January 2013

Correlations in between EAWS and OCRA

EAWS (European Assembly Worksheet) is a 1st level risk assessment method for biomechanical load of the whole body and upper limbs used mainly in manufacturing industries as a process design tool for preventive ergonomics and adopted in the production departments for biomechanical stress mapping purposes.
EAWS offers compliance with the relevant CEN/ISO standards and it’s structured in four sections, each one covering a specific risk area: Body Postures, Action Forces, Manual Materials Handling and Upper Limbs inrepetitive tasks.
Each section is designed to measure with a score the load level for a given task (workplace) according to the corresponding 2nd level risk detection systems: OWAS for the Body Postures ([2] and [8]), RULA and Snook & Ciriello for the Action Forces ([4] and [7]), NIOSH for the Manual Materials Handling ([3] and [6]) and the OCRA Index and the Toyota System ([5], [9] and [19]) for the Upper Limbs in repetitive tasks.
The introduction of section 4 is the main contribu-tion of EAWS to the ergonomic analysis landscape, considering that EAWS originated from AAWS (Au-tomotive Assembly Worksheet), which missed the
evaluation of the risk area of upper limbs.

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Interactive production planning and ergonomic assessment

Manufacturing industries are facing major challenges due to the continued aging of their workforce, which is caused by an increasing life expectation and de-creasing fertility rates. The demographic development is particularly considered as risk factor for work tasks that are associated with low autonomy and high physical task demands, for example automotive assembly [1], [2]. In order to keep the work-ability of older employees and avoid work-related musculoskeletal disorders, such as severe low back pain and carpal tunnel syndrome, manufacturers need to regard ergonomic principles of workplace design in early phases of production planning [3], [4].
Computer-aided simulation tools, such as digital human models (DHM), are considered to be very promising in the facilitation of pre-production planning and proactive ergonomic assessment [5], [6].
However, current DHM tools are often very complicated to handle and thus, it is mostly very time-consuming and inefficient to prepare human simulations for specific areas of application. Furthermore, it is important to assure that simulations of cycle times and ergonomic workloads are very precise and reflect reality quite well because analyses results may lead
to substantial investments in workplace (re)design [7].
Facing these practical requirements this paper will introduce the “Editor for Manual Work Activities” (ema) – a new software tool that reduces the effort for preparing simulations of human work and, at the same time, improves the accuracy of simulations. ema can be applied in various manufacturing environments with clock-cycled assembly lines and manual work stations, particularly in the field of automotive production planning.

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ERGO-MTM model: an integrated approach to set working times

Work measurement is definitively a difficult task, since we miss a clear and objective reference as for distances and weights, where we have the meter and the kilogram. To set a standard time of a given man-ual task the following steps are necessary:
 – Set a basic time
 – Determine the proper time allowances
 – Add allowances to the basic time to set a stan-dard time
A basic time is the time necessary to an average person, well instructed, moving at an average speed and paying an average effort to accomplish a task, under the hypothesis to work for an entire shift (ap-prox. 8 hours). These conditions (skills, speed and effort) merge into a factor named working perform-ance. When setting a basic time of a task with a time study, the analyst has to levelthe observed time using the normal performance as a reference (if the rated performance is higher thanthe normal performance, then the basic time would be longer than the observed time). For example, to calculate the basic time to walk 1 km, it’s necessary to observe a person walking 1 km, rate the performance and take his/her actual time to execute the task . Imagine that the stop-watch time is 800 s and that the rated performance is 110% (10% above the one of an average person walking without getting short of breath). The standard time to walk 1 km then would be 800 s x 1.1 = 880 s. If a person takes 880 s to walk 1 km, his/her performance would be exactly 100%.

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Ergonomic assessment of automotive assembly tasks with digital human modelling

The increasing global competition and changing demographic profiles amplify the importance of efficient design of work stations and processes that considers the physical job demands and the operators’ abilities. Good ergonomic design is not restricted to the current production, but should be considered during all phases of the product life cycle. Digital human model (DHM) simulations provide good opportunities for an integrated ergonomic design, particularly during pre-production planning. This article gives an overview on DHM used in production ergonomics and highlights two new approaches to enhance current DHM applications. The editor for manual work activities (EMA) helps to speed up and optimise human movement simulation. MTMergonomics is an ergonomic risk assessment tool for industrial engineers (and ergonomists) during the planning phase of the product development process, based on MTM process languages like MTM-UAS. The ergonomic assessment worksheet (EAWS) is a tool for the holistic evaluation of physical workloads. It is implemented in digital human models like Jack and serves as an ergonomic evaluation tool within EMA and MTMergonomics. EAWS serves as a common feature tolink DHM, EMA and MTMergonomics activities.

