Sheet metal fabrication is the process of cutting, bending, forming, and assembling flat sheets of metal into various desired shapes and products.

Here are the answers to the questions:

1. Sheet metal fabrication is the process of cutting, bending, forming, and assembling flat sheets of metal into various desired shapes and products.

2. Four common materials used in sheet metal work are:

   • Mild steel
   • Stainless steel
   • Aluminum
   • Galvanized steel

3. Three properties of a good sheet metal are:

   • Ductility (ability to be drawn into wire or stretched without breaking)
   • Malleability (ability to be hammered or pressed into shape without breaking)
   • Formability (ease with which it can be shaped or bent)

4. The term "gauge" in sheet metal refers to a standardized measurement of the thickness of the sheet metal, where a higher gauge number typically indicates a thinner sheet.

5. Four hand tools used in sheet metal fabrication are:

   • Tin snips
   • Mallet
   • Scriber
   • Steel rule

6. The purpose of a mallet in sheet metal work is to shape, bend, or flatten metal without marring or damaging its surface, often used in conjunction with stakes.

7. Cutting in sheet metal fabrication is the process of separating a sheet of metal into smaller pieces or specific shapes using tools like shears, snips, or plasma cutters.

8. Four types of joints used in sheet metal work are:

   • Lap joint
   • Seam joint (e.g., grooved seam)
   • Hemmed edge joint
   • Corner joint

9. Two safety precautions when working with sheet metal tools are:

   • Always wear safety gloves to protect hands from sharp edges.
   • Always wear safety glasses to protect eyes from flying debris.

10. Marking out in fabrication is the process of transferring the design or dimensions from a drawing onto the workpiece material, indicating where to cut, bend, or drill.

11. The function of a bending machine is to form or shape sheet metal by applying force to create specific angles, curves, or folds.