Applied Ergonomics 1981, 12.1, 13-17
Observing working postures in
industry: Examples of OWAS
application
Osmo Karhu*, Reino H'~rktinen**, Pentti Sorvali*** and Pentti Veps'~l~iinen * * * *
*
**
***
****
Department Manager, Ovako Oy, Helsinki
Director of Administration, Ovako Oy, Helsinki
Manager of Industrial Engineering, Ovako Oy, Imatra
Head Shop Steward, Ovako Oy, Imatra
A practical method for identifying and evaluating poor working postures, ie the Ovako
Working Posture Analysing System (OWAS), was presented in an earlier paper (Karhu
et al, 1977). The application of the method is here described by means of two examples.
One is a case study undertaken by members of an ergonomics training course, in which a
marked improvement in working posture was achieved by OWAS analysis of critical
activities. The second illustrates the effect of setting up a multidisciplinary group in order
to develop an alternative method for the installation and maintenance of steel mill
equipment. In both examples, application of the OWAS method led to improved posture
in the situations studied, and to the likelihood of its wider industrial use.
Introduction
The development work of the OWAS-method (Karhu
etal, 1977) was started in Ovako Oy I in 1973 and we are
now able to present some examples of how the OWASmethod is applied in practice.
The steel industry, because of its capital-intensive nature,
is struggling with problems created by the need to increase
productivity. One of the objectives in a situation like this
should be healthy, safe and productive working conditions
which would make people willing to work in the steel
industry. It is therefore important that ergonomics points
are observed in routine decision-making at all levels within
the organisation. In our company this philosophy is
encouraged by extensive ergonomics training, this being
based on management decisions at an operation policy level.
The Industrial Engineering Department, co-operating with
work safety personnel, is responsible for the ergonomics
training in Ovako. The effects of working postures in heavy
physical work has become the central object of study and
the OWAS-method has been established for this purpose.
Two examples, in which the OWAS-method has been
used, are illustrative of the progress in the use of the
method. The first example is of a training topic given to a
working group during a 7-day ergonomics course. The
second example is of the results achieved through planning
and redesign. The difference between these two examples
10vako Oy is a private company producing steel bars,
profiles, wire rod and pig iron. The company consists of
two profit centres including four plants in the southern
part of Finland. The head office of the company is in
Helsinki. The company employs 3500 people. The
company's turnover is about 650 million FMK.
0003-6870/81/01 0013-05 $02.00 ~) IPC BusinessPress
is that the first has been produced under the strong
influence of ergonomics thinking, while the second applies
ergonomics training in the planning work of technical
designers.
Bricklaying the deck of an electric arc furnace
In the Imatra Steel Works the raw material, iron scrap, is
melted for casting in electric arc furnaces. The deck of the
furnace is a round arc-like construction made of firebricks.
The arc is laid in a separate working spot on a mould. The
diameter of the arc is 5.3 m and a deck wears out in
approximately one week, A working group on an ergonomics
course selected this task for its training case study.
The ergonomics course consisted of a lecture period of
5 days followed by a period of 3 - 5 weeks during which
the training topic was studied. In the final two days the
case studies were reported and criticised as project-work
during normal working hours. During this ergonomics course
a working group of four persons (with representatives from
workers, supervisors and industrial engineering) decided to
apply the OWAS-method to their training topic. The working
group turned to the Industrial Engineering Department for
the study of working postures.
The study revealed that the bricklaying was done
primarily with the back in a bent posture (Fig. 1) for about
43% of the total working time. Particularly difficult and
hard on the bricklayer's back were the working postures
after the first layer of bricks were laid and the bricklayer
had to continue the laying work standing on the mould
with his back extremely flexed.
The study provided a new and different starting point
for the creation of ideas, and in co-operation with the
Industrial Engineering Department the working group
Applied Ergonomics March 1981
13
developed a 'ring-element' for the bricklaying (Fig. 2).
Each ring was fitted separately with bricks (Fig. 3) and the
rings were lifted by crane.
Following this change in the working method, tile check
study showed that the bent posture exposure time had
decreased from 43% to 22%. The new method has now
been used for nearly two years and the workers have given
their full approval to this corrective measure which they
consider a success.
