined under these conditions. It was
found to be 31
o
under experimental conditions. This is in excellent agreement
with Merchant and Zlatin's nomograph [2] for calculating the coefficient of
friction. The vertical force F
V
can be found using the relationship:
F
F
Tan
h
h
F
(4)
v
1
Tan
This was found to be 5.25N. Again, referring to the Merchant and Zlatin's
[2] nomograph for the coefficient of friction, the value of F
h
can be
independently predicted to be 5.33N. The force perpendicular to the tool plane
F is found to be:
F
F
Sin
F
Cos
(5)
h
v
F was determined as 6.67N. The force normal to the tool plane N is
provided using the equation:
N
F
Cos
F
Sin
(6)
h
v
