Foam
Seats for 1100
Before
foam was introduced, seats were made using springs, felt and horse
hair. The main drawback was that although foam came to the factory
as sheets of the right thickness it needed to be cut to shape,
which was rather wasteful. The way forward was to mould the foam in
the required shape.
When British Motor Corporation (BMC) engineers took their ideas to
various producers of foam, their request always produced the same
response 'It can't be done'. So under the direction of Mr.
F.Griffiths, Chief Production Development Engineer for the
Corporation, decided to set up its our own Plastics Department to
look at moulding polyether foam for seats.
There are two basic types of foam. One is called an open cell
construction which acts like a sponge when squeezed and put in
water and released absorbs the water, as all the cells are joined
together. The closed cell construction, where the cells are not
joined together, is the type that is needed in seat construction as
it will support a load.
Making foam is just like cooking; various ingredients are mixed
together and then put in an oven to be cooked. With any production
process, all components made must are made to the same quality.
After much experimenting with different mixes, a recipe that gave
the right support in a seat, and could also be injected into a
mould was arrived at. This would allow seats to be made more easily
and cheaply. The main ingredients used were Polyol, Isocyanate and
water. To prove that the process could be put into production, the
go ahead was given for a pilot plant be installed in the workshop
behind the General Office Block (GOB) on the Lickey Road.
The Longbridge plant had a capacity of 2,000 mouldings per week. At
Cowley an automatic foam plant, based on the pilot plant at
Longbridge, could produce 5,000 seats per week, with two shifts.
The bulk production plant at Cowley had a mixing system made at
Longbridge and a conveyor system made by Fisher & Ludlow
Materials Handling Division, and was in all respects a BMC project.
BMC had the know-how to vary the “give” of the foam mouldings at
will to suit whichever type of application was required. For those
who believed that foam moulding of this quality and production was
a pipe dream. Yet again Longbridge had created a world leading
process.
The
first car to have this method of seat construction was the 1100
range in 1962.
Longbridge
Pilot Plant