Proceedings 19th Triennial Congress of the IEA, Melbourne 9-14 August 2015
Ergonomics and Lean Six Sigma integration. A systems approach
Isabel L. Nunes
Department of Mechanical and Industrial Engineering, Faculdade de Ciencias e Tecnologia - Universidade
Nova de Lisboa, Campus de Caparica, 2829-516 Caparica, PORTUGAL
1. Introduction
Competition, economic conjuncture and consumer-driven demand are some factors that are forcing
companies to adjust management strategies and to continuously improve performance. In such context
companies sustainability requires more than improving performance to keep up with competitors; it requires
overtaking them, which entails companies’ excellence, both on what they produce and on how they are
producing.
Lean Manufacturing and Six Sigma are major approaches to increase performance, since they focus on
reducing production waste, variability and costs (Dul & Neumann, 2009). Nowadays, these two
methodologies are frequently used together and designated as Lean Six Sigma (LSS).
However, such interventions can take a toll on workers (due to higher physiological and psychological
loads) since their goal is to maximize production minimizing resources, which can affect working conditions
(Pepper et al., 2003).
As a matter of fact, LSS is mainly focused on external (company) productivity but leaves internal
(human) productivity virtually ignored (Kelby Ergo Design, 2015; Zavitz & Smith, 2012).
Internal productivity regards the ability of workers to produce more with no increase in risk of injury or
errors, which is a key concern of Ergonomics - science that studies the human systems interactions, in order
to improve human well-being and overall system performance (IEA, 2000). Therefore, a solution that
maximizes performance combining external and internal productivities is one which integrates Ergonomics
and LSS, since they complement each other and can have a synergist effect. Contrariwise, if applied in a
cumulative but independent way, they can become conflicting, harmful to working conditions, and ultimately
detrimental to productivity (Nunes & Machado, 2007).
Ergonomics is most often housed in companies’ Occupational Safety and Health (OSH) department,
biasing managers to link its role to safety and not to effectiveness, performance or costs. Despite LSS and
Ergonomics share many common goals (e.g., safety, waste reduction, process improvement), usually
Ergonomics is not engaged in the business strategy process, particularly when Engineering and
Management embrace continuous improvement initiatives, like LSS (Monroe et al., 2012). This finding has
emerged mainly from field ergonomists, being marginally addressed by scientific literature.
The lack of studies on the integration of Ergonomics and LSS represents a gap that opens an
opportunity for applied research.
The purpose of this work is to present and discuss two successful case-studies, supervised by the
author where an integrated implementation of Ergonomics and Lean Six Sigma was performed based on an
adaptation of the DMAIC cycle which incorporates ergonomic tools and methodologies along the
improvement process.
2. DMAIC cycle
DMAIC is an acronym of the five steps applied in the improvement process: Define, Measure, Analyze,
Improve and Control. Such process requires these steps to be performed in the given order.
The basic DMAIC cycle, which is the core tool of Six Sigma projects, can be adapted with the inclusion
of tools and methodologies from the Ergonomics domain. The goal of adding these tools and methodologies
is to the improvement process is to allow it to encompass also the working conditions.
In the first step (Define), the ergonomic tools identified (e.g., checklists) and the data gathered from
existing records (e.g., injuries, accidents) is used to characterize the initial situation of the working conditions
and identify improvement opportunities.
The goal of the second step (Measure) is to establish the baseline. Therefore the ergonomic tools and
methodologies applied (e.g., RULA, NIOSH Equation) are meant to evaluate the status of performance
1 Proceedings 19th Triennial Congress of the IEA, Melbourne 9-14 August 2015
metrics in the beginning of the improvement process. These data will be compared to the performance
metrics at the end of the process to assess if an effective improvement was achieved.
The third step (Analyze) is the one where root causes are identified and validated. The root causes
have to be prioritized and selected for elimination on the subsequent step. The ergonomic tools and
methodologies used in this step are the ones which can help to pin-point and prioritize root causes affecting
the working conditions.
