Air bags are inflatable cushions that protect vehicle occupants during a collision. They are part of an airbag restraint system that supplements seat belts. An airbag system includes airbag modules, crash sensors, an electronic control unit, connecting coils, and wiring. During a crash, sensors detect the impact and signals ignite an inflator that rapidly fills the airbag with gas to cushion occupants within 50 milliseconds. Airbags are manufactured by compressing sodium azide propellant into disks, assembling inflators, sewing nylon fabric into bags, folding bags, and testing completed modules before installation in vehicles.

1. WORKING OF SAFETY AIR BAGS
AND THEIR MANUFACTURING
By
Sandeep Kuriakose
Design and Manufacturing
Department of Mechanical Engineering
National Institute of Technology, Silchar.
Presented on:-08-09-13

2. INTRODUCTION TO AIR BAG
An air bag is an bag is an inflatable cushion
An air inflatable
designed
serious injury in the case
cushion
designed to from to
of a collision. The
protect automobile occupants air bag is part of an
inflatable restraint system, also known as
from serious injury in the case system (ACRS) or
an air cushion restraint
of a collision. an air bag supplemental restraint system
(SRS), because the air bag is designed to
 The air bag is also known as an
supplement the protection offered by seat
belts.
air cushion restraint system
(ACRS) or an air bag
Read
supplemental restraint system
(SRS).
 This is because the air bag is
A car air bag
designed to supplement the
protection offered by seat
belts.

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3. AIR BAG SYSTEM
1.
3.
4.
5.
Air bag module
Crash sensor
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Silchar.
2.
An air bag module
Crash sensors.
A diagnostic monitoring
unit(ECU).
A steering wheel
connecting coil.
Wiring and connectors.
3
Diagnostic monitoring unit
Steering wheel connecting coil

4. AIR BAG SYSTEM WIRING DIAGRAM
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5. HOW AIRBAGS WORK
The crash sensor senses the impact.
2. The diagnosis unit decides.
3. An electric signal is transmitted to the inflator
assembly.
4. The electrical signal then ignites the igniting agent.
5. The gas-generating agent ignites and generates gas.
6. "Airbags" inflate, while the "seatbelt pretensioner"
simultaneously fastens the seat belt and absorbs the
shock received by the passenger.
*Note: actions 1-6 above occur within 50 milliseconds.
1.
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6. AIR BAG DEPLOYMENT
A front air bag deployed
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Before deployment
After deployment
A side air bag deployed
The airbag system ignites a solid propellant (NaN3), which burns extreme
rapidly to create a large volume of Nitrogen gas to inflate the bag. The bag
then literally bursts from its storage site and a second later, the gas quickly
dissipates through tiny holes in the bag, thus deflating the bag.
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7. THE MANUFACTURING OF AIR
BAG
1.
3.
4.
5.
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2.
The propellant
The inflator assembly
The air bag
Final assembly of air bag module
Other components
7
An air bag manufacturing factory

8. RAW MATERIALS
I.
III.
IV.
Nylon thread
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II.
The air bag:-a woven
nylon fabric
Air
bag
coating:silicone and urethane
The inflator canister or
body:-stamped stainless
steel or cast aluminum
The propellant:-Sodium
Azide (NaN3)combined
with an oxidizer.
A woven air bag Nylon fabric
8
Inflator canister
And propellant
Applying silicone and
urethane coating

9. 1.PROPELLANT
The propellant consists of sodium
azide mixed together with an
oxidizer, a substance that helps the
sodium azide to burn when ignited.
 From storage, the sodium azide and
the oxidizer are then carefully
blended
under
sophisticated
computerized process control in
isolated bunkers.
 After
blending, the propellant
mixture is sent to storage. Presses are
then used to compress the propellant
mixture into disk or pellet form.

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10. 2. INFLATOR ASSEMBLY
The inflator components, such as
the metal canister, the filter
assembly(stainless steel wire
mesh with ceramic material
inside)and initiator (or igniter) are
assembled on a highly automated
production line to form inflator
sub assembly .
 The inflator sub-assembly is
combined with the propellant to
form the inflator assembly.
 The inflator assembly is then
tested and sent to storage until
needed.

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A cut section of inflator assembly

11. 3. AIR BAG
The woven nylon air bag
fabric is inspected for any
material defects.
 The air bag fabric is then
die cut to the proper shapes
and sewn, internally and
externally, to properly join
the two sides.
 After the air bag is sewn, it
is inflated and checked for
any seam imperfections.

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Silchar.
A die cut air bag fabric to the shape
11
An inflated air bag for checking

12. 4. FINAL ASSEMBLY OF AIR BAG
MODULE
The air bag is then
mounted to the tested
inflator assembly.
 Next, the air bag is
folded,
and
the
breakaway plastic horn
pad cover is installed.
 Finally, the completed
module
assembly
is
inspected, tested and
packaged.

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Silchar.
Assembly of an air bag module
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13. 5. OTHER COMPONENTS
The remaining components of the air bag system—the crash
sensors, the diagnostic monitoring unit, the steering wheel
connecting coil, and the indicator lamp—are combined with the
air bag module during vehicle assembly.
 All the components are connected and communicate through a
wiring harness.

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Silchar.
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Connecting air bag module to vehicle

14. AIR BAG TESTING
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Silchar.
This is a test rig which is set up in the laboratory.
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15. DEPLOYMENT
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This is a top view of the deployed driver and passenger airbag
(Volvo).
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16. CRASH TESTING
Side air bag crash testing
The airbag systems are crash tested under various
temperatures with and without loadings on the bag.
The results of the test are then fed to the computers where
the results are analysed
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Front air bag crash testing
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17. REFERENCES
Crouse W. H. and Anglin D. L, Automotive Mechanics,
Tata McGraw - Hill Education (2006).
 Kirpal Singh, Automobile Engineering, Standard
Publishers (2011).
 http://www.madehow.com
 http://auto.howstuffworks.com

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18. 18
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QUESTIONS ???

19. 19
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