RESEARH PAPER SUMMARY
BY VAISHALI GURJER
SUMMARY ON
Universal design of workplaces
through the use of Poka-Yokes: Case study and implications
Authors: Cristóbal Miralles, Raymond Holt, Juan A.
Marin-Garcia, Lourdes Canos-Daros, School of Mechanical Engineering. University
of Leeds (UK)
Received June 2010
Accepted September 2011
Summary submitted by VAISHALI GURJER, PGDIE 42, NITIE, Roll No. 100
1 Introduction:
The Poka-Yoke approach was
developed in the manufacturing industry as a way of improving productivity by
reducing errors using often very simple adaptations. This paper argues that, as
Poka-Yokes are designed to make life easier and improve the performance of
workers without impairments, they are closer to the philosophy of Universal Design
than to Accessible Design. This paper provides a case study demonstrating the
use of the Poka-Yoke approach in a sheltered work centre for disabled;
highlighting how they served to improve accessibility to work by fulfilling
Universal Design principles.
It will be demonstrated how this
management tool Poka-Yokes, initially designed to minimize errors and maximize
profit, also helps to achieve
social-employment integration in the most efficient possible manner,
thus allowing the incorporation of CSR practices in companies.
2 Literature review
2.1 Universal Design and the Workplace:
Universal Design seeks to avoid the need for special adaptations by
designing products and environments that can be used by the largest proportion
of the population possible. This approach emphasises capability rather than
disability, arguing that disability and exclusion arise from poor design, and that
design which requires a low capability threshold benefits everyone, not just
the disabled.
2.2 Poka-Yoke: The Poka-Yoke (a Japanese word that means mistake-proofing)
technique was first developed in 1961 by Shigeo Shingo. Poka-Yoke uses devices
on process equipment to prevent the human or machine errors that result in
defects, or to inexpensively inspect each item produced to determine whether it
is acceptable or defective.
The Poya-Yoke philosophy aims to
increase productivity by simplifying processes, making them more efficient,
reducing the number of errors that need to be corrected, and increasing the
overall efficiency of the system. In this paper, we argue that Poka-Yoke represents a suite of simple and relatively
inexpensive ways of improving access to work and the productivity and
performance of disabled and non-disabled workers, and a powerful tool for
implementing Universal Design in the workplace.
3 A representative case study
The case study was developed in a
Sheltered Work Centre for the Disabled that assembles different kinds of
products. SWD are a model of socio-labour integration for disabled people. Like
any other private firm, a SWD competes in real markets and must be flexible and
efficient enough; the only difference being that their staff must have 70% of workers
with some kind of disability.
3.1 Initial situation
Initially, the SWD used
individual workplaces, designed without any particular consideration for
disabilities, so that only a few employees could complete the entire assembly
process for most of the products efficiently. Most workers were efficient in
some steps of the assembly process, but had difficulties with one or more
operations, which made their quality yield and their efficiency low. Consequently,
the SWD could only assign a subset of tasks to each individual according to
his/her limitations, resulting in a low flexibility of the workforce where the
SWD was not able to adapt to demand fluctuations or new requirements from clients.
In many cases, the SWD was unable to capitalise on increased demand for a
client's product, due to the lack of flexibility in its workforce.
3.2 Focus
of the research
In order to test the validity of
our proposal, a staff of twenty workers was analyzed. The five workstations
with most incompatibilities were selected for use as a pilot study. Twelve of
the twenty workers had difficulty with the tasks at one or several of the five
workstations.
Focusing on these twelve workers
we got the initial data in which only 23 workstations were accessible, out of 60.
3.3 Introduction of Poka-Yokes to the workstations
This section describes the
Poka-Yokes introduced at each of the five workstations studied.
Workstation 1
The first workstation was
dedicated to packing different kinds of screws and parts in plastic bags. The
problem encountered in this activity was the requirement to count the amount of
parts and components as they were placed in the bag. The solution was simple
but effective: a board with as many cells as parts necessary. When
the board is full the worker puts the contents into the bag and has his work
done with no errors.
Workstation 2
The second workstation was
devoted to bending corner protectors for the furniture. The work is not
complicated, but only workers with big hands and accurate motor capabilities
could do it efficiently. The Poka-Yoke that was designed in this case consists
of a matrix where the protector, once reclined, is easily bent giving it the right
corner shape.
A second version of this
Poka-Yoke enables the bending of the protector with a single hand (albeit less
efficiently than with two hands), which makes this workstation accessible to
one-armed workers or those with side-mobility problems. Indeed, under the
initial conditions, this workplace was inaccessible to half the workers
analyzed, but with the Poka-Yoke in place, all were able to perform this job.
Workstation 3
In this workstation the raw
material is composed of rolls of stickers that have to be cut and packed in
sets of varying sizes. This required a high concentration from the
worker, and was the cause of many errors, since the number of stickers in each
set depended on the product and varied among 2, 5, 10, 14 or 25…
In this case the Poka-Yoke
consisted of a template where the roll of stickers is easily unfurled. This
template has a mark indicating the place where the roll should be cut for
containing the right amount of stickers; having a different mark for each
amount required.
Workstation 4
In this workstation, furniture
components were assembled. Part of the assembly process included the use of an
automatic screw driver to fix two of the components. The problem was
that some operators had complications when aiming the screw driver.
This problem was solved by
inverting the activity process, which is part of the Poka-Yoke philosophy, and
fixing the device instead of the product. The automatic screw driver is now
fixed, and the worker takes the components to assemble to a template that
guides the screw to the machine.
Workstation 5
This workstation assembles lamps
of different shapes and models for general furniture and kitchens. Initially,
this workstation design was not inclusive at all.
In this case several strategies
were combined to improve the overall accessibility of the workstation, based on
a selection of Poka-Yokes from Shingo (1986):
• The workstation used to be
untidy and a lot of time was lost looking for parts.
In the revised workstation, components are located
in assembly order and in coloured-coded containers.
•Two separate screw drivers with
different heads are provided, each the colour of its corresponding screws
container. This way, there is no need to change the screw driver head every
time.
•A rolling device was included
for the rolls of stickers, so that they can easily be delivered. The stickers
themselves were also redesigned, so that their shape indicated where they
should be placed.
4 Discussion
The best indicator of the quality
of approach is the decrease in inaccessible workstations, which could be
considered barriers to employment. Taking the five workstations and twelve
workstations under consideration, there were initially 37 incompatibilities,
meaning that 61.7% of available assignments were not possible. Following the introduction of Poka-Yokes, an
additional 21 possible work assignments became available. Only 15 incompatibilities
remain, meaning that just 25% of available work assignments were not possible.
This is a substantial improvement not only in the accessibility of the work
involved, but also in the flexibility of the work force.
5 Conclusions
This paper has illustrated that
Poka-Yokes are a potential tool for implementing Universal Design in the
workplace, the core benefit being that - by increasing the ease of a task -
they offer benefits to all workers, not just those with disabilities.
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