Lesson Notes By Weeks and Term v4 - SHS 3
ENGINEERING MATERIALS, TOOLS AND MACHINES
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
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: 10
Grade code: 3.2.1.LI.6
Strand code: 2
Sub-strand code: 1
Content standard code: 3.2.1.CS.1
Indicator code: 3.2.1.LI.6
Theme: METAL TECHNOLOGY
Subtheme: ENGINEERING MATERIALS, TOOLS AND MACHINES
This page supports the lesson note with a companion video and a short classroom-ready summary.
For class groups and homework, share this lesson page so learners also get the summary, objectives, and full lesson context.
This lesson introduces learners to one of the most precise and versatile modern manufacturing tools: the laser. In today's Ghana, from the detailed wooden crafts sold at the Arts Centre to the custom signboards in Osu and the precise metal parts used by fabricators in Tema, laser technology is transforming how we create things. Understanding how lasers work is no longer science fiction; it is a key skill for modern engineers, designers, and entrepreneurs. This lesson will demystify laser technology, explaining how a beam of light can be used to cut, engrave, and shape materials with incredible accuracy, and how to take an idea from a computer screen to a physical product.
2.1 What is a LASER?
A LASER is not just a tool; it's a specific type of light. The name is an acronym: Light Amplification by Stimulated Emission of Radiation
In simple terms, a laser produces a very powerful, highly focused, and single-direction beam of light. Think of the difference between a regular light bulb and a laser: A light bulb spreads light in all directions, like a crowd of people all talking at once. The energy is spread out and weak at any single point. A laser focuses all its energy into a tiny, straight line, like one person shouting through a megaphone. This concentration of energy is what gives it the power to cut or engrave materials. 2.2 How a Laser Cutter Works
A laser cutting machine is a CNC (Computer Numerical Control) machine. This means a computer controls its movement. Here is a simplified breakdown of the process: Laser Generation: Inside the machine, a laser tube (often a CO2 gas laser for non-metals) generates a high-intensity beam of infrared light. Beam Guidance: A series of mirrors, typically three, are positioned to reflect the laser beam and guide it towards the cutting head. Focusing: The cutting head contains a special lens that focuses the wide beam down to a single, tiny, and extremely powerful point (often less than a millimetre wide). Material Interaction: This focused beam is directed onto the material (e.g., wood, acrylic, paper). The intense heat from the beam melts, burns, or vaporizes the material in a very precise line. Computer Control: The computer controls the movement of the cutting head along an X-axis (left-right) and a Y-axis (front-back), following the instructions from a digital design file. This allows it to cut out any shape or engrave any pattern with high accuracy. Assisted Gas/Extraction: Often, a jet of compressed air is used to blow away the vaporized material, resulting in a cleaner cut. A ventilation system is crucial to extract the smoke and fumes produced. 2.3 Common Laser Operations Laser Cutting: This process cuts completely *through* a material. The laser beam moves slowly and with high power to melt or vaporize the entire thickness of the material along a specific path. Ghanaian Context Example: A sign-maker in Accra uses a laser cutter to cut out letters from a 5mm thick acrylic sheet to create a 3D sign for a new boutique. Laser Engraving (or Etching): This process removes only the top layer of a material to create a mark, but does not cut all the way through. The laser beam moves quickly with lower power, vaporizing the surface to create text, logos, or images. Ghanaian Context Example: An event planner in Kumasi orders 100 wooden keychains for a wedding, each engraved with the couple's names and the date. Laser Welding: This is an industrial process where the laser beam is used to melt and fuse two pieces of metal together. It is known for creating very strong, clean, and precise welds with minimal heat distortion. Ghanaian Context Example: A specialized workshop in the Tema Free Zones might use laser welding to join delicate components for medical devices or electronics. 2.4 The Workflow: From CAD Design to Physical Product