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

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

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

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

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

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

Steel Rules

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