Lesson Notes By Weeks and Term v3 - Senior Secondary 2
Equipment Set-up (fabrication)
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Equipment Set-up (fabrication)
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Subject: Welding & Fabrication
Class: Senior Secondary 2
Term: 1st Term
Week: 1
Theme: Workshop And Standard Workshop Practices
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identify the parts and accessories of fabrication equipment set-up the equipment for fabrication-• grinding machines• cutting to ols
Workshop And Standard Workshop Practices designed for separating materials. While angle grinders with cutting discs are powerful cutting tools, other manual and mechanical cutting tools are crucial in fabrication. 2.3.1 Hacksaw A manual tool used for cutting metals.
Parts: Frame: The main structure that holds the blade, typically steel.
Blade: A thin strip of high-carbon or high-speed steel with teeth on one edge. Blades come in various tooth per inch (TPI) counts (e.g., 18, 24, 32 TPI) for different materials.
Handle: For gripping, usually plastic or rubberised.
Adjustable Pin/Hook: At the front of the frame, holds one end of the blade.
Tensioning Nut/Wing Nut: Located on the handle end, used to tighten the blade. 2.3.2 Setting Up a Hacksaw
1. Blade Selection: Choose a blade appropriate for the material to be cut. Generally, for thin materials, use a blade with more teeth per inch (finer pitch); for thicker materials, use fewer teeth per inch (coarser pitch). Ensure at least three teeth are in contact with the workpiece at all times.
2. Blade Installation: Ensure the teeth are pointing away from the handle (i.e., forward, in the direction of the cutting stroke). Insert one pin into the hole at the front of the blade and hook it onto the adjustable pin in the frame. Insert the other end of the blade onto the pin near the handle. Tighten the tensioning nut/wing nut until the blade is taut and rigid. A properly tensioned blade will produce a clear pinging sound when plucked. An inadequately tensioned blade will bend and possibly break during use.
3. Safety Check: Ensure the handle is secure and there are no cracks in the frame. 2.3.3 Cold Chisel A hand tool used for cutting, chipping, and trimming cold metals (not heated). While not "set up" in the same way as power tools, its readiness for use is critical.
Parts: Head/Striking End: The blunt end, designed to be struck by a hammer.
Body/Shank: The main length of the chisel, usually hexagonal or octagonal.
Cutting Edge: The sharpened end that performs the cutting action. Different types exist (flat, cross-cut, round nose, diamond point) for various applications. 2.3.4 Readying a Cold Chisel for Use (Setup Considerations)
1. Selection: Choose the appropriate type and size of chisel for the task (e.g., flat chisel for general cutting, cross-cut for grooving).
2. Inspection: Cutting Edge: Ensure the cutting edge is sharp and free from nicks or chips. A dull chisel is inefficient and dangerous, requiring more force and prone to slipping. Sharpen if necessary using a bench grinder with a proper tool rest and coolant.
Head: Inspect the striking end for mushrooming (spreading out due to repeated hammer blows). A mushroomed head can cause metal fragments to fly off, posing a severe eye hazard. Grind off any mushroomed edges carefully.
3. Safety: Always wear safety glasses when using a cold chisel. 2.4 General Safety Practices for Equipment Setup Always read the manufacturer's manual. Wear appropriate PPE (Personal Protective Equipment) such as safety glasses, face shield, gloves, and hearing protection. Ensure equipment is unplugged or de-energized before performing any setup or maintenance. Inspect equipment for damage before each use. Ensure all guards and safety features are in place and correctly adjusted. Keep the work area clean and free from obstructions.
3. Teaching and Learning Activities 3.1 Introduction (10 minutes)
Teacher Activity: Begin by discussing the importance of proper equipment setup in metal fabrication, emphasizing safety, efficiency, and quality of work. Ask students about any experiences they or their family members have had with metalwork tools. Introduce the lesson objectives.
