Lesson Notes By Weeks and Term v4 - SHS 3
ENGINEERING MATERIALS, TOOLS AND MACHINES
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ENGINEERING MATERIALS, TOOLS AND MACHINES
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
Subject: Applied Technology
Class: SHS 3
Term: 1st Term
Week: 8
Grade code: 3.2.1.LI.2
Strand code: 2
Sub-strand code: 1
Content standard code: 3.2.1.CS.1
Indicator code: 3.2.1.LI.2
Theme: METAL TECHNOLOGY
Subtheme: ENGINEERING MATERIALS, TOOLS AND MACHINES
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This lesson introduces you to the world of modern manufacturing through the Computer Numerical Control (CNC) turning machine, often called a CNC lathe. In Ghana today, from the workshops in Suame Magazine in Kumasi to large-scale industrial plants, automation is changing how we make things. Understanding CNC technology is crucial for any student aiming for a career in modern engineering, manufacturing, or even entrepreneurship. It allows us to create precise, complex, and identical parts much faster than with traditional manual machines. This lesson will equip you with the foundational knowledge to identify the parts of a CNC lathe and understand the basic operations it can perform.
This topic is divided into two main parts: understanding the machine's features and understanding the operations it performs. Part 1: Main Features of a CNC Turning Machine (CNC Lathe)
A CNC turning machine works by rotating a workpiece at high speed while a cutting tool is moved along it to remove material and shape it. Think of it as a highly advanced, computer-controlled version of the traditional centre lathe.
Here are the essential features you must know:
| Feature | Description & Function | Analogy | | :--- | :--- | :--- | | 1. Machine Bed | This is the solid, heavy foundation of the machine. All other components are mounted on it. Its rigidity is crucial for accuracy, as it absorbs vibrations during cutting. | The skeleton of the machine, providing strength and support. | | 2. Headstock | Located on the left side, the headstock houses the main spindle, motor, and gears. The spindle is the part that rotates. The workpiece is held firmly in the spindle by a chuck or collet. | The engine room that provides the power and rotation. The chuck is like the machine's hand that grips the work. | | 3. Tailstock | Located on the right side, opposite the headstock. It is used to support the other end of a long workpiece, preventing it from bending or vibrating during machining. It can also hold tools like drills. | A supporting arm that ensures stability for long objects. | | 4. Carriage / Saddle | This component slides along the machine bed (Z-axis, parallel to the workpiece) and across the bed (X-axis, perpendicular to the workpiece). It carries the tool turret. | The movable platform that carries the cutting tools to the right position. | | 5. Tool Turret | Instead of a single tool post like a manual lathe, a CNC lathe has a turret. This is a rotating block that can hold multiple (e.g., 8, 12, or more) cutting tools at once. The computer can automatically switch between tools as needed for different operations. | A revolving toolbox that quickly changes the cutting tool without stopping. | | 6. Control Panel / CNC Controller | This is the "brain" of the machine. It consists of a screen (monitor), keyboard, and buttons. The operator uses it to input the program (G-code), set up the machine, and monitor the operation. It reads the program and controls all the motors and movements. | The brain and nervous system of the machine, giving all the instructions. | | 7. Ball Screws & Servomotors | These are not visible from the outside but are critical. Instead of manual handwheels, precise servomotors drive the carriage and turret. They turn high-precision ball screws to convert rotary motion into extremely accurate linear motion. This is why CNC machines are so precise. | The muscles and fine-control nerves that execute the brain's commands with high precision. | | 8. Coolant System | A system of pumps and nozzles that spray a liquid (coolant) onto the cutting area. This cools the tool and workpiece, lubricates the cut, and washes away chips (swarf). | The cooling and cleaning system that prevents overheating and keeps the work area clear. |