Cycle Time AnalysisHypothesis One:5000 pieces/day - 2 shifts/day - 8 Hours a day - 30 min. launch stop - 20 min rest time

Working time/shift= (8 hours X 60min)-(30 min launch time + 20 min rest time)= 430 minDaily working time= (430min X 2 shifts)= 860 min.

AirBag/min= (5000/860 dwt)= 5,81 AB/minCycle Time= (60sec / 5,81 AirBag/min)= 10,32 sec : every 10,32 sec a finished airbag is packed and the production chain shift a position forward the «work in progress» piece. Every production phase must be shorter than 10,32 sec, or right production rate could not be reached.

If 10,32 is a too short cycle time for our machinering we could choose different solutions, for example 3 shift 24/h a day working, or more parallel production chains.

Hypotesis Two, 3 shifts:

Daily working time= (430min X 3 shifts)= 1290 min

AirBag/min= (5000/1290 dwt)= 3,87 AB/min

Cycle Time= (60sec / 3,87 AirBag/min)= 15,503 sec

If a production phase needs double or trice of CT to complete we can use 2 or 3 parallel machine: the subsequential phase in the same time makes 2-3 processing with two small I/O «caches».Clock cycle informatic similitude: CT is similar to a CPU clock cycle.

Economic ConsiderstionsAirbag Component Price/unit(meter)

Canvas 0,40€

Pyrothecnic charge 30€

Canister plastic/metal 10€

Wiring 5€

Connectors 7€

Others 5€

TOTAL 57.4€

Retail price to OEM Charge %

80€ 39,37%

Automation and QualityAirBag are operation crytical components, so quality and reliability are a MUST!

• In small production, the final gain cannot cover the cost of robotized automation, but airbag production is an high production industry, so automation is a good investment.

• Dangerous operations without human risks.

• Robot precision (0.05m) and reliability.

• Reduction in manpower: reduction in costs.

Assembly On CarAirbag installation on car is usually an operation done during interior installation, depending on car type:

• On low class vehicles front passenger airbag is usually installed after the dashboard.

• On high class vehicle usally A.B. must be installed before dashboard due to its coating

Front driver airbags are installed inside the steering wheel center

Lateral, courtain or knee airbags are positioned during the subsequential interior assembly, due to their integration with interior stylish submembers.

Assembly On Car: cont’dDepending on airbag type, assembly of srs subcomponents are quite different, pyrthecnic ones are one-block systems, the operator should only install the package and connect it to wiring.

Hybrid Gas type AB can be different, they could be:

• Integrated, like pyro ones, faster to install, newer solution, less flexible.

• Indipendend systems, with a gas cylinder, one or more valves and pipes to connect one or more inflating envelopes.

Assembly On Car: Connections

Before the interior installation, is usually done the electric system installation, this is comprehensive of the airbag wiring.An Airbag is only as good as its control system: sensors are the «eyes» of the system as the Airbag Control Unit is the brain, it also provide emergency power supply.

ACU is usally installed in a protected position inside passengers compartment, to avoid failures.

Assembly On Car: WiringAB wiring due to its lifesaving objective, couldn’t tollerate malfunctions, so connector use ridondant security locks and sometimes resistive auto-check systems .

Connectors are sealed, gold plated and the use of a special yellow cable (for easy recognition) with a thick insulation and EMF pulse shielding is now common in most production cars.

For steering wheel AB a «clockspring» connector is used to allow steer rotation.

Assembly On Car: SensorsSensors are usually decelerometers:

Firsts sensors where electromechanic and shall’ve been replaced after an accident, like magneto-ball swich or similar roller contact by TRW (roller system without a vacuum tube).

Newer systems use solid-state accelerometers, reusable if not damaged and more reliable.Solid-state accelerometer could be 3D sensors for best precision and relibility.

Sensors Utilization

Quite each airbag type uses his own sensor position:

• Front airbag uses front decelerometer to detect frontal impacts

• Side airbag could inflate also in absence of a frontal impact due to the presence of lateral accelerometer sensors, to protect occupants form lateral collisions

• Courtains airbag should inflate also in case of rollover without other impacts, this is why a rollover sensor is used (also for fuel line interruption)

• In newer cars a weight sensor is positioned under front passenger seat, if he’s not present, front passenger AB will not detonate

Assembly On Car: ElectroTriggersTriggering of air bags depends on their inflation mode:

• Pyrothecnic: a current from the ecu overheat a little resistace that innescate the detonation of the pyro material (detonator system).

• Hybrid Gas-Type: in this case a little pyrothecnic retain capsule valve burns in a small fraction of second allowing the gas to flow inside the bag. (faster than pyrothecnic).

To avoid any oxidation connection problem, as all other SRS system connectors, trigering ones use a «short spring plate» to push contact togheter also in severe oxidation conditions.

Safety on Assembly and TransportAIRBAG TRIGGERING AT WRONG TIME IS LIKE A DETONATION FROM AN HANDGRANADE!So safety during assembly is essential:• Airbag installation must be on correct manufactoring chain point: after the last electric weld• Connection should be checked at least twice, without OHMic testing!• No hi-power EMF are allowed near connections• Battery should not be connected if present, SRS backup power for 90 sec.!

During Transportation:• Airbag must be sealed inside single plastic bag, facing up, with safety space between them

• Must stay away from extreme heat or moist (anti moist salt should be used)

• Must follow explosives normative

During Utilization:Children can use front passenger seat only if FP airbag is not working: security switch.