shearing operation: Blanking, Piercing, Swaging, Lancing, Embossing, Upsetting, Nibbling, Squeezing, Trimming, Shaving, Slitting, Perforating, Notching, Steel Rules

Blanking 


This is the operation carried out on
presses and consists of cutting the outside contour of a stamping. Production
of sheet-metal blanks of flatshapes requires a single -action press equipped
with tools comprising a punch, a corresponding die, a stripper to keep the
sheet from following the punch on its upstroke and means for aligning the sheet
or strip of material and for spacing successive cuts. Cutting inside contours,
i.e. holes and slots is called 
piercing. All
these operations will be dealt in detail under the chapter of presses. However
pressed-metal parts, or stampings are recommended for mass production. Stampings
combine the virtues of lightness, a high degree of uniformity, and surfaces well
adopted to receive protective and decorative finishes.



 In blanking, the piece being
punched out becomes the workpiece and any major burrs or undesirable features
should be left on the remaining strip.

Blanking & Piercing
Blanking & Piercing


Punching & Blanking
 Punching & Blanking




Piercing

This process is
employed for the production of seamless tubes. It offers the most economical
mechanical working, process for the manufacture of seamless tubes. It consists
of passing the hot rolled billet at 11000C. between two conical rollers and
over a mandrel which helps in piercing and controlling the size of bore as the
billet is forced over it.
  In piercing (Punching),
the punch‐out is the scrap and the remaining strip is the workpiece.
 Both done on some form of mechanical press.

Die opening must be larger than punch and known as ‘clearance’.

Punching

Punch = size of hole
Die = punch size +2 clearance
 Remember: In punching punch is correct size.

 Blanking

Die = size of product
Punch = Die size ‐2 clearance
Remember: In blanking die size will be correct


Upsetting 

This is just
opposite to drawing and involves increasing of the cross-sectional area usually
by pressing or hammering in a direction parallel to the original ingot axis. In
the process of upsetting, the shaft or rod is generally gripped in dies, and
the head or flange upset either by a plain flattened ram or with further dies, shaped
to give the desired contour.

Swaging 

Swaging
is used to reduce the diameter of a tube or a rod at the end of the work piece
to create a tapered section. In general, this process is conducted by means of
rotating dies that hammer a workpiece in radial direction inward to taper it as
the piece is fed into the dies. A mandrel is required to control the shape and
size of the internal diameter of tubular parts during swaging. 

Swaging
Swaging

    This operation
consists of applying compressive or impact forces on the metal below the recrystallisation
temperature. It causes the metal to flow in the predetermined shape according
to the design of the dies. Rotary swaging and cold heading are the two
important processes of swaging.



Radial Forging
Radial Forging



Lancing 

A hole is partially cut and then one side is bent down to form a sort of tab or louver. No metal removal, no scrap. It
is a special form of piercing operation in which the entire contour is not cut,
the blanked material remains attached with the sheet. It is achieved by bending
down one side of partially punched hole.

Lancing
Lancing

 Embossing 

 It
is also like a drawing or stretching operation and does not require much
pressure like drawing and coining. It consists of producing, projected or
raised designs in relief on a surface of sheet. It is done with the help of two
mating dies. The sheet is first blanked and then little more force is applied
by the punch which forces the metal against a mating die conforming to the same
configuration as the punch. In this way very little metal is squeezed in the
operation and the words are printed on the sheet in projected form.

Nibbling

a single punch is moved up and down rapidly, each time
cutting off a small amount of material. This allows a simple die to cut complex
slots.

Squeezing

Metal is caused
to flow to all portions of a die cavity under the action of compressive forces.


Trimming

 Cutting unwanted excess material from the periphery
of a previously formed component.

 Shaving

Accurate
dimensions of the part are obtained byremoving a thin strip of metal along the
edges.

Slitting

 moving rollers trace out complex paths during cutting
(like a can opener).

Perforating

Multiple holes which are
very small and close together are cut in flat work material.

Notching

 Metal
pieces are cut from the edge of a sheet, strip or blank.

top 500 GATE guide

Perforating, Ntching & Slitting
Perforating, Ntching & Slitting

Steel Rules

 Soft materials are cut with a steel strip shaped
so that the edge is the pattern to be cut.


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