1. Chapter 4: Sheet Metal Forming Shafizan Bt. Shariffuddin School of Manufacturing Engineering UniMAP 1. SHEET METAL AND CHARACTERISTICS

2. INTRODUCTION Some of the major industries in which sheet metal plays an important part are :- –Heating and air-conditioning –Aircraft –Ship building –Freight cars –Refrigeration –Steel furniture, cabinets –Restaurant and cafeteria installation, etc.

3. Definition Sheet metal – generally applies to metals and alloys in sheets rolled to thickness ranging from approximately 0.5 mm – 3 mm.

4. Sheet Metal Process Sheet metal work can be roughly divided into five phases :- 1.Planning and layout Planning and layout are steps by which a flat piece of sheet metal is formed into the finished product. Specifically, through the use of tools and methods, pattern are traced or drawn on the flat sheet of metals in order to serve as a guide for the operations to follow. Drafting, layout and pattern development must be done with care and accuracy.

5. 2. Fabrication The flat sheet metal with the layout on it is fabricated through a number of different operations. Some of the more common operations are :- Cont.  cutting  burning  making seams  grooving  folding  edging  turning  raising  forming  notching patterns  bending  crimping

6. 3. Assembly Individual articles or parts, now shaped and formed, are connected in a number of ways. They must be :- –punched –riveted –drilled –soldered Cont.

7. 4. Installation 5. Repair and Maintenance Installation, repair and maintenance require a good working knowledge of the product, and often involve connecting skills such as drilling, finishing skills. They also require some understanding of basic construction practices. Cont.

8. SHEET MATERIALS A large quantity of sheet metal used is steel rolled into sheets of various thickness and then coated with zinc, tin or lead. Other common metals and alloys which are rolled into sheets are :- –zinc –copper –aluminium –stainless steel

9. Classification of Sheet Metal Sheet metal can be classified into two distinct groups :- –Coated –Solid

10. Coated- particularly steel, has a surface coating of a different metal. The purpose of such coating is to protect the steel from corroding and therefore make it last longer. The coated sheet must never have its surface damaged because in doing so, the coated surface is removed and corrosion resistance is thereby destroyed. Solid – such as copper, stainless steel and aluminium, are made of the same material throughout. Solid sheets can be welded and sanded, filled or given any other process that cuts into the surface, without damaging the corrosion resistance of the sheet.

11. Galvanized Sheet Metal Galvanized sheet metal consists of soft steel sheets coated with zinc. Usually the steel is dipped in the acid bath for cleaning, and then is dipped in a tank of molten zinc to coat the sheet. Sometimes, however, the zinc is put on by an electroplating process. The electroplating process is distinguishable from galvanized coating because it gives an even, grey color and is used principally for its ability to hold a painted surface.

12. SHEET GAGES The thickness of metal sheets is designated by a series of number called gages. Each gage designated a definite thickness. To determine gages of metal, it is important that you know how to read and use micrometer. Number of gageApproximate thickness 103.572 mm 113.175 mm 122.778 mm 132.381 mm 141.984 mm 161.588 mm 220.794 mm 280.397 mm Example: