Lesson Notes By Weeks and Term v4 - SHS 3
WELDING TECHNOLOGY
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WELDING TECHNOLOGY
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Subject: Applied Technology
Class: SHS 3
Term: 1st Term
Week: 12
Grade code: 3.2.2.LI.3
Strand code: 2
Sub-strand code: 2
Content standard code: 3.2.2.CS.1
Indicator code: 3.2.2.LI.3
Theme: METAL TECHNOLOGY
Subtheme: WELDING TECHNOLOGY
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Welcome, future engineers and technicians! Today, we are exploring two essential techniques for joining metals: soldering and brazing. These methods are not just for large factories; they are used every day in our communities. Imagine the local electronics technician at Circle fixing a phone, a plumber in Madina joining copper water pipes, or an artisan in Kumasi crafting beautiful brass jewellery. They all rely on the principles of soldering and brazing. Understanding how to properly design and create these joints is a valuable skill for repair, creation, and innovation.
A. What are Soldering and Brazing?
Soldering and brazing are two metal-joining processes where a filler metal is melted and drawn into a joint by capillary action. The key difference is that the parent metals (the pieces being joined) are not melted. They are only heated enough to melt the filler metal. Soldering: A low-temperature process. The filler metal, called solder, has a melting point below 450°C. Soldered joints are generally used for applications where high strength is not the primary requirement, such as in electronics and plumbing. Brazing: A high-temperature process. The filler metal, called a brazing alloy or rod, has a melting point above 450°C (but still below the melting point of the parent metals). Brazed joints are much stronger than soldered joints and are used in mechanical and structural applications.
Comparison Table:
| Feature | Soldering | Brazing | | :--- | :--- | :--- | | Temperature | Below 450°C | Above 450°C | | Filler Metal | Solder (usually tin-lead or tin-silver-copper alloys) | Brazing Rod (usually brass, bronze, or silver alloys) | | Joint Strength | Lower | Higher | | Heat Source | Soldering iron, soldering gun, small torch | Oxy-acetylene torch, furnace, induction heating | | Common Uses | Electronics (PCBs), plumbing (copper pipes), sealing cans | Joining steel pipes, bicycle frames, tool tips, jewellery | B. The Science Behind the Joint: Capillary Action