What is Deep Drawing?
Deep drawing is a metal forming operation in which the sheet metal is stretched into a desired shape by the mechanical action of a punch.
The punch pushes the sheet metal blank downward and forces it into a die cavity which ultimately forms a shape of the desired part.
During the deep drawing operation, the tensile forces cause the sheet metal blank to plastically deform into a cup shaped part.
Generally the term deep drawing is referred to a drawn part which has depth more than its diameter.
The parts drawn by using a deep drawing process can have different cross sections like straight cross section, tapered cross section as well as cylindrical and rectangular parts can be drawn.
For deep drawing operation, the ductile metals like brass, copper, aluminum and mild steel show good drawability even at room temperature.
Deep drawing process in sheet metal
Deep drawing process requires 4 main components.
- Blank holder
A blank is a sheet metal piece which can be in the form of disc or rectangle shape. This blank is cut from a sheet metal which is then kept over the die for its further deep drawing operation.
This sheet metal blank is clamped down over a die with the help of a blank holder.
The punch is then moved down which draws the sheet metal into a shape of a die.
Generally, the power applied to the sheet metal can be produced by using a hydraulic punch.
The die and the punch material should be strong which can resist the pressure formed during the drawing operation.
Hence, the dies and punch are made up of tool steel or carbon steel.
For some deep drawing operations, the complete metal drawing may takes few sequences of steps. This series of steps are called draw reductions.
In each series, the punch gradually stretches the metal deeper than the previous one.
When the desired shape is achieved in the final step, the drawn part is removed from the die.
The extra metal remains as a flange around the drawn metal part (under the blank holder). This can be trimmed off easily.
Now below I have mentioned a few things about deep drawing that you should know.
What is deep draw line?
Some components are complicated to draw. So the drawing process of such metals is done in sequential steps to give the appropriate diameter to the sheet metal.
Such a sequence of deep drawn components is called a deep draw line.
What is the material of dies and punch in deep drawing?
The dies and punch are made up of either tool steel or carbon steel.
If there is a very high resistance and wear of the tool, then cemented carbide is used as a die and punch material.
Which lubricants are used in deep drawing process?
During the deep drawing of sheet metals, there occurs a friction between the die and sheet metal as well as between the sheet metal and the punch.
To minimize this friction, proper lubricant is required so that metal can be drawn easily plus it can be removed easily after being drawn.
Lubricants like heavy duty emulsion, phosphates, wax films, etc are used in deep drawing sheet metal.
Examples of deep drawing
Deep drawing examples are listed below.
#1) Soft drinks cans
You all have seen this and have even used it at least once in your life.
Thus are the soft drink cans which are made by deep drawing process.
#2) Kitchen sink
The metallic sink which is present in your kitchen is made up of sheet metal by metal drawing operation.
#3) Kitchen utensils
The utensils like stainless steel mug, water drinking glass, etc are made by sheet metal deep drawing.
#4) Spray/perfume bottle
The perfume or body spray bottle which you use in your daily life is an example of deep drawing product.
#5) Fuel tank of vehicle
The fuel tanks of vehicles are also made up of sheet metal by deep drawing process.
#6) Metal sleeve
These are metal sleeves being drawn by deep drawing process.
#7) Metal boxes and enclosure
Metal boxes (generally made of aluminum) are manufactured by deep drawing sheet metal.