Mechanical Technology

Mechanical Technology — July 2015

⎪

Special report

⎪

n May 28, 2015 at its East

London plant, having pro-

duced its one-millionth Mer-

cedes-Benz passenger car, a

white right-hand drive C200 Mercedes-

Benz C-Class, MBSA added a milestone

to its journey as an automotive manu-

facturer of premium brand vehicles. The

millionth vehicle was produced following

a complete overhaul of the manufacturing

plant – a R5-billion investment between

2011 and 2015 mooted to be the

largest single-project investment in the

automotive industry in recent history – to

accommodate mostly export demand for

the new W205 C-Class.

The first Mercedes-Benz passenger

car, a W121 Nap Vista Blue Mercedes-

Benz 190, came off the line of the then

Car Distributors Assembly (CDA) plant

in East London more than 57 years ago.

CDA, the company that would become

Mercedes-Benz South Africa, opened

From the first W121 Mercedes-Benz 190 built at the Mercedes Benz South Africa’s (MBSA’s) East London

plant on January 31, 1958, to the fourth generation W205 C-Class – 2015 World Car of the Year – South

Africa’s premium automotive manufacturer has now produced its millionth car.

MechTech

visits the multi-award

winning manufacturing plant.

ainting of completed car bodies

manufactured in the body shop is a

vital step in ensuring product quality

for the finished vehicle. The quality of the

applied coating is directly responsible for

long-term corrosion protection and vehicle

life. The paint shop is, therefore, a tightly

controlled area that must remain dust free

and under humidity control.

Following manufacture, the built bodies

with mating doors are transported to the

paint shop on conveyors. Each body has

it own transponder with unique informa-

tion about the finished car’s specifications,

including its future colour.

At the paint shop, bodies are transferred

onto skids, which first guide them though

the pre-treatment process.

Pre-treatment:

Each vehicle body is

washed to remove small particles, grit

and obvious debris. Then the whole body

is immersed and degreased in a chemical

Mercedes-Benz South Africa CEO and executive director for manufacturing, Arno van der Merwe, poses

alongside the millionth Mercedes Benz to be manufactured at the company’s East London plant.

MBSA’s new paint shop for the W205

solvent bath before being rinsed with de-

ionised water. They then enter a chemical

dip tank, where the entire body is sub-

merged so that all crevices can receive

chemical treatment.

The whole structure is then electro-coat-

ed. This is an electrolysis-based process,

also called e-coating or electrophoretic lac-

quering, and provides a chemically-bonded

primer layer onto the entire car body. The

electro-coated car bodies then enter a bak-

ing oven to cure the e-primed layer. This

completes the pre-treatment process.

Sealing and masking:

Prior to painting,

areas that will later have adhesives applied

are masked off. The line of bodies is then

conveyed down to the sealant deck, where

all exposed seams have sealant applied to

guard against water ingress and corrosion.

The underside of the body is sealed using

robot applicators, while at critical points,

sealant is applied and spread manually

by operators. The paint line then passes

through a sealer curing oven.

Painting:

Each vehicle receives three coats

of paint, starting with an inspection stage

where any visible defects are removed. The

bodies are moved through an automatic

cleaning station to remove any small dust

particles.

Primer paint is then applied to act as fill-

ing and smoothing agents. The interiors are

manually spray-painted, while all exterior

Mercedes-Benz: from one to one million