1. 1.0 INTRODUCTION
1.1 Importance of Sheet Metal Work and Bending Machine
What is a metal? It is a strong shinny, which conducts electricity and melts when you make it hot enough. But surely metal must be something more than this because there are other substances such as carbon,, glass and rubbers, which are, obviously not metals but can also variously claim to have strength, elasticity or electrical conductivity.
Furthermore, most of the metals will melt when heated sufficient. What then is a metal? A study of simple metallurgy will show that there is one important factor, which distinguishes metals from non-metals and that is the neat, orderly arrangement of the atoms into regular geometric molecules. Metal is a good conductor of heat and electricity and forming basic oxides.
An alloy is a fused mixture or compound of two or more pure metals. The reasons for making these mixtures are many and various. Pure metals have certain desirable properties but are often lacking in other ways. Therefore it is necessary to mix other metals with them in order to preserve and improve their basic properties. To quote a well known example: Aluminum is a light weight metal which makes it useful for aircraft construction, but it is also soft and weak so a small quantity of copper is added to it to give the necessary strength and rigidity (Courtesy, 1980).
The subsequent development of iron and steel to suit its use in various forms enables it to serve effectively wherever used. Iron and steel remains the most vastly used material for structural works, enclosures and packages.
The most popular forms of iron and steel remains the sheet form, mostly used in enclosure and vessel fabrication. The term metal sheet refers to lighter gauges of steel in rolled form ranging in thickness from approximately 0.4mm to 3.2mm. (Surenda singh, 1979).
Many engineering components are produced from flat sheets of metal which are cut to shape and then folded to form the finished article. The edges are then secured by a variety of methods such as welding, soldering and riveting. The accuracy of the size of drawing the shape on the flat sheet know as the development. Allowance is made at this stage for folding or bending, the amount varying with the radius of the bend and the metal thickness.