SHEET METAL Notes
1. Introduction to Sheet Metal Work
Sheet metal work involves cutting, bending, forming, and assembling thin metal sheets into various shapes. It is widely used in industries such as automobile, HVAC, construction, and appliances.
2. Sheet Metal Tools & Equipment
(A) Cutting Tools
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Hand Shears (Snips) – Used for cutting thin sheets manually.
- Straight snips – For straight cuts.
- Curved snips – For curved cuts.
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Bench Shear – Cuts thicker sheets with lever action.
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Power Shear – Motorized cutting tool for large sheets.
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Nibbling Machine – Used for intricate internal cutouts.
(B) Bending & Forming Tools
- Bar Folder – Used for making sharp bends in sheet metal.
- Slip Roll Machine – Forms cylindrical or curved shapes.
- Press Brake – Hydraulic machine for precision bending.
(C) Joining & Fastening Tools
- Rivet Gun – Used for riveting sheet metal parts.
- Spot Welding Machine – Used for welding thin sheets.
(D) Measuring & Marking Tools
- Steel Rule – Measures dimensions of sheet metal.
- Scriber – Marks lines on the sheet before cutting.
- Combination Square – Checks right angles and measures depth.
- Vernier Caliper – Measures thickness and dimensions accurately.
3. Sheet Metal Equipment & Specifications
| Equipment | Specifications |
|---|---|
| Bench Shear | Cutting capacity: 3-6 mm thick sheets |
| Slip Roll Machine | Roll width: 1000-2000 mm |
| Press Brake | Force: 10-100 Tons |
| Rivet Gun | Rivet size: 3-10 mm diameter |
4. Care & Safety in Sheet Metal Work
✔ Wear gloves to avoid cuts from sharp edges.
✔ Use safety goggles to protect eyes from metal chips.
✔ Handle tools properly to avoid injuries.
✔ Lubricate moving parts of machines for smooth operation.
✔ Store tools properly to prevent rust and damage.
5. Types of Sheet Metal Joints & Their Uses
| Joint Type | Description & Use |
|---|---|
| Lap Joint | Overlapping sheets joined by rivets or welding. Used in roofing. |
| Butt Joint | Sheets placed edge-to-edge, welded or riveted. Used in tanks. |
| Seam Joint | Overlapping edges folded together. Used in ducts and pipes. |
| Grooved Joint | Similar to seam joint but with additional groove for strength. |
| Hemmed Joint | Edges folded over for smooth finish and strength. Used in doors. |
6. Rivets & Riveting
(A) Types of Rivets & Their Uses
- Solid Rivets – Used in aerospace and structural applications.
- Blind Rivets (Pop Rivets) – Used in automobiles and HVAC.
- Tubular Rivets – Used in leather and metal crafts.
- Split Rivets – Used in soft materials like plastic and leather.
(B) Riveting Process
- Drill the rivet hole.
- Insert the rivet.
- Use a rivet gun or hammer to deform the rivet head.
- Ensure a tight joint.
7. Calculation of Blank Sizes from Component Drawing
Blank Size Calculation Formula:
- Bend Allowance depends on material thickness and bend radius.
- Clearance accounts for fitting tolerances.
🔹 Example: For a 100 mm × 50 mm sheet metal box with 10 mm bends:
