theory of metal cutting assignment problems

1. METAL CUTTING PRACTICE
ASSIGNMENT 1
1. A mild steel rod of Ø 60 mm is machined on a lathe with a single point cutting
tool. Find the motor power using the following data. Cutting Speed = 90 m/min,
Feed = 0.5 mm/rev, Depth of Cut = 2.54 mm, specific power ps= 3.7 kw for
removing one cubic cm per min, Efficiency of motor η = 50%.
2. Estimate the time required for a single cut to bore a 50 long hole from Ø25mm to
Ø30mm with a cutting speed of 18m/min and a feed of 0.25mm/rev.
3. Estimate the power required for the electric motor for a drilling machine to drill a
hole of 15mm dia in mild steel with a feed of 0.2 mm and rotational frequency of
450 rpm. (The specific power for drilling one cm3/min ps =0.037 kw, η=70%).
Compare and contrast the results with the results of the above problem.
4. Calculate the milling cutter offset distance for a 100 mm dia cutter that is to cut a
slot of 25 mm deep. Also determine the time required to mill the slot in a work
piece of 250 mm long with a feed of 12mm/min. Assume 1.5 mm approach and
over travel allowance.
5. Determine the total production time for a batch of 800 components to be milled
two at a time in a fixture on a horizontal milling machine: Length of the
workpiece = 180 mm, Approach = 25 mm, over run = 10mm, Feed/tooth = 0.25
mm, No. of teeth = 10, RPM = 80, Time allowances = for unloading loading and
cleaning 1 ½ mins/cycle and for other allowances = ½ min/cycle.

2. METAL CUTTING PRACTICE
ASSIGNMENT 2
1. What is chip reduction coefficient? Explain in detain with appropriate figures.
2. During a metal cutting test, a frozen chip sample has been obtained while
machining at 200 m/min. The uncut chip thickness (t) is 0.4 mm. The rake angle
(α) is 6°. From the photomicrograph shown in figure calculate the chip reduction
coefficient, shear angle and shear strain.
Ø
ψ
D
E
3. While machining C-20 steel with a P-10 carbide tool at a cutting speed of
200m/min, a chip thickness of 0.38 mm is observed. Under conditions of
orthogonal cutting with a rake angle of +10°, if the feed is 0.2mm/rev, Calculate
shear angle and shear strain.
4. During machining of C-20 steel with a triple carbide tool of 0-10-6-6-8-75-1 mm
ORS configuration shape with a feed of 0.2mm/rev and depth of cut of 2 mm at a
cutting speed of 140 m/min, a chip thickness of 0.36 mm has been obtained.
Calculate the chip reduction coefficient and shear angle.
5. During machining of C-20 steel with a triple carbide tool of 0-10-6-6-8-90-1 mm
ORS configuration shape, the following observations are made: Depth of cut= 2
mm, Feed = 0.2 mm/rev, cutting speed = 200 m/min, FP = 160 kg, FQ= 85 Kg. If
the chip thickness of 0.39 mm has been obtained, calculate
(i) The shear force
(ii) The friction force and normal to the friction force
(iii) The kinetic coefficient of friction
(iv) Shear Energy per unit volume

3. 6. During machining of AISI-304 steel with a carbide cutting tool having a tool
geometry given by 0- (-5)-6-6-8-75-1 mm ORS the following forces have been
recorded by a two dimensional dynamometer.
FZ = 140 kg, and FX = 85 kg.
FX
FZ
FY
Fxy
FX
FZ
FY
R
Calculate the radial component of force FY, the friction force and normal to the
friction force, the kinetic coefficient of friction. (Note: Since cutting angle is not
equal to 90°, FXY must be used instead of FX for calculating Frictional force,
normal to friction force and coefficient of friction.
7. Given feed: 1.198mm/rev, chip thickeness:0.47 mm, tool geometry 0-(-10)-6-6-8-
90-1 mm ORS, cutting speed 200m/min calculate assuming single shear plane, (i)
shear angle, (ii) dynamic cutting strain.