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Integration of time as a factor in ergonomic simulation

The Volkswagen Group is facing a big challenge due to a proceeding globalization of markets and an increasing competition. Decreasing product life cycles, the need of flexible production systems and the demographic change demand solutions to assure or rather expand the own competitiveness. Processes have to be created, which assure and support increas-ing demands concerning productivity and quality as well as ergonomics. In this case, an important aspect is the establishment of ergonomic design methods in the product life cycle. Thus it is possible to influence products and processes as soon as possible in order to reduce costs. However, ergonomic evaluations in phase of development and planning are often difficult. The huge amount of different process simulation tools and digital human models constrain a standar-dized examination of ergonomics. Furthermore, existing systems do not providethe possibility to in-clude the intensity as well as the duration of exposure for the calculation of an ergonomic index [1]. Only the intensity of physical exposure has been consi-dered with static methods like RULA, OWAS or NIOSH [5, 10]. Therefore, within a pilot project, the algorithms of the methodEAWS were transferred into an existing digital human model.

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Ergonomics and workplace design

Ergo-UAS industrialization: management of a massive amount of data to integrate ergonomics into product design and production processes Since 2007 Fiat Group Automobiles adopted UAS method to assign a basic time to execute a motion of an activity described on process sheets where produc-tion cycles are structured and measured with a stan-dard and universal system (MTM-UAS, Methods-Time Measurement). Furthermore, FGA has intro-duced an ergonomic method, EAWS, to calculate, for each work-station, the proper biomechanical load. The previous system, to set standard time applied a relatively constant allowance to each single motion (about 4÷6%), as a function ofbody postures and forces.
Ergo-UAS system connects UAS with EAWS be-cause to feed EAWS method is necessary to input a lot of ergonomic parameters (postures, forces, actions and grip, material manual handling, trolley pushing and pulling) directly on each row of UAS analysis. By the overall working tasks assignment to a work-station (line balancing), Ergo-UAS aims at control-ling and limiting the work-load within the compli-ance ranges set by ISO/CEN standard. Ergo-UAS determines an ergonomic allowance factor, which, added to the total basic time (UAS time) gives the so called standard time. The Ergo-UAS model ranges from a minimum allowance of 1% to a maximum theoretical value of 52%. For workstation under con-trol and well-designed the maximum allowance value is 13,5%.
The core challenges during Ergo-UAS implementa-tion and management are:

– Magnitude of data: UAS analysis, ergo characterizations, Fiat data-blocks, product validities, work cycles, production program (mix of production)

– Speed and frequency of change (business dynamic condition)

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Global ergonomics strategy in Volkswagen

The basic question deals with what ergonomics is about: on the one hand there is the workplace with the focus on workplace design and work organization and on the other hand the employees have to be con-sidered regarding to correct postures and motions (as an essential demand on qualifications) and beneficial motions with view toself-discipline [3].
There are different needs for action in terms of er-gonomics. First of all, the human factor described of health hazards and social influences cross one´s mind. But also legal aspects occupational health and safety act, EC directives, requirements from professional associations and the social codes are ones of the first ideas of ergonomics. Another mean occurs of the economic factors which deals with issues like opti-mization of production times, quality improvement, and deployment options for employees in the value-creation process and also wage agreements. As well normative parameters have to be considered which are detailed of agreed collective wages (e.g. ERA) and frameworks (e.g. Volkswagen Way). Finally, the often discussed demographic development, the de-veloping age structure of the workers and culture
changes build the social-culture factors [3].
Thus, there are a lot of components which deals with ergonomics contents and include a huge amount of activities in the occupational science. In this article the role of ergonomics in the Volkswagen Group and concerned fields of activity will be explained [3].

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La versione TiCon 3.09

La versione TiCon 3.09, modulo MTMErgonomics, è allineata alla versione 1.3.3-2013

A gennaio viene rilasciato

A gennaio viene rilasciato il nuovo pacchetto di formazione EAWS (versione 1.3.3-2013)