FT911-139
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FT 14 MAY 91 / Survey of Computers in Manufacturing (2
): Confusion over the levels of integration and flexibility - Intelligent M
achine Tools, a different approach
By ANDREW BAXTER
IN the beginning there were machine tools, the workhorses o
f every
mechanical engineering workshop in the world, which are used for cut
ting,
grinding and shaping lumps of metal to form components for all sorts o
f
industrial products or machinery.
Then, over the past 25 years, came numer
ical control and computer numerical
control (CNC), in the form of user-frien
dly units attached to the machine
tool which can be part-programmed on line
by the operator or off-line in the
production engineering office.
Hand-in-ha
nd with the CNC units, whose software can control almost any type
of machine
tool, new designs of machine produced the higher precision,
stiffness and s
tability to take advantage of the greater accuracy that CNC
offers.
CNC, whe
n applied to single machine tools, is well-established, and more
than 80 per
cent of Japanese machine tools are numerically-controlled. The
units are po
werful enough to control 'machining centres', which can often do
the work of
eight or more standard machine tools, and may contain more than
100 differe
nt cutting tools.
As the cost of computing power has come down, the economic
s of computer
memory storage have been transformed, and CNC units can store
and recall
hundreds of different instructions for a great variety of workpie
ces.
From the mid-1980s, further developments in CNC technology have produce
d the
concept of a 'flexible manufacturing system' (FMS), two or more machin
ing
centres linked and coupled under the control of a host computer. The
imp
ortant word is 'flexible,' according to the UK Machine Tool Technologies
Ass
ociation: 'The combined power of the machine and host computer, and their
st
orage memories, is enough to manufacture all prescribed varieties of work,
i
n any order.'
FMS is now being being linked to computer-aided design and pro
duction
control to produce manufacturing industry's Holy Grail, Computer Int
egrated
Manufacturing (Cim).
The aim is to link 'islands of automation' on t
he factory floor with all the
other computerised functions of the manufactur
ing process, such as
purchasing, ordering, stock control and is proving to b
e a tougher challenge
than many in the computer industry had predicted only
three years ago.
Put at its simplest, there appears to be considerable confu
sion among
manufacturers about how integrated their approach to Cim should b
e, or how
flexible their use of FMS. The situation is not helped by a prolif
eration of
computer suppliers, all keen to sell their product but varying in
their
commitment to service and support.
Dr Norman Schofield, director of e
ngineering and systems at PA Consulting
Group, says there are very good tech
nical reasons why Cim has been difficult
for many companies to achieve.
Comp
anies had believed that, to stay competitive, they needed to buy the
best av
ailable computers for each of the many different disciplines in the
manufact
uring process - packaging, software, documentation, electronics and
mechanic
al engineering.
This, in turn, increased the size and complexity of the 'dat
a package'
describing the product, and spread the data over many systems.
In
one recent assignment, PA found 41 different applications used in a
company
's design/engineering process alone, on six different computer
platforms, on
10 sites in three countries.
The problem for the manufacturer, says Dr Scho
field, is whether it is going
to get independent advice from any of its comp
uter suppliers if it wishes to
integrate its systems. PA has attempted to he
lp clients through the maze by
building its own Cim centre using four comput
ers and 12 software
applications from nine different suppliers.
The aim is t
o illustrate the many elements involved in applying Cim to the
relatively si
mple task of putting parts on to printed circuit boards.
Dr Schofield believ
es that open systems will be the key to developing
progress towards Cim, and
says most computer vendors are prepared to accept
the inevitability of an o
pen environment.
'Manufacturers are getting a lot more help from suppliers,
which is all
leading to easier integration.'
However, he says manufacturers
can help solve their integration problems
themselves in two ways.
The first
goes back to the machine tool itself: manufacturers, if they have
the clout,
can insist that all their machine tool suppliers install the same
controlle
r.
Secondly, manufacturers have to accept that integrated systems can be too
heirarchical. 'Where you can have autonomy (in a flexible manufacturing
sys
tem, for example) you should let it happen. Some failed systems have
tried t
o make things too rigid.'
Indeed studies of the influence of FMS in the US s
ince the mid-1980s have
shown that it is often a misnomer, since the system
may be inflexible in its
design and the way in which it is used. Also severa
l reports have claimed
that systems installed in the US lack the flexibility
of those in Japan.
A recent report on the US FMS market by Frost & Sullivan
, the market
research publishers, says worldwide competition is forcing adop
tion of
flexible manufacturing in a variety of industries, but is becoming
i
ncreasingly important to batch-oriented manufacturers as product
life-cycles
shorten and product changes become more frequent.
F & S forecasts that sale
s of FMS equipment will rise from Dollars 266m in
1990 to Dollars 559m in 19
95 (in constant 1990 dollars).
The biggest obstacle to installing equipment
is price, and more companies
will be starting with the more limited flexible
manufacturing cells (FMCs).
In the UK, British Aerospace has taken a novel
approach to Cim by developing
its own manufacturing control system, Cimitar,
which provides a
sophisticated computerised link between management informa
tion systems and
shop-floor controllers.
BAe began the Cimitar programme in
1983 after discovering that computer
companies could not satisfy its large-s
cale requirement for shop-floor
control systems. A separate company, BAeCAM,
was set up in 1988 to develop
and market Cimitar worldwide, but Mr Brian En
twhistle, general manager, says
it was decided from the start to develop a g
eneric product that could be
sold on the open market.
Cimitar, which uses DE
C's Vax hardware, is in use throughout BAe but BAeCAM
recently signed up Cat
erpillar, the US construction equipment group, as a
user. Mr Entwhistle hope
s this will provide a reference for further US
sales.
BAeCAM has also instal
led part of Cimitar on to an IBM PC that runs a
machine tool at BAe, elevati
ng it from the normal download of data and
selection of tools and satisfying
the need for complex communications
between the tools and the host computer
.
As companies continue to grapple with the challenges of Cim, and consultan
ts
to explain them, its ascendancy is being challenged by another acronym, P
im,
product information management, alternatively known as EDM, engineering
data
management. Dr Charles Clarke of London-based Random Computing says tha
t,
just as Cim was the catalyst for integrating manufacture, so Pim forces t
he
user to understand the existing process before being able to manage it or
use it.
The characteristics of Pim/EDM, which has also been described as a
short cut
to Cim via Cadcam, include data management and control and data na
vigation
mechanisms, but the aim is enterprise-wide control of information.
This, says Dr Charles Clarke, liberates the user and allows true concurrent
engineering - designing a product and allowing its manufacture
simultaneousl
y - for the first time.
'It links the islands of automation that yesterday's
manufacturing industry
nurtured and constrains the 'paper flow' monster wit
h its attendant
road-blocks and bottle-necks,' he says with an enthusiasm fo
r metaphor
rarely found in studies of computers in manufacturing.
The Financial Times
London Page II Photograph The British A
erospace small parts flexible manufacturing system, Preston, England (Omitte
d).
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