How airbags are made

An airbag has to unfold completely in about 20 to 30 milliseconds, which is faster than a blink.

stations: 8
things upstream: 85
raw sources: 25
steps from the ground: 9

The short version

An airbag is a nylon fabric cushion that is sewn, folded and sealed into a module together with a gas inflator. Panels of woven nylon are cut and sewn into a bag. Specialist plants make the inflator. A crash sensor wired to the module signals it to fire, and the bag inflates in a few hundredths of a second.

Weave the nylon cloth

Tough nylon yarn is woven into a tight, strong fabric. A loose weave would leak the gas, and a weak one would tear.

Goes in
Nylon
Seal the fabric with a coating

Some bag designs get a thin coating of silicone to hold in hot gas and protect the fabric.

Goes in
Silicone
Cut the cushion panels

Cutting machines slice stacks of fabric into circles and shaped panels, one pattern for each type of bag.
Stitch the bag

Panels are sewn along their seams with strong thread, often in more than one pass. Some designs have several chambers.

Goes in
Sewing thread
Fold into a tight pack

The finished cushion is folded in a precise pattern so it unfolds in the right direction, and it is compressed into a small cover.
Seal it onto the inflator

Inflators are made in specialist plants under strict controls. Here the folded bag and the sealed inflator are fixed into a metal housing, which will sit behind a trim cover in the wheel or dash.

Goes in
Sheet steel
Link the sensors and controller

The module is wired to a control unit, which reads accelerometers and other sensors. It decides in an instant whether a crash is severe enough to fire the bag.

Goes in
Printed circuit board Microchip
Test modules at random

Samples from each batch are deployed in a test cell, and the bag is checked for speed, shape and leaks.

End of the lineAirbag Next it goes into car, electric car.

Worth repeating

Airbags inflate in approximately 20 to 30 milliseconds, so the bag is full before the forward-moving occupant reaches it.
Research in the 1960s showed that compressed air could not fill a bag fast enough, which led to chemical inflators.