Comparison of bricklaying with the new and old
method; OWAS-analysis
In the study the back, upper and lower limbs were
analysed. The most important result of this study was,
however, the comparison between operative classes 3 and 4
(Karhu et al, 1977). Operative class refers to urgency of
corrective action, 4 being the most urgent (Fig. 4).
From Table 1 we find that a definite decrease had been
achieved in those postures, which belong to classes which
imply a most urgent need for correction.
Trolley for adjusting guides in a roll stand
The objective of the working group was to develop
alternative working methods for the maintenance and
installation of a roll unit.
Fig. 2
Ring elements for bricklaying the deck of an
electric arc furnace. The mould consists of three
elements which fit into one another. The diameter
of the outer ring is 5.3 m and the total assembly
weighs 5000 kg
Fig. 3
Each ring element is fitted separately with bricks.
This allows the use of more acceptable working
postures
The rolling of billets in the Light Rolling Mill is carried
out by roll stands. In the Medium Section Mill the three
high mills together with bearings and rest bars form a fixed
Fig. 1
The old method of bricklaying. The first layer of
bricks is being laid
14
AppliedErgonomics
March 1981
(3)
(2)
(1)
IBACKI
(4)
I)
,dl• I
straight and
twisted
bent
straight
bent and
twisted
Old Method %
18,5
42,6
1,4
12,7
New Method %
43,5
22,3
2,9
2,2
(1)
UPPER
LIMBS
(3)
(2)
both~l iJ
limbs .8 k
limbs~ ~ .
above shoulder
on or below
shoulder level °~ao°u~~1b°~eevei level
both
|
I Old Method %
64,1
10,0
1,1
New Method %
63,3
6,9
0,6
LOWER
LIMBS
(2)
(1)
Fig. 40WAS-analysis of the old and
new method of bricklaying
(5):
(4)
(3)
/
/
"I'P
Old method %
New method %
loading on both loading on one loading on both loading on one body is moved
limb, bent
by the limb
limbs, straight limb, straight limbs, bent
12,1
4,7
48,0
5,4
5,0
6,8
54,9
Table 1
Operative class
2
3
4
Old method
13.9
3.2
5"6
New method
7.2
1.5
0"6
roll stand. With the help of guides the billet is guided into
the groove. The maintenance and adjustment of the 30 ton
roll unit is done in a separate working area, where the unit
is lifted by crane (Fig. 5).
This is an example of setting up a working group to solve
a certain problem. The working group comprised six people;
a planner, an industrial engineer, two supervisors and two
1,3
0,2
7,7
workers, and the group reported their results to the
co-ordinating group (a department manager, representatives
of supervisors, workers and the Industrial Engineering
Department).
Table 2 shows the ergonomics training situation at the
time of the study at Imatra Steel Works. In addition to the
training shown in this Table, members of the working group
were given a 1 - 4 h lecture during rationalisation and work
safety seminars.
Comparison of the old and new methods of working
The old method for adjusting the guides was carried out
on a fixed mounting stand in the rolling mill hall. This
situation was hot, noisy, the air was dust-laden and draught
Applied Ergonomics March 1981
15
was continuous. The working postures were difficult and
included stretching and bent postures as well as lifting of
heavy objects. The new method allowed the installation
work to be carried out in a van with an adjustable working
platform.
have not succeeded in eliminating all poor postures but some
of them can further be eliminated by making small changes
in the trolley (Fig. 7).
Conclusion
A comparative OWAS-analysis (Fig. 6) shows that
working postures changed from bent postures (2) to
straight and twisted (3) and bent and twisted (4), but the
share of operative class 4 had decreased by about 50%. We
Because people should be considered as 'units' it is
important to observe working postures as a unit by
combining the postures of the back and limbs in one
observation and analysing the working posture as a whole
(Fig. 8).
Table 2
Course
Persons
In the two examples presented the main consideration
has been on the reduction of 'bad' postures and their time
share. Two more considerations should be taken into account
Total
I matra
Steel
Works
Co-ordinating Working
group
group
(a)
(b)
Ergonomics course
(7 days)*
2
1
77
OWAS-course (5 days)*
1
1
25
Ergonomics course
(4 weeks)**
1
reduction of posture-caused disorders or diseases,
and
productivity.
