Explosive forming is a metal shaping technique that uses an explosive charge to generate high forming pressures. There are two main methods - the stand off method places a metal plate over a die and positions an explosive above the plate, while the contact method places the explosive in direct contact with the workpiece. The rapid conversion of the explosive to gas produces a shock wave with pressures up to several million psi that can form metal sheets into complex shapes in a single operation, making it suitable for aerospace applications requiring large or low-quantity customized parts.

1. EXPLOSIVE
FORMING

2. DEFINITION
“Shaping metal parts in dies by using an explosive
charge to generate forming pressure.”
OR
“The shaping or modifying of metals by means of
explosions.”

3. VARIOUS TECHNIQUES
Explosive Forming Operations can be divided into
two groups, depending on the position of the explosive
charge relative to the work piece.
1. Stand Off Method
2. Contact Method

4. STAND OFF MATHOD
In this method metal plate is placed over a die,
with the intervening space evacuated by a vacuum
pump, then whole assembly is placed underwater and
explosive material is placed at an appropriate height
above the plate. For complicated shapes, a segmented
die can be used.
intervene: become involved

5. CONTACT MATHOD
In this method, the explosive charge is held in direct
contact with the work piece while the detonation is
initiated. The detonation produces interface pressures
on the surface of the metal up to several million psi.

8. PROCESS
The rapid change in explosive in to gas produce a
shock wave. The pressure of this shock wave is sufficient
to form metal sheet.
The peak pressure , p , due to explosion, generated in
water, is given by expression
p = k(((w)^1/2)/R)^a
Where P is in psi. K is the constant depends on the type of
explosive. W is the weight of Explosive in pounds. R is
the distance of explosive from the work piece and a is
the constant.

9. EXAMPLE

10. OTHER EXAMPLES
Rocket engine nozzle Space shuttle skin

11. ADVANTAGES
o It can simulate a variety of other conventional metal
forming techniques such as stamp- or press-forming and
spin-forming in a single operation.
o Explosive hydro-forming can efficiently form large parts
– up to 4’ square or 10’ in diameter.
o It is particularly suitable for short production runs of a
large parts such as occurs in aerospace applications.
o It Maintains precise tolerances and Eliminates costly
welds.

12. DISADVANTAGES
1. Low tooling costs, but high labor cost.
2. Suitable for low-quantity production.
3. Due to shock waves and spillage of water it is not
suitable to carry out indoor.
4. It should be done in open air.

13. COMPARISON
EXPLOSIVE FORMING
• In Explosive forming an
explosive charge is used
instead of a punch or press.
• It can be use for large size of
metal sheets.
• No preheating required
before the explosive forming
• Less production cost.
• Any product size, shape and
sheet thickness is possible.
SUPERPLASTIC FORMING
• In super plastic forming
punch or press is used to
form metal sheet forming.
• It can be only used for
limited die design.
• High production cost.
• It can be used for definite
shape, size and sheet
thickness .