Metals That Can Be Brazed

Practically all metals and alloys can be brazed or hard soldered satisfactorily with the exception of alloys having zinc, tin, lead or magnesium as base and aluminium alloys containing more than 2% magnesium. Cleaning of Components before Brazing Mechanical cleaning methods are filing, scraping, grinding, polishing and sandblasting. The cleaned parts should not be touched with bare hands. Alloys, on which oxide films grow rapidly, should be brazed soon after cleaning. For chemical cleaning, components should be degreased as suggested below: (a) Steel and Iron. Oxide or scale can be…

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Sheet Metal Thickness Measurement

Many engineering components are produced from a sheet of metal, which is cut to shape and then folded to form the finished article. The edges are then secured by various methods such as welding, brazing, soldering, riveting etc. The term ‘sheet metal’ is normally used to describe metal sheets with a maximum thickness of 2mm. Above this thickness, it is usual to use the term ‘plate’. The sheets of very low thickness (30 to 50 SWG) are known as foils. The thickness of metal sheets is identified by a series…

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Classification of Metal Sheets and Their Uses

Sheet metal work has its own significance in the engineering work. Many products, which fulfill the household needs, decoration work and various engineering articles, are produced from sheet metals. Common examples of sheet metal work are canisters, guards, covers, pipes, hoods, funnels, boxes, etc. Various types of metal sheets are used in aircraft structural work including iron, steel, copper, brass, aluminium, duralumin, etc. Metal sheets are classified on the basis of the material out of which these are made of. For the same metal, sheets are classified according to their…

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Hand Shearing Tools

Many engineering components are produced from a sheet of metal, which is cut to shape and then folded to form the finished articles. The quickest and easy way to cut sheet metal is by shearing it. Cutting tools for sheet metal are also called shearing tools. Shearing tools which are operated by hand are known as hand operated shearing tools. Most commonly used hand operated shearing tools are as follows: Snip (Hand Shear) A snip is used like a pair of scissors to cut thin and soft metals. Light gauge sheet…

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Engineering Engineering Drawing 

Objective, Significance & Utility of Engineering Drawing

A drawing is a graphic representation of a real thing. To draw something as a figure by means of lines expressing some ideas on the paper is known as a drawing. The purpose of the drawing is to define and specify the shape and size of a particular object by means of lines and other information about the object. A good drawing gives full information about the object in the shortest and simplest way. A drawing worked out by an engineer, having engineering ideas, for engineering purpose, is known as…

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Effect of Shear Angle (Shearing Machine)

The shearing action can be explained in the following four stages: (a) Stage 1.   As the top cutting member is moved downwards and brought to bear on the metal with continuing pressure, the top and bottom surfaces of the metal are deformed. (b) Stage 2.     As the pressure increases, the internal fibres of the metal are subject to deformation. This is plastic deformation prior toshearing. (c) Stage 3.     After a certain amount of plastic deformation, the cutting members begin to penetrate. The uncut metal ‘work hardens’ at the edges. (d) Stage 4.     Fractures begin…

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Principles of Shearing Machine

Shearing is a general name for most sheet metal cutting, but in a specific sense, designates a cut in a straight line across a strip, sheet or bar. This procedure leaves a clean edge on the piece of the metal that is sheared or cut. Shearing machines are used to cut or shear metal sheets in many ways. The particular method chosen depends on several factors such as the size and shape of the parts required and the numbers needed.The moving cutting member of a shearing machine may be actuated…

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Shearing Machines & Its Operating Safety Precautions

Guillotine Shears or Machine These are foot operated or power driven. These are used where large sheets are required to be cut with straight edges into strips and rectangular blanks. Sheet width of 600mm x 2mm thick and up to 1200mm x 1.6mm thick can be accommodated on treadle operated guillotine. Guillotines have a moving top blade, which is operated by a foot treadle and a spring, which returns the blade to the top of its stroke. The table is provided with guide to maintain the squareness of work piece….

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Machines Used Sheet Metal Workshop

When a large number of jobs are made, particularly with heavy gauge sheets, hand operations like bending, swaging and rolling are difficult, time consuming and uneconomical. To cope up with this problem, both hand and power operated sheet metal machines are developed. Some of these machines are described in the following paragraphs. Cramp Folding Machine This machine is used for folding or bending thin gauge sheet metal at different angles up to 1350. Bending arms can be adjusted accordingly, when bending sheet metal of different thickness. Slots in the bending…

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Plants Used For Giving Protective Coatings To Metal Components

Many engineering components which are made of sheet metal are given with protective coating to prevent it from corrosion. Protective coating can be in the form of oil, grease, paint, metal spraying, etc. which is to be removed before repair. Some metals form scales of oxide during their storage. For removal of oil, grease, scale etc. various plants and machine are used such as sand blasting plant, degreasing plant. Degreasing plant is used for removing oil and grease from the surface of the job. Sand blasting plant is used for…

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