We have no indication that back pain or other locomotor
organ disorders have been diminished. The small number of
subjects and insufficient follow-up time do not allow that
analysis. Because back pain is often multicausal, we do not
expect that even with a greater number of subjects a
measurable effect could be achieved. We expect that good
working conditions will lead to better health and lower
absence figures in general.
11
*Internal training
** Course by the Institute of Occupational Health
Also the productivity in the two examples is made up
of several factors from which the purified effect of
correcting working postures is not easily separable. In the
bricklaying, the total working time decreased by 10%,
which seems to come directly from the lightening of the
working postures. In the roll stand guide's adjustment task
the shortening of the total time is 25%. The concurrent
partial mechanisation of the task assists in the shortening
of the work time, so that the sole role of changes in working
postures is not easily distinguishable. The stand-up time in
the rolling mill line shortened considerably. The quality of
the reassembly has definitely become better and we regard
this as a direct effect of the easing of working postures.
For practical purposes the separation of the effect of
change in the working postures and in technical equipment
and methods is not very interesting, if we recognise that
there cannot be a good and productive technical system
without consideration of the human aspects.
Fig. 5
Until now, the use of the OWAS-method has been rather
selective. In addition to the direct results provided by these
studies, they have achieved indirect results by making
attitudes more favourable towards working postures.
A diagram of the 30 ton rolling unit. Maintenance
and adjustment mechanisms intcude rest bars (B)
and guides (G). With the help of guide (G) the
billet is guided into the groove
(1)
,'A
(I
k
I
.41
straight
(4)
(3)
(2)1
i t
straight and
twisted
bent
Operative
Class
~J
Fig. 6
bent and
twisted
Old method (min)
186
60
4
6
15 min
New method (rain)
119
28
25
14
8 min
16
Applied Ergonomics
March 1981
A comparison by OWASanalysis of adjustment and
maintenance on the rolling
unit with the new and old
methods of work
(3)
(2)
(1)
UPPER
LIMBS
?he L
both
L
limbs ""
on or below
shoulder level
on or above
shoulder level
OLD METHOD (MIN)
198
40
18
NEW METHOD (MIN)
137
34
15
LOWER
LIMBS
/
(2)
(1)
l)
both
L
li
above shoulder
level
(3)
j'
(4)
(5)
(6)
4
d~
loading on both
limbs, straight
loading on one
limb, straight
loading on both
limbs, bent
loading on one
limb, bent
loading on one
limb, kneeling
body is moved
by the limbs
OLD METHOD
134
10
42
4
10
53
NEW METHOD
118
19
16
5
--
26
Fig. 7
OWAS-analysis of positions of the upper and lower elements, before and after modification of maintenance
procedures on the rolling mill unit
AN EXAMPLE
POSTURE 2t 5
"•••ECTIVE
BRICKLAYING
THE DECK AN
ELECTRIC OVEN
ADJUSTING THE
GUIDE IN THE
ROLL UNIT
OLD METHOD (MIN)
1 4,0
1,5
NEW METHOD (MIN)
0
0,5
METHOD
Further information on the OWAS-method in Ovako Oy
can be obtained through Mr Osmo Karhu, Ovako Oy,
POB 790, SF-00101 Helsinki 10, Finland.
In December 1975 Ovako Oy conveyed the OWASmethod to the labour market organisations (The Finnish
Employers' Confederation and The Central Organ!sation of
Finnish Trade Unions). The organisations have organised a
project, financed by SITRA (The Finnish National Fund
for Research and Development). This project aims at finding
BACK: bent
UPPER LIMBS:
both below
shoulder level
LOWER LIMBS:
loading on one
limb, kneeling
Fig. 8
Total time involved in Working
Posture 215 in (a) bricklaying
the deck of an electric oven
(b) adjusting a guide in the
rolling unit
out the possibilities of applying the OWAS-method to other
fields of industry. The project will be completed at the end
of 1978.
References
Karhu, 0., Kansi, P., Kuorinka, l.
1977 AppliedErgonomics, 8.4, 199-201. Correcting
working postures in industry. A practical method for
analysis.
Applied Ergonomics
March 1981
17