Student Activity: Engage in a brief discussion, sharing experiences and understanding the relevance of the topic. Listen attentively to the objectives. 3.2 Identification of Parts and Accessories (25 minutes)
Teacher Activity: Present actual grinding machines (bench grinder, angle grinder) and cutting tools (hacksaw, cold chisel) if available in the workshop. Alternatively, use large, clear diagrams, posters, or projected images of each piece of equipment. Systematically point to each part and accessory, explaining its name and their family members have had with metalwork tools. Introduce the lesson objectives.
Student Activity: Engage in a brief discussion, sharing experiences and understanding the relevance of the topic. Listen attentively to the objectives. 3.2 Identification of Parts and Accessories (25 minutes)
Teacher Activity: Present actual grinding machines (bench grinder, angle grinder) and cutting tools (hacksaw, cold chisel) if available in the workshop. Alternatively, use large, clear diagrams, posters, or projected images of each piece of equipment. Systematically point to each part and accessory, explaining its name and function. For example, for a bench grinder, show the wheels, guards, tool rests, spark arresters, and eye shields. For an angle grinder, demonstrate the interchangeable discs, guard, and auxiliary handle. For a hacksaw, show the frame, blade, and tensioning mechanism. Encourage students to ask questions and take notes.
Student Activity: Observe the actual equipment or diagrams closely. Actively participate by identifying parts as called out by the teacher. Ask clarifying questions about the function of various parts. Sketch the equipment and label its parts in their notebooks. 3.3 Demonstration of Equipment Setup (35 minutes)
Teacher Activity: Bench Grinder Setup: Demonstrate the step-by-step setup procedure for a bench grinder, emphasizing safety checks (unplugged, PPE) and critical adjustments (tool rest, spark arrester, eye shield distances). Show how to change a wheel if applicable, explaining proper tightening.
Angle Grinder Setup: Demonstrate how to select and correctly mount a grinding or cutting disc onto an angle grinder. Emphasize the use of the spindle lock, proper tightening, and adjustment of the disc guard and auxiliary handle.
Hacksaw Setup: Demonstrate how to correctly insert and tension a hacksaw blade, ensuring the teeth point in the right direction and the blade is taut.
Cold Chisel Readiness: Show a properly sharpened cold chisel and one with a mushroomed head. Explain the importance of a sharp edge and grinding off mushroomed heads for safety. Throughout the demonstration, narrate each step clearly, explaining the "why" behind each action (e.g., "we adjust the tool rest this close to prevent the workpiece from slipping").
Student Activity: Observe the teacher's demonstrations keenly, paying attention to each step and safety precautions. Take detailed notes on the procedures. Ask questions regarding any unclear steps or potential hazards. 3.4 Guided Practice (15 minutes)
Teacher Activity: Divide students into small groups (if equipment allows) or call upon individuals. Guide them through the setup process of each equipment under strict supervision. For instance, have students practice adjusting tool rests on a bench grinder or changing a disc on an angle grinder. Provide immediate feedback and corrections. If equipment is limited, students can practice verbalizing the steps or simulating the actions.
Student Activity: In groups or individually, attempt to perform the setup procedures under the teacher's guidance. Discuss steps within their groups. Verbalise the steps of setting up the equipment. 3.5 Consolidation and Review (5 minutes)
Teacher Activity: Recap the main parts of the equipment covered and the critical steps for their safe setup. Address any lingering questions. Assign homework.
Student Activity: Participate in the recap, ask final questions, and note down homework assignments.
4. Guided Practice (With Solutions)
Question 1: List four essential parts of a bench grinder and briefly state the function of each.
Solution:
1. Grinding Wheel: Performs the abrasive action of grinding, shaping, or sharpening metal.
2. Wheel Guard: Protects the operator from flying sparks, debris, and fragments in case of wheel breakage.
3. Tool Rest: Provides a stable platform for supporting the workpiece during grinding, ensuring control and precision.
4. Eye Shield: A transparent, shatter-resistant shield that offers direct eye and face protection from flying particles and sparks.
Commentary:* This question assesses the students' ability to identify key components and their basic functions, fundamental for understanding equipment operation and safety.
