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Cold Working of Metals |
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Shearing : The operation of cutting blank from continuous sheet to carry further operation.
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Squaring Shears : These are used for producing straight sided blanks of various sizes.
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Alligator Shears : These are used to provide shearing action similar to that of scissors and used to shear
bar stock, rods, plate, etc.
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Rotary Shears : These are used for producing circular or irregular shapes in sheet plate.
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Slitting : The operation which is carried out to divide the parent coiled sheet into narrow coils. Rotary
alligators consists of circular bladed which are used.
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Blanking and Punching : These are the basic die cutting operations. Blanking is carried out to obtain
workpiece blanks of desired shape for carrying further die operations. Punching is done to cut
a slug from stock for producing hole.
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Precision Blanking : The operation which produces high dimensional accuracy of edge of the part along the
entire punched surface. Fine blanking presses require completely ground dies with zero clearance between punch and
die and triple action presses.
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Piercing : In piercing a pointed shaped punch is forced in order to produce a hole with rough flange.
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Perforating : The operation of punching a pattern of holes in similar or continuous rows.
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Notching : The operation of removing excess metal from the edge of a strip to make it suitable for drawing
without wrinkling or to obtain final complicated shape that is not directly possible by blanking.
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Semi-notching : The operation is not used only at edge but throughout the perimeter.
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Lancing : The operation of cutting in a single line across a part of the metal strip to permit bending or
forming in progressive die operation while the part remains attached to the strip.
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Slugging : The operation of punching wherein the punch is stopped as soon as the metal fracture is complete
and thus the slug is not removed but is held in hole.
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Trimming : The operation of cutting off the excess metal at edged which was required for gripping purposes
during press working operation.
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Bending and Flanging : These are the operations which are used to produce shape by stress material beyond
its yield strength but below its ultimate strength.
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Beading : The process of forming shallow, round raised recessed troughs of uniform width in a straight,
curved or circular form.
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Embossing : The operation of creating shallow designs on both sides of metal, so that one side is depressed
and the other is raised.
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Hemming : This operation is used for turning over the edges of sheet in order to provide stiffness and a
smooth edge.
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Bulging : The operation is used to expand a tubular or cylindrical part.
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Cold Roll Forming : The process of forming shapes of uniform cross-section from sheet strip or coiled
stock by means of feeding it longitudinally through successive pairs of rolls, each pair of rolls progressively forming
the stock until the finished cross-section is formed.
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Stretch Forming : The process used to produce contours in sheet metal and of bending previously roll formed
sections.
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Swagging : The process of metal forming in which series of impact blows transferred on dies to the solid
or tubular work cause a change in cross-section or geometric shape.
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Drop Forging : In this operation closed-impression dies are used and there is drastic flow of metal in the
dies due to repeated blows, the impact of that compels the plastic metal to conform to the shape of the dies.
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Hot Bar Forging : The operation of reducing an ingot heated at around 1300o C into bar.
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Upset Forging : In this process a bar of uniform section is gripped in the fixed half of the die so that
the requisite length projects and pressure is applied at the heated end thus, causing it to upset or formed into
some desired shape.
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Cored Forging : The operation is made up of hot-forming parts in dies which include movable cores for
internal shaping.
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Rotary Forging : In this operation four mechanically driven hammers are used to rapidly exert force
simultaneously on four sides of the workpiece. It results in spreading to take place in the desired longitudinal
direction.
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Wobble Forging : In this operation only a small proportion of the part is deformed at any specific time.
The upper die is rotated about an inclined axis which itself is rotating and the lower die is gradually moved up.
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Arc Welding : This operation is performed with carbon or metal electrodes. It can be shielded or unshielded.
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Gas Welding : In this operation heat is supplied by burning a mixture of oxygen and acetylene. The gases are
mixed in a torch or blowpipe that controls the welding flame. Ratio of 1:1 of oxygen and acetylene produces
neutral flame.
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Oxyacetylene Welding : This operation for steel is performed without any flux while fluxes are required for
welding particularly all other metals. Oxygen cutting is used for wrought iron, steel and cast iron.
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Resistance Welding : In this operation coalescence is obtained by the heat which is obtained from the
resistance offered by the flow of electric current in a circuit of which the work is a part and by the application
of pressures.
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Seam Welding : The operation in which the parts are lapped and held in place under pressure.
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Spot Welding : This operation is used to produce a series of spot welds made by circular or wheel type
electrodes.
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Projection Welding : In this operation the heat for welding is derived from the localization of resistance at
predetermined points by projections, embossments, under adequate welding pressure.
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Mash Welding : The seam welding in which the finished weld is only slightly thicker than the sheets and the
lap disappears.
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Butt Welding or Upset Welding : The operation which is used to join members of approximately equal cross-section.
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Flush Welding : In this operation the parts are brought together lightly with current flowing and then
separated slightly. It is a flush which occurs at the interface.
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Percussion Welding : This operation is used to produce heat simultaneously over the entire area of abutting
surfaces from an arc produced by a rapid discharge of stored electric energy followed immediately by the application
of pressure.
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Blazing : The operation which is used to join virtually all metals and dissimilar combinations of metals.
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Turret Lathe : It is designed to produce parts in moderate quantities and to produce interchangeable parts at low
production cost. Turret lathes set up for bar stock are called Screw Machines and used for light work.
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Gear Cutting Machines : The machine or tool which is used to cut teeth in a gear is called Gear Cutting Machine
or Gear Cutter.
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Shapers : These are used for miscellaneous planning, surfacing, notching and production of
flat surfaces.
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Broach : The tool which is provided with many teeth so graded in size that each takes a small chip when
the tool is pulled or pushed by the previously prepared hole.
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Broaching : The production process in which a broach is used to finish internal or external surface for example
holes of circular, square or irregular sections, keyways, teeth of internal gears or flat surfaces etc.
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Polishing : The operation in which coarse scratches or tool marks are removed.
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Buffing : The operation of finish polishing to improve the surface finish.
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Lapping : The process of producing extremely smooth and accurate surfaces by rubbing the surface against a lap.
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Honing : The process which is similar to lapping and which is done by honing stones, usually for finishing bore of
automobile cylinders.
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Single Point Cutting Tool : The standard nomenclature is followed for single point tools and the method of tool
designation.
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Cutting Fluid : It is a fluid which is flowed over the tool and work in metal cutting to reduce heat
generated by friction, lubricate, prevent rust and flush1 away chips. It may be used as flood cooling, mist cooling,
high pressure system or using as solid lubricants.
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