Lesson Notes By Weeks and Term v4 - SHS 1
WELDING TECHNOLOGY
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WELDING TECHNOLOGY
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Subject: Applied Technology
Class: SHS 1
Term: 2nd Term
Week: 14
Grade code: 1.4.2.LI.3
Strand code: 4
Sub-strand code: 2
Content standard code: 1.4.2.CS.1
Indicator code: 1.4.2.LI.3
Theme: METAL TECHNOLOGY
Subtheme: WELDING TECHNOLOGY
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Welding is a fundamental skill in metal technology that we see in action all around us every day in Ghana. From the burglar-proof bars on our windows that keep us safe, to the metal gates at our school's entrance, and even the repairs done on a "trotro" by the roadside, welding is the process that joins metal parts together strongly and permanently. Understanding the different types of welding and where they are used is crucial for anyone interested in engineering, construction, or even art. This lesson will focus on the two most common types: Gas Welding and Electric Arc Welding, and we will explore their specific applications in our communities.
This section breaks down the core ideas you need to understand. A. What is Welding?
Welding is a fabrication process that joins materials, usually metals, by using high heat to melt the parts together and allowing them to cool, causing fusion. Think of it like stitching two pieces of cloth together, but instead of thread, you are using molten metal to create a permanent, strong bond. Sometimes, a filler material is added to the joint to form a pool of molten material (the weld pool) that cools to form a joint that can be even stronger than the base material. B. Electric Arc Welding
This is the most common type of welding you will see at roadside workshops in Ghana. How it Works: Electric arc welding uses electricity to create an electric arc (like a tiny, controlled bolt of lightning) between an electrode (the welding rod) and the metal pieces being joined. This arc is incredibly hot (thousands of degrees Celsius), hot enough to melt both the base metal and the tip of the electrode. The molten metals mix together and solidify as they cool, forming a very strong joint. Key Features: Produces very strong welds. Excellent for thicker and heavier metals. Relatively fast process. Can be used outdoors, even in windy conditions. Common Applications in Ghana: Fabrication of Security Fixtures: This is a major application. Burglar-Proof Bars: The metal bars for windows and doors are cut and then welded together using arc welding. Metal Gates and Doors: Strong frames and decorative patterns for compound gates and metal security doors are made this way. Construction: Building Frames: Welding steel beams and columns together to create the skeleton of large buildings. Roofing Trusses: Fabricating the metal framework that supports the roof of a house or warehouse. General Fabrication: Metal Furniture: Making frames for metal chairs, tables, and school desks. Local Containers/Kiosks: Fabricating the metal frames for small shops and containers. Repair of Farm Implements: Mending broken parts of hoes, ploughs, and other heavy farm equipment.
Example: When a welder is making a gate, they cut the hollow metal sections to the right lengths. They then use the arc welder to join the corners. The bright, intense light and sparks you see are from the electric arc melting the metal. C. Gas Welding (Oxy-acetylene Welding)