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7/31/2019 Auto Tronic s

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AUTOMOBILE ASSEMBLY LINE

By:

Zainab Telya

AUTOTRONICS


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What is an Assembly Line?

An assembly line can be defined as amanufacturing process in which raw materials or

parts are added to a product in a sequential

manner to create a finished product.

An Assembly Line consists of workers and

machines organized into a continuous flow of raw

materials.


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Automobile Assembly Line

Automobile Assembly lines are designed for thesequential organization of workers, tools or

machines, and parts. The motion of workers is

minimized to the extent possible. All parts or

assemblies are handled either by conveyors ormotorized vehicles such as fork lifts, or gravity, with

no manual trucking. Heavy lifting is done by

machines such as overhead cranes or fork lifts.

Each worker typically performs one simpleoperation.


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History of the Car Assembly LineIn 1908, Henry Ford began production of the T-Model automobile. Its creation inaugurated what

we know today as the mass production assembly

line. This revolutionary idea was based on the

concept of simply assembling interchangeable

component parts. Prior to this time, coaches and

buggies had been hand-built in small numbers byspecialized craftspeople who rarely duplicated

any particular unit. Ford's innovative design

reduced the number of parts needed as well as

the number of skilled fitters who had always

formed the bulk of the assembly operation.Ford's first venture into automobile assembly with the Model A involved setting

up assembly stands on which the whole vehicle was built, usually by a single

assembler who fit an entire section of the car together in one place. This person

performed the same activity over and over at his stationary assembly stand. To

provide for more efficiency, Ford had parts delivered as needed to each work

station. In this way each assembly fitter took about 8.5 hours to complete his

assembly task. By the time the Model T was being developed Ford had decided

to use multiple assembly stands with assemblers moving from stand to stand,each performing a specific function. This process reduced the assembly time for


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Principles of an Assembly Line

According to Henry Ford; The principles of assembly are

as follows:

1. Place the tools and the men in the sequence of the

operation so that each component part shall travel theleast possible distance while in the process of finishing.

2. Use work slides or some other form of carrier so that

when a workman completes his operation, he drops the

part always in the same placewhich place must

always be the most convenient place to his handand

if possible have gravity carry the part to the next

workman for his operation.

3. Use sliding assembling lines by which the parts to be

assembled are delivered at convenient distances.


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The manufacturing process of a car

(Assembly Line) consists of thefollowing steps:


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Components

Nowadays, most of the car parts aremanufactured away from the assembly plant and

are transported to the plant by the means of

railroads or by trucks.

These parts are either manufactured by the same

company or are provided by outside suppliers.

More than 4000 parts are all brought together at

the plant for assembly.

Parts used in the chassis are delivered to one

area whereas the parts used in the body are

unloaded at another.


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Chassis Assembly A typical car is constructed from

ground up (and out).

The frames forms the base on which

the body rests and from which all

subsequent assembly components

follow. The frame is placed on the assembly

line and clamped to the conveyer to

prevent shifting as it moves down the

line.

From here the automobile framemoves to component assembly areas

where complete front and rear

suspensions, gas tanks, rear axles

and drive shafts, gear boxes, steering

box components, wheel drums, andbraking systems are sequentially


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An off-line operation at this stage of production mates the vehicle's

engine with its transmission. Workers use robotic arms to install

these heavy components inside the engine compartment of the

frame. After the engine and transmission are installed, a worker

attaches the radiator, and other bolts it into place. Because of thenature of these heavy component parts, articulating robots perform

all of the lift and carry operations while assemblers using

pneumatic wrenches bolt component pieces in place.


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Body Assembly

The body is built up on a separate assembly line from the chassis.

Robots perform most of the welding on the various panels, but

human workers are necessary to bolt the parts together. During

welding, component pieces are held securely in a jig while welding

operations are performed.

First, the left and right quarter panels are robotically disengaged from

pre-staged shipping containers and placed onto the floor pan, where

they are stabilized with positioning fixtures and welded.


