Engineering Workshop MECHANICAL THEORY Production Sheet Metal Operations

Sheet Metal Operations:Punching, Blanking, Deep Drawing, Bending, Applications

Sheet Metal Operations: The operations performed on the sheets to get the required shape is called sheet metal operations.

Around 10 Sheet Metal Operations can be performed on the sheet and they are as follows.

Sheet Metal Operations-Punching, Blanking, Deep Drawing, Bending, Applications
Sheet Metal Operations-Punching, Blanking, Deep Drawing, Bending, Applications
  1. Punching 
  2. Blanking
  3. Deep drawing
  4. Bending
  5. Slitting
  6. Perforating
  7. Trimming
  8. Shaving
  9. Nothing
  10. Lancing

The detailed info about (5-10) sheet metal operations are HERE and the rest (1-4) are covered below.

Here, Punching and Blanking Comes under Cutting or Shearing Operations whereas Deep drawing and bending come under Forming Operations.

By physical removal of the material from the sheet, if the required shape of the component is obtained called as cutting or shearing operation.

Sheet Metal Operations-Cutting Operations:

The cutting operations which come under Sheet Metal Operations are

1.Punching Operation

2.Blanking Operation

For both punching and blanking operations, the punch and die combination will be used as tools.

1.Punching Operation:

When the force is applied by using the punch on to the sheet, the cutting or shearing action will be taking place in the sheet producing a piece/blank leaving a hole in the sheet.

Sheet Metal Operations-Punching Operation
Sheet Metal Operations-Punching Operation

In punch and die working, if the hole produced in the sheet is useful, it is called Punching or Piercing operation.

To ensure that the cutting or shearing action is taking place on the sheet, the Punch size is always less than the Die size.

In punching operation, the punch size is made equal to hole size and clearance is provided on the die and also in punching operation, the shear is provided only on the Punch.

 

Note:

  • Punch Size < Die Size(Basic Requirement)
  • Punch Size = Hole Size.(Needed)
  • Clearance → Die.
  • Shear → Punch.

2.Blanking Operation:

When the force is applied by using the punch on to the sheet, the cutting or shearing action will be taking place in the sheet producing a piece/blank.

Sheet Metal Operations-Blanking Operation
Sheet Metal Operations-Blanking Operation

In punch and die working, if the Piece/blank produced in the sheet is useful, it is called as Blanking operation.

In blanking Operation, the die size is made equal to blank size and clearance is provided only on the Punch and also in blanking, the shear is provided only on the die.

Note:

  • Die Size = blank Size.
  • Clearance → Punch.
  • Shear → Die.

 

How Shearing and Tearing is taking place during Cutting Operation?

When the force is applied by using the punch onto the sheet, the elastic compression is taking place on the top side of the sheet and Elastic Elongation will be taking place at the bottom of the sheet.

Due to the Compression and Elongation, the sheet metal present between the punch and die is experiencing Shear stresses.

Due to the continuous application of the load, the shear stresses induced will become greater than or equal to Ultimate Stress of the sheet metal so that shearing and cracking are started taking place at the edges of punch and die and it is propagating in their respective directions and meeting somewhere in the middle cross-section.

hence the piece will get separated from the sheet leaving a hole in the sheet.

From the above, the mechanism by which cutting action taking place is the Shearing and Tearing.

Application of Punching and Blanking Operations:

Punching Applications: Electronic Boards, Printed Circuit Boards etc.

Blanking Operations: Coins etc.

Other Applications:

  • Automobile industries.
  • Kitchen appliances.
  • Aerospace industries.
  • Mass production of sheet metal components.

Sheet Metal Operations-Forming Operations:

The Forming operations which come under Sheet Metal Operations are

3.Deep Drawing Operation:

It is a Sheet Metal forming process in which a sheet metal blank is radially drawn into a forming die by the mechanical action of a punch.

Deep drawing is mainly used for producing Cup-shaped components.

Ex: Most of the utensils used in the kitchen are produced by using Deep Drawing Operation only.

Deep Drawing Operation-Sheet Metal Operations
Deep Drawing Operation-Sheet Metal Operations

In Deep drawing operation, when the force is applied by using the punch, the sheet is simply pulled into the die without any shearing action and taking the shape and size same as that of the die.

But, the edges of the blank will be lifted upwards and produce the foldings or wrinkles on the deep drawing component. This will make the appearance of the component very bad.

To avoid the lifting of the edges of the blank and minimize drawing force, the optimum amount of the Blank Holder Force(BHF) applied is one-third of the Drawing force.

i.e. BHF = P/3.

The BHF can be applied by using spring-loaded stripper plate to maintain it until the punch is completely withdrawn from the component so that the component can be always left over inside the die and it can be removed from the die using ejector pins.

Applications:

 Cookware, Aluminum cans, and kitchen sinks.

4.Bending Operation:

It is used for bending the sheet into the required angle.

  • Straining sheet metal around a straight axis to take a permanent bend is called Bending Process.
  • Metal on the inside of a neutral plane is compressed, while metal on the outside of a neutral plane is stretched.
Bending -Sheet Metal Operations
Bending -Sheet Metal Operations

Types of bending operations:

  1. V bending
  2. U bending
  3. Edge Bending
 V bendingEdge Bending
Performed with a V-shaped diePerformed with a Wiping die
V-Dies are simple and InexpensiveThese dies are complicated and costly.
It is for Low Production.It is for high Production.

Applications of Bending Operation:

  • Drawing board clip, tube light frame, air conditioning duct etc.
  • Automotive industries.
  • Delivery of fluids, either gaseous or liquid, in a process plants in Containers.

This is the explanation of various Sheet Metal Operations that are performed on the sheet to get a required shape which was explained in a detailed manner.

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