Experiment Manual

Experiment Title: Cutting Force Analysis in Turning Operation

Objective: To measure cutting forces in a turning operation and study the effect of cutting speed,
feed, and depth of cut.

Equipments/Tools/Materials used
- Lathe machine
- Single point cutting tool (HSS/Carbide)
- Dynamometer (Lathe tool dynamometer)
- Workpiece (Mild steel bar)
- Tachometer
- Vernier caliper/Micrometer
- Weights and hanger for calibration

Theoretical Aspect of the Experiment

In a turning operation, the cutting tool removes material in the form of chips. The forces involved are
measured using a dynamometer, which records three main components: cutting force (Fc), feed
force (Ff), and radial/thrust force (Fr). These forces vary depending on cutting speed, feed, and
depth of cut. Analysis of these parameters helps in optimizing tool life, surface finish, and machining
efficiency.

Experimental Procedure
1. Mount the workpiece on the lathe and set the cutting tool properly.
2. Connect the tool dynamometer to measure forces.
3. Set initial cutting conditions (speed, feed, depth of cut).
4. Start the lathe and perform the turning operation.
5. Record the dynamometer readings for Fc, Ff, and Fr.
6. Repeat the experiment for different values of speed, feed, and depth of cut.
7. Tabulate the results and plot graphs.

Observations
Cutting Speed (m/min) Feed (mm/rev) Depth of Cut (mm) Fc (N) Ff (N) Fr (N)

Sample Calculation
For example, consider a turning test with cutting speed V = 60 m/min, feed f = 0.2 mm/rev, depth of
cut d = 1 mm. The measured forces are: Fc = 300 N, Ff = 100 N, Fr = 50 N.

Resultant force: Frt = √(Fc² + Ff² + Fr²) = √(300² + 100² + 50²) = 320.2 N.
Cutting power: Pc = (Fc × Vc) / 60 = (300 × 60) / 60 = 300 W.

Discussion
The cutting forces increase with feed and depth of cut, while higher cutting speed usually reduces
forces due to thermal softening of the material. Optimizing these parameters ensures better tool life
and machining economy.

Conclusions
The experiment demonstrates the variation of cutting forces with machining parameters. By
analyzing results, the optimum conditions for machining can be identified.
 Experiment Manual
Experiment Title: To measure cutting forces in a turning operation and study the effect of cutting speed, feed, and
depth of cut.

Name: ____________________
Class & Section: ____________________
Due Date: ____________________

Equipments / Tools / Materials used

- Lathe machine (suitable for turning operations)
- Three-component dynamometer with charge amplifier/indicator
- Single-point cutting tool (HSS/Carbide)
- Workpiece (e.g., Mild steel bar, Ø30–40 mm)
- Vernier caliper / micrometer
- Tachometer
- Cutting fluid (if required)
- Stopwatch
- Dial indicator
- Safety PPE

Theoretical Aspect
During turning, the cutting tool experiences three orthogonal force components:
- Main cutting force (Fc) – tangential component
- Feed force (Ff) – axial component
- Radial force (Fr) – normal component

Effect of parameters:
- Cutting speed: may reduce Fc due to thermal softening
- Feed: increases forces due to larger chip load
- Depth of cut: increases forces approximately linearly

Experimental Procedure
1. Mount workpiece and dynamometer.
2. Calibrate and record zero readings.
3. Set tool geometry at center height.
4. Select cutting parameters (V, f, ap).
5. Perform turning cut and record force readings.
6. Convert readings using calibration.
7. Repeat for various speeds, feeds, and depths.

Observation Table (example)

Run V (m/min) f (mm/rev) ap (mm) Vout_c (mV) Vout_f (mV) Vout_r (mV) Fc (N) Ff (N) Fr (N)
1 100 0.15 1.0 20 5 8 80 20 32

Sample Calculation
Calibration factor = 4 N/mV
Fc = 20 mV × 4 = 80 N
Ff = 5 mV × 4 = 20 N
Fr = 8 mV × 4 = 32 N

Cutting speed V = 100 m/min = 1.667 m/s

Power P = Fc × V = 80 × 1.667 = 133.3 W

Material Removal Rate Q = V × f × ap = 1.667 × 0.00015 × 0.001 = 2.5 × 10■■ m³/s

Specific Energy U = P / Q = 133.3 / (2.5×10■■) = 5.33×10■ J/m³ = 0.533 J/mm³

Discussion
Forces increased linearly with feed and depth of cut. Cutting speed showed slight decrease in Fc due to thermal
softening. Fc > Fr > Ff in magnitude.

Conclusion
Cutting forces depend strongly on feed and depth of cut, while speed has a secondary effect. The experiment validates
theoretical trends.
 Cutting Force Analysis in Turning Operation
Objective: To measure cutting forces in a turning operation and study the effect of cutting speed,
feed, and depth of cut.

Equipment Used:
• Lathe machine
• 3-component dynamometer
• Single point cutting tool
• Workpiece (mild steel)
• Measuring instruments (caliper, tachometer)
• Computer with data system
• Safety equipment

Theory:
In turning, three forces act on the tool: Cutting force (Fc), Feed force (Ft), and Radial force (Fr).
Cutting force mainly controls power. Feed and depth of cut increase the forces, while higher speed
reduces them slightly. Useful formulas: - Cutting speed: V = πDN / 1000 - Material removal rate
(MRR): π D f d N - Power: P = Fc × V / 60 - Specific energy: u ≈ Fc / (f d)

Procedure:
1. Fix workpiece and tool in lathe.
2. Connect tool with dynamometer.
3. Set speed, feed, and depth of cut.
4. Run machine and record forces.
5. Repeat by changing one parameter at a time.
6. Record readings and calculate values.

Observation Table:
Trial D (mm) N (rpm) f (mm/rev) d (mm) V (m/min) Fc (N) Ft (N) Fr (N)
T1
T2
T3

Conclusion: Cutting force increases with feed and depth, and decreases slightly with speed.
Power and energy can be estimated from measured values.

Viva Questions:
1. What are Fc, Ft, and Fr?
2. Write formula for cutting speed.
3. Why does cutting force reduce with higher speed?
4. What is specific cutting energy?
 Cutting Force Analysis in Turning Operation
Experiment Manual

Name, Class & Section: ______________________________

Experiment Title: Cutting Force Analysis in Turning Operation
Due Date: ______________________________

Objective(s): 1) To measure the main cutting force and associated feed and radial forces in a lathe turning
operation using a 3■component dynamometer. 2) To study the effect of cutting speed, feed and depth of cut on
cutting forces. 3) To estimate power requirement and specific cutting energy.
Equipments/Tools/Materials used
• Centre lathe with variable speed drive

• 3■component lathe tool dynamometer (Fx, Fy, Fz) with charge amplifier/data acquisition

• Single■point cutting tool (HSS or carbide) with known tool geometry

• Workpiece material (e.g., mild steel bar, Ø 25–60 mm)

• Tachometer or spindle RPM display

• Vernier caliper/micrometer (to measure initial & final diameters)

• Feed/depth controls on lathe; cross■slide & compound rest

• Computer with acquisition software/indicator

• Safety PPE: safety glasses, apron, shoes, chip brush & coolant (if used)

Theoretical aspect of the experiment

In orthogonal turning, the cutting force system can be resolved into three mutually perpendicular components
measured by a lathe tool dynamometer: Fc (tangential or main cutting force), Ft (feed/thrust force) and Fr (radial
force). The tangential component dominates power consumption and tool loading. For a given tool-work
combination, forces increase with feed (f) and depth of cut (d) approximately linearly, and decrease mildly with
cutting speed (V) due to thermal softening and reduced built-up edge.

Useful relations: Cutting speed, V (m/min) = π D N / 1000, where D is current work diameter (mm) and N is spindle
speed (rev/min). Material removal rate, MRR (mm3/min) = π D f d N. Cutting power, P (W) = Fc × V / 60 (when V is
in m/min). Specific cutting energy, u (J/mm3) = P / (MRR/60) = Fc / (f d) (approx. using chip cross■section b×t ≈ f×d
in turning). Assumptions: steady-state turning, negligible tool wear during short cuts, dry cutting unless coolant is
specified.

Experimental procedure
1 Mount the workpiece in chuck; face and center■drill if necessary to ensure concentricity.
2 Set tool geometry and tool height at lathe centre. Connect the tool to the 3■component dynamometer and zero
the channels.

3 Select initial cutting conditions (e.g., D≈50 mm; choose N, f, d). Record D, f, d and compute V using V =
πDN/1000.

4 Start the spindle; take a trial pass to stabilize cutting. Begin data logging; perform a straight turning pass
(~50–80 mm).

5 For each pass, record steady■state plateaus of F_c, F_t, F_r (average values).
6 Repeat for at least 3 combinations varying one parameter at a time (speed test: vary N; feed test: vary f; depth
test: vary d).

7 Measure final diameter to confirm depth of cut. Ensure only one variable is changed per set; others kept
constant.

8 Stop the machine. Save/label datasets clearly (e.g., S1, S2 …). Clean chips and switch off power.

Observations
 Trial D (mm) N (rev/min) f (mm/rev) d (mm) V (m/min) F_c (N) F_t (N) F_r (N)
T1
T2
T3
T4
T5

Sample calculation (worked example)

Given: D = 50 mm, N = 500 rpm, f = 0.20 mm/rev, d = 1.00 mm; measured F_c = 600 N, F_t = 250 N, F_r = 150 N.
Cutting speed, V = πDN/1000 = 78.54 m/min.
MRR = π D f d N = 15,708 mm³/min.
Power, P = F_c × V / 60 = 785.4 W.
Specific cutting energy, u ≈ F_c / (f d) = 3000.0 J/mm³.