Question 2: Describe the step-by-step procedure for correctly installing a grinding or cutting disc on an angle grinder, assuming the old disc has already been removed.
Solution:
1. Safety First: Ensure the angle grinder is unplugged from the power source. Wear appropriate PPE (safety workpiece during grinding, ensuring control and precision.
4. Eye Shield: A transparent, shatter-resistant shield that offers direct eye and face protection from flying particles and sparks.
Commentary: This question assesses the students' ability to identify key components and their basic functions, fundamental for understanding equipment operation and safety.
Question 2: Describe the step-by-step procedure for correctly installing a grinding or cutting disc on an angle grinder, assuming the old disc has already been removed.
Solution:
1. Safety First: Ensure the angle grinder is unplugged from the power source. Wear appropriate PPE (safety glasses, gloves).
2. Select Disc: Choose the correct type of disc (grinding or cutting) for the task and verify its maximum RPM rating meets or exceeds the grinder's RPM.
3. Position Disc: Place the selected disc onto the grinder's spindle, ensuring it sits flat and flush against the inner flange.
4. Secure with Flange and Nut: Replace the outer flange and then screw on the disc retaining nut.
5. Lock Spindle & Tighten: Press and hold the spindle lock button to immobilize the spindle. Use the provided wrench to firmly tighten the disc retaining nut.
Caution: Do not overtighten, as this can damage the disc or nut.
6. Adjust Guard: Adjust the disc guard to ensure maximum protection, directing sparks and debris away from the operator.
7. Attach Auxiliary Handle: Securely attach the auxiliary handle for safe, two-hand operation.
Commentary: This solution requires students to recall the precise sequence of actions for disc installation, highlighting safety and proper mechanical fastening, which are critical for safe angle grinder operation.
Question 3: Explain how to correctly set up a hacksaw blade for efficient and safe cutting of metal.
Solution:
1. Blade Selection: Choose a hacksaw blade with the appropriate tooth per inch (TPI) count for the material to be cut (e.g., finer teeth for thinner materials, coarser for thicker).
2. Blade Orientation: Insert the blade into the hacksaw frame such that the teeth are pointing forward, away from the handle. This ensures cutting occurs on the forward stroke.
3. Secure Blade Ends: Place one end of the blade onto the fixed pin at the front of the frame. Then, place the other end onto the pin near the handle.
4. Tension the Blade: Use the tensioning nut (or wing nut) near the handle to tighten the blade. Continue tightening until the blade is taut, rigid, and produces a distinct 'ping' sound when flicked.
Caution: An undertensioned blade will buckle and break, while an overtensioned blade can snap.
5. Final Check: Ensure the blade is securely held and properly tensioned before use.
Commentary: This question focuses on a manual cutting tool, testing the understanding of blade orientation and tensioning, which are essential for effective manual metal cutting and preventing blade breakage.
5. Independent Practice (Questions Only)
1. Identify and draw a labelled diagram of a bench grinder, clearly indicating at least six of its main parts.
2. Differentiate between a grinding disc and a cutting disc used with an angle grinder in terms of appearance and primary application.
3. List three critical safety checks that must be performed before starting to set up any power fabrication equipment.
4. Imagine you need to cut a 2mm thick steel sheet using a hacksaw. What TPI (teeth per inch) blade would you likely select, and why?
5. Describe the potential hazards of using a bench grinder with the tool rests adjusted too far from the grinding wheel.
6. You are setting up an angle grinder to remove rust from a metal gate. Which accessory would you choose, and what specific steps would you take to mount it safely?
7. Explain the importance of ensuring a hacksaw blade is properly tensioned during setup. What happens if it's too loose?
8. What is "mushrooming" on a cold chisel, and why is it dangerous? How should it be addressed during preparation for use?
9. A student forgot to adjust the eye shields on a bench grinder. Explain why this is a significant safety oversight.
1
0. Briefly outline the purpose of the spindle lock button on an angle grinder during disc replacement.
6. Evaluation and Assessment 6.1 Formative Assessment: *