Introduction to Basic Manufacturing Processes and ... - always yours

348 Introduction to Basic Manufacturing Processes and Workshop Technology
18
CHAPTER
SHEET METAL WORK
18.1 INTRODUCTION
Products made through the sheet metal processing include automobile bodies, utensils,
almirah, cabinet’s appliances, electronic components, electrical parts, aerospace parts,
refrigeration and air conditioning parts etc. Sheet metal is generally considered to be a
plate with thickness less than about 5 mm. Articles made by sheet metal work are less
expensive and lighter in weight. Sheet metal forming work started long back 5000 BC. As
compared to casting and forging, sheet-metal parts offer advantages of lightweight and
versatile shapes. Because of the good strength and formability characteristics, low carbon
steel is the most commonly utilized in sheet-metal processing work. The metal stampings
have now replaced many components, which were earlier made by casting or machining. In
few cases sheet metal products are used for replacing the use of castings or forgings. Sheet
metal work has its own significance in the engineering work. Sheet metal processing has
its own significance as a useful trade in engineering works to meet our day-to-day
requirements. Many products, which fulfill the household needs, decoration work and various
engineering articles, are produced from sheet meta1s. A good product properly developed
may lead to saving of time and money.
In sheet-metal working, there is no need for further machining as required for casting
and forging works. The time taken in sheet-metal working is approximately half of that
required in the machining process. For carrying out sheet metal work, the knowledge of
geometry, mensuration and properties of metal is most essential because nearly all patterns
come from the development of the surfaces of a number of geometrical models such as
cylinder, prism, cone, and pyramid. In sheet metal work, various operations such as shearing,
blanking, piercing, trimming, shaving, notching, forming, bending, stamping, coining,
embossing etc. are to be performed on sheet metal using hand tools and press machines to
make a product of desired shape and size. Generally metals used in sheet metal work are
black iron, galvanized iron, stainless steel, copper, brass, zinc, aluminium, tin plate and
lead.
18.2 METALS USED IN SHEET METAL WORK
The following metals are generally used in sheet metal work:
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