Experimental and/or calculated results

1) Present a results table for each study (speed, feed, depth) showing D, N, f, d, V and the averaged forces (F_c,
F_t, F_r). Also compute P and u for each trial. 2) Plot graphs: (a) F_c vs f at constant d and V; (b) F_c vs d at
constant f and V; (c) F_c vs V at constant f and d; (d) P vs MRR. 3) Comment on the trends and compare with
theoretical expectations (near■linear dependence on f and d; slight decrease with V).
Trial V (m/min) F_c (N) F_t (N) F_r (N) P (W) MRR (mm³/min) u (J/mm³)
T1
T2
T3
T4
T5

Discussion
• Discuss how F_c varies with f and d. Do slopes match textbook linear behaviour?

• Explain any reduction of F_c with higher V (thermal softening/BUE reduction).

• Comment on the magnitude of F_t and F_r relative to F_c and what it implies for tool deflection & surface finish.

• Identify sources of error: dynamometer calibration, transient readings, chatter, incorrect d due to spring back,
worn tool, temperature rise etc.

• Compare specific cutting energy u across trials; relate to material machinability.

Conclusions
Summarize: (i) measured force components; (ii) the effect of feed, depth and speed on forces; (iii) estimated cutting
power and specific energy; (iv) any practical recommendations for selecting cutting parameters.

All calculations and graphical work (e.g., graphs) must be hand written/drawn in your record as per instruction.
Viva■voce (expected questions)
1 Define F_c, F_t, F_r. Which component governs power?
2 Write formulas for V and MRR in turning.
3 Why does F_c reduce with increasing speed?
4 How does tool nose radius or rake angle affect forces?
5 What is specific cutting energy and how is it estimated?
6 List typical errors when using a lathe tool dynamometer.

Safety precautions
• Wear eye protection; keep hands clear of the rotating chuck; avoid loose clothing.

• Use chip guard and brush—never remove chips by hand.

• Ensure tool is clamped rigidly and tool height is set at centre.

• Do not exceed recommended spindle speeds; stop the machine before measuring.

• Clean the area after completion and switch off main power.
Experiment Manual
Experiment Title: Cutting Force Analysis in Turning Operation

Name: _______________________
Class & Section: _______________________
Due Date: _______________________
Equipments / Tools / Materials Used
• Centre lathe with variable speed drive
• Lathe tool dynamometer (3-component)
• HSS/Carbide single-point turning tool
• Cylindrical workpiece (material noted)
• Chuck, tailstock, tool post
• Vernier caliper / outside micrometer
• Tachometer (optional)
• Cutting fluid / coolant
• Safety goggles, apron, chip guard
Theoretical Aspect of the Experiment
In turning, the cutting force system acting on the tool can be resolved into three orthogonal
components: - Main cutting force (Fc): Tangential direction, dominant in power. - Feed force (Ff):
Axial direction along tool feed/work axis. - Radial (thrust) force (Fr): Radially outward, pushing tool
away. Formulas: - Cutting speed: V = (πDN)/1000 (m/min) - Chip area: A = f × d (mm²) - MRR:
(1000V) × f × d (mm³/min) - Power: P = Fc × v (W), where v = V/60 in m/s - Specific energy: u =
Fc/(f·d) (N/mm²)
Experimental Procedure
• Mount workpiece and set up cutting tool at center height.
• Install dynamometer and zero calibration.
• Vary feed, depth of cut, or speed one at a time while recording Fc, Ff, Fr.
• Compute cutting speed, MRR, power, resultant force, specific energy.
• Repeat trials and record observations in tables.
• Ensure safety precautions during operation.
Observations
Prepare tables like below:
Trial D (mm) N (rpm) V (m/min) f (mm/rev) d (mm) Fc (N) Ff (N) Fr (N)
1
2
3
Experimental and/or Calculated Results
Sample Calculation:
Given: D=30 mm, N=600 rpm, f=0.20 mm/rev, d=1.0 mm, Fc=380 N, Ff=110 N, Fr=150 N - V =
56.55 m/min → v = 0.9425 m/s - MRR = 11,310 mm³/min - P = 358.2 W - R = 424 N - u = 1900
N/mm²
Discussion
Analyze how cutting, feed, and radial forces vary with parameters. Compare specific energy trends
with MRR.

Conclusions
Summarize observed cutting force ranges, dominant components, and estimated power
requirements.