Automation in Manufacturing
102605Module 4: Computer Aided Manufacturing
Q1(c). Which G-code gives point-to-point movement?20222m
Module 4: Computer Aided Manufacturing
View this question on its own page →Which G-code gives point-to-point movement?
Worked SolutionAnswer
The G-code for point-to-point (rapid positioning) movement is G00 (G0).
Q1(e). How can the speed and position in CNC be controlled?20222m
Module 4: Computer Aided Manufacturing
View this question on its own page →How can the speed and position in CNC be controlled?
Worked SolutionAnswer
In CNC, speed is controlled mainly by the spindle drive/controller, while position is controlled by the feed-drive/servo system using feedback from position sensors such as encoders or resolvers.
Q3(a). What is PLC? Explain the working of PLC.202214m
Module 4: Computer Aided Manufacturing
View this question on its own page →What is PLC? Explain the working of PLC.
Worked SolutionAnswer
PLC
A Programmable Logic Controller (PLC) is a rugged industrial digital controller used to monitor inputs, execute a stored control program, and operate outputs for controlling machines and manufacturing processes.
Working of PLC
The basic operation is a continuous scan cycle:
- Input scan: The PLC reads the status of sensors, switches and other input devices and stores their states in memory.
- Program execution: The CPU executes the user program, typically written in ladder logic or another IEC 61131-3 language, using the stored input states.
- Output update: Based on the program result, the PLC updates output devices such as motors, solenoid valves, relays and actuators.
- Communication/diagnostics: The PLC performs communication and diagnostic tasks as configured.
- The cycle repeats continuously, allowing the controller to respond to changes in the process.
Block flow: Input devices → Input module → CPU + Program/Memory → Output module → Actuators/process.
Advantages
PLCs are reliable, fast, programmable, easy to modify, suitable for harsh industrial environments, and require less wiring than conventional relay control systems.
Q4(a). Classify CNC machines. Explain which one is suitable for small-scale industries and why.202214m
Module 4: Computer Aided Manufacturing
View this question on its own page →Classify CNC machines. Explain which one is suitable for small-scale industries and why.
Worked SolutionAnswer
Classification of CNC machines
CNC machines may be classified in several ways:
1. According to motion control:
- Point-to-point (PTP): Tool moves between programmed positions; machining is generally performed at the destination.
- Straight-cut: Controlled motion is along one or more coordinate axes to produce straight cuts.
- Contouring/continuous-path: Two or more axes are coordinated simultaneously to machine a continuous profile.
2. According to number of axes: 2-axis, 2.5-axis, 3-axis, 4-axis, 5-axis and higher-axis machines.
3. According to machine tool: CNC lathe/turning centre, CNC milling machine/machining centre, CNC drilling machine, CNC grinding machine, etc.
Suitability for small-scale industries
For small-scale industries, a 2-axis CNC turning centre/CNC lathe is often suitable when the products are mainly rotational components. It provides good accuracy, repeatability and productivity with comparatively lower investment and simpler operation than multi-axis systems. For prismatic components, a 3-axis CNC milling machine is the corresponding economical choice.
Thus, the appropriate CNC machine depends on the type of component and production requirement; for simple turned parts, a 2-axis CNC lathe is generally the economical choice.
Q9(a). Write a CNC program using appropriate G and M code to turn the component shown in the figure. [IMAGE REQUIRED — add the original component/profile figure here.] Raw material: MS 32 \times 50 mm, cutting speed V=40 m/min and feed =0.1. Assume suitable data for depth of cut. The figure specifies the component dimensions and profile.202214m
Module 4: Computer Aided Manufacturing
View this question on its own page →Write a CNC program using appropriate G and M code to turn the component shown in the figure. [IMAGE REQUIRED — add the original component/profile figure here.] Raw material: MS mm, cutting speed m/min and feed . Assume suitable data for depth of cut. The figure specifies the component dimensions and profile.