Sheet-Metal operation

The thickness of metal sheet is identified by a series of numbers blown as standard wire gauge, or SWG. Table 4.1 lists the most frequently used gauges and gives their thickness in millimetres. 

Cutting is carried out using simple snips for thin-gauge steel up to around 20 SWG, treadle-operated guillotines capable of cutting 14 SWG steel, and hand-lever shears for sheet up to 1.5 mm thick. 

Holes and apertures can be cut using a simple hand-operated punch or a punch and die fitted in a fly press. 

For simple bends in thin material, bending can be carried out in a vice. For bends in thicker material with a specific bend radius, folding machines give greater accuracy with less effort. 

Workshop Processes, Practices and Materials. DOI 10.1016/B978 0-08-OB9064 7.00004-1 Copyright O 2010 Bruce J. Black. Published by Bsevier Ltd. All rights of reproduction in any form reserved. 

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To make them realize the importance of the development of lateral surface, students should prepare a 3D model using card sheets. The models prepared by students not only include truncated prisms and pyramids but also the eombination of curved surfaces and flat surfaces as shown in Fig. 2. Demonstration on how to make such models was given in a class so that students learn cost-effectiveness and practical difficulties. This process is more helpful for sheet metal operations, especially for mechanical engineering sciences students. 

Cladding may be less expensive than selective electro deposition when coatings greater than 1 p.m of a noble metal are required, but may be more expensive than electro deposition for thinner coatings. Selective techniques are most easily used for sheet metal substrates that are to be machine stamped and formed into contacts. Clad noble metals are considerably more ductile (and less hard) than comparable electro deposits and, therefore, are better suited to forming operations. Contacts that are made into separate parts from rod by screw machining are usually coated on all exposed surfaces by barrel electroplating. 

Metal enclosed type This type of assembly is completely enclosed on all sides by sheet metal except for the operating handles, knobs, instruments and inspection windows. The more conventional of them in use may be classified as follows,... 

This is in the form of a sheet metal housing, compact in design and elegant in appearance. The feeders are now mounted one above the other up to a permissible height at which the operator can easily operate. It thus makes an optimum utilization of the vertical space and saves on floor area. They can be further classified as follows ... 

Painting. A thorough surface treatment of the sheet-metal and a good painted surface are prerequisites for equipment to provide long years of operation. For the benefit of those in the field of manufacturing of such assemblies, we have provided a brief procedure for the sheet treatment and surface painting of these assemblies in the Appendix. 

Neutral cleaners (non-caustic based) These are ethylene oxide condensates, and easily emulsify the mineral oils and greases. They are more useful for sheet-metal components, which contain no lead compound lubricants (as used for deep-drawing operations), and are also suitable for non-ferrous... 

In practical product design, a full LCA is seldom performed. The unit operations represent whole systems, which are used as building blocks. Typical examples include elementary flows determined for the manufacture of 1 m-1-mm sheet metal of galvanized steel, incineration of 1 kg of polyethylene, or production and distribution of 1 MJ electricity. ... 

In the above case, the laboratory operator had given the designer oral instructions for the hood but did not see the sketch the designer made later for the sheet metal contractor. If the laboratory operator had put his instructions in writing or made a rough sketch, there would have been no misunderstandings. 

Raw materials used by the plant include coil and sheet metal stock, solvent-based marking ink, and protective plastic end caps. The two major operations in this plant, pipe and fitting formation and acid pickling, are described in this section. 

The operation in kneaders or disk mixers begins with the mixing of all the ingredients, except those which sensitize the mixture to impact and friction, e.g. potassium or ammonium perchlorates. Molten TNT or another nitro compound (DNT) is then poured in, the whole is carefully stirred and cooled while stirring. Only when the temperature has fallen to 40-50°C, are the perchlorates added. When the material is cooled down to a temperature of 25-30°C, it is stirred for a certain time, then unloaded and transported in sheet metal or wooden boxes to the storeroom. 

The AN-M2 Destructor, used for the same purpose as the AN-Ml, consisted of a sheet-metal support 5"3/4 x 3 5/8 inches on which two commercial LA-Tetryl electric detonators Ml 1.5 long and 0.25" in diam were mounted and connected in parallel so that they could operate simultaneously upon application of an eleccric current (Ref 2, p 371 Ref 3, pp 4-5 Ref 1, p 206)... 

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