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The front and rear door pillars, roof, and body side panels areassembled in the same fashion. The shell of the automobileassembled in this section of the process lends itself to the use of

robots because articulating arms can easily introduce variouscomponent braces and panels to the floor pan and perform a highnumber of weld operations in a time frame and with a degree ofaccuracy no human workers could ever approach. Robots can pickand load 200-pound (90.8 kilograms) roof panels and place themprecisely in the proper weld position with tolerance variations held

to within .001 of an inch. Moreover, robots can also tolerate thesmoke, weld flashes, and gases created during this phase ofproduction.

As the body moves from the isolated weld area of the assemblyline, subsequent body components including fully assembleddoors, deck lids, hood panel, fenders, trunk lid, and bumper

reinforcements are installed. Although robots help workers placethese components onto the body shell, the workers provide theproper fit for most of the bolt-on functional parts usingpneumatically assisted tools.


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Painting

Prior to painting, the body must pass through a

rigorous inspection process, the body in

whiteoperation. The shell of the vehicle passes

through a brightly lit white room where it is fully

wiped down by visual inspectors using cloths

soaked in hi-light oil. Under the lights, this oil

allows inspectors to see any defects in the sheetmetal body panels. Dings, dents, and any other

defects are repaired right on the line by skilled

body repairmen. After the shell has been fully

inspected and repaired, the assembly conveyor

carries it through a cleaning station where it is

immersed and cleaned of all residual oil, dirt, and

contaminants. As the shell exits the cleaning station it goes through a drying booth and then

through an undercoat dipan electro statically charged bath of

undercoat paint (called the E-coat) that covers every nook and cranny of the body

shell, both inside and out, with primer. This coat acts as a substrate surface to

which the top coat of colored paint adheres.


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After the E-coat bath, the shellis again dried in a booth as it

proceeds on to the final paintoperation. In most automobileassembly plants today, vehiclebodies are spray-painted byrobots that have beenprogrammed to apply the exactamounts of paint to just theright areas for just the rightlength of time. Considerableresearch and programminghas gone into the dynamics ofrobotic painting in order toensure the fine "wet" finishes

we have come to expect.

Once the shell has been fully covered 1 Vwith a base coat of color

paint and a clear top coat, the conveyor transfers the bodiesthrough baking ovens where the paint is cured at temperaturesexceeding 275 degrees Fahrenheit (135 degrees Celsius).

After the shell leaves the paint area it is ready for interior assembly.


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Interior Assembly The painted shell proceeds through the interior assembly

area where workers assemble all of the instrumentationand wiring systems, dash panels, interior lights, seats,door and trim panels, headliners, radios, speakers, allglass except the automobile windshield, steering column

and wheel, body weather strips, vinyl tops, brake and gaspedals, carpeting, and front and rear bumper fascias.

Next, robots equipped with suction cups remove thewindshield from a shipping container, apply a bead ofurethane sealer to the perimeter of the glass, and then

place it into the body windshield frame. Robots also pickseats and trim panels and transport them to the vehicle forthe ease and efficiency of the assembly operator. Afterpassing through this section the shell is given a water testto ensure the proper fit of door panels, glass, andweatherstripping.

It is now ready to mate with the chassis.


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Mating The chassis assembly conveyor and the body shell conveyor

meet at this stage of production. As the chassis passes the body

conveyor the shell is robotically lifted from its conveyor fixtures

and placed onto the car frame. Assembly workers, some at

ground level and some in work pits beneath the conveyor, bolt

the car body to the frame. Once the mating takes place theautomobile proceeds down the line to receive final trim

components, battery, tires, anti-freeze, and gasoline.

The vehicle can now be started. From here it is driven to a

checkpoint off the line, where its engine is audited, its lights and

horn checked, its tires balanced, and its charging systemexamined. Any defects discovered at this stage require that the

car be taken to a central repair area, usually located near the

end of the line. A crew of skilled trouble-shooters at this stage

analyze and repair all problems. When the vehicle passes final

audit it is given a price label and driven to a staging lot where it

will await shipment to its destination.


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