The goal of the fourth step (Improve) is to select and implement solutions which eliminate or, at least,
mitigate the effect of root causes. The ergonomic tools and methodologies selected for this stage are the
ones that help to identify cost-effective solutions, to test such solutions (e.g., SAMMIE Human CAD
modelling) and also to plan the implementation and to deploy the improvements.
The fifth and final step (Control) is meant to sustain the gains achieved during the process. This is done
through a continued monitoring process (e.g., checklists, questionnaires) and also by training. Once again
the main ergonomic tools and methodologies applied in this step are the ones designed to evaluate the
status of performance metrics.
3. Case-studies
One of the case-study was performed in a small company (Nunes et al., 2012) where a modified DMAIC
+ES
cycle (DMAIC ) including Ergonomics and also Safety principles was applied together with SAMMIE and a
ES
rule-based decision support tool (plus ) developed to monitor the implementation of the principles related to
Ergonomics and Safety. In this case the resulting improvement from a layout redesign was the combination
of 30% reduction in the lead time and a 10% increase in the process cycle efficiency with an increase of
working conditions, due to the elimination of manual materials handling.
Another case-study addressed the improvement of the production processes of a salting fish company
(Freitas et al., 2015). The improvements originated a 20% increase of the daily production. In one production
process productivity increased by 8.3% and the physical demand was reduced by 37%. In another process
the productivity had an increase of 100% while the physical demand was reduced by 44.4%.
This type of case-studies is helpful to bridge the gap resulting from lack of research on the integration of
Ergonomics and LSS which was previously identified. The case-studies, conducted in real world companies,
show that is possible to simultaneously obtain substantial gains in productivity (external) and improve the
working conditions (internal productivity).
Acknowledgements
This work was funded by Fundação para a Ciência e Tecnologia under the scope of project PEst-OE/EME/UI0667/2011
References
Dul, J. and W.P. Neumann. 2009. “Ergonomics contributions to company strategies.” In Appl Erg. 40(4):745-752
Freitas D., V. Nunes and I.L. Nunes. 2015. “Integrating Lean Six Sigma and Ergonomics – a case study.” In
Occupational Safety and Hygiene III - Selected Extended and Revised Contributions from the International
Symposium Occupational Safety and Hygiene (SHO 2015), Arezes, P. et al. (Eds), pp. 441-446, CRC Press/Balkema,
The Neterlands, ISBN 978-1-13-802765-7
IEA. 2000. Definition and Domains of Ergonomics. International Ergonomics Association. Accessed 31 March, 2015.
http://www.iea.cc/whats/
Kelby Ergo Design. 2015. How Much Waste Are You Still Missing By Doing Lean Without Ergonomics? Accessed 31
March, 2015. http://www.kelbyergodesign.com
Monroe K., F. Fick and M. Joshi. 2012. “Successful integration of ergonomics into continuous improvement initiatives.” In
Work, 41, 1622-1624
Nunes, I.L., N. Gouveia, S. Figueira and V. Cruz-Machado. 2012. “Integration of Ergonomics and Safety during Lean Six
Sigma Implementation.” In Riscos, Segurança e Sustentabilidade, Guedes Soares et al. (Eds), Lisboa 2:965 – 984
Nunes, I.L., V. Cruz Machado.2007. “Merging Ergonomic Principles into Lean Manufacturing.” In Proc. of the 2007 IERC
"Industrial Engineering's Critical Role in a Flat World", Bayraksan G et al. (ed), Nashville, Tennessee-EUA, 836-841
Pepper, L., M. Messinger, J. Weinberg and R. Campbell. 2003. “Downsizing and health at the United States Department
of Energy.” In American Journal of Industrial Medicine. 44(5): 481-491
Zavitz, B. and S. Smith. 2012. “Application of New Ergonomic Tools and Methods to Lean, Ergonomics and Six Sigma
(LESS).” In Applied Ergonomics Conference
2