Dynamometer Flashcards
What is the objective of this lab?
Objective of the Lab:
The objective of this lab is to explore the mechanics of metal cutting by measuring and analyzing the forces involved during the cutting process on a lathe. Specifically, the lab aims to:
Understand how cutting parameters (e.g., feed rate, spindle speed, and depth of cut) influence cutting forces and energy consumption.
Use a dynamometer to measure the axial and tangential cutting forces.
Analyze how these forces relate to key cutting parameters, such as power consumption, specific cutting pressure, and cutting speed.
Investigate the effects of vibrations, chip formation, and discoloration on the cutting process.
Apply regression analysis to study the relationships between cutting parameters and measured outcomes.
This knowledge helps to identify the optimal cutting conditions for efficient and effective machining while minimizing tool wear and vibration-related issues.
What is the lab procedures? Part 1
Preparation
Wear safety gear (eye protection, no loose clothing).
Familiarize yourself with the lathe, dynamometer, and controls (feed rate and speed settings).
Ensure the technician mounts the workpiece and dynamometer securely.
Set the tool overhang using a tool-setting gauge and verify its accuracy.
Before Each Cut
Measure the initial workpiece diameter (D₀) using a micrometer.
Adjust the feed rate and spindle speed according to the required settings:
Spindle speeds: 80, 100, 160, 265, 315 rpm
Feed rates: Close to 0.002, 0.003, 0.004, 0.005, and 0.007 in/rev
What is the lab procedures? Part 2
Cutting Process
Operate the lathe to make a cut at the specified speed and feed rate.
Observe the dial gauges and record:
Maximum and minimum deflections for vertical (Ft) and horizontal (Fa) forces.
Measure the final diameter (D₁) of the workpiece after the cut.
Note observations on chip characteristics:
Color: Indicates cutting temperature.
Shape: Breakable chips are preferred over continuous chips.
Repetition
Repeat the process for 25 combinations of spindle speed and feed rate.
Ensure consistent and accurate readings for all cuts.
Post-Experiment
Clean the workspace using a vacuum cleaner and brush for metal chips.
Ensure all deflection readings and observations are logged in the provided table.
What is the conclusion?
This experiment demonstrated the relationship between cutting forces and machining parameters like feed rate, spindle speed, and tool geometry during lathe operations. Using a dynamometer, we observed that higher feed rates increased vertical forces, while horizontal forces were less consistent, likely due to tool deflection and vibrations. Additionally, we analyzed the effects on power consumption and chip formation.
Specific Things to remember
Q: What is the purpose of verifying the dynamometer’s calibration before starting the experiment?
A: To ensure accurate measurements of tangential and axial forces during the lathe operations.
Q: What chip characteristics are important to note during the cutting process?
A: The color, length, and type of chips formed.
