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The Ergonomics Checklistfor Manual Work Systems

A guide to the design of ergonomic workstations

Bosch Rexroth AG�

A working surface which is slightly too low, a part which is positioned slightly beyond the employees’ reach or inade-quate lighting – these apparently minor factors can have a negative influence on employee efficiency, safety and motivati-on. This in turn has a direct effect on the productivity and manufacturing costs. In fact, in the view of many experts, the amount of productivity lost as a result of the conditions described above is grea-ter than that caused by actual illness.

To enable you to obtain maximum em-ployee efficiency, safety and job moti-vation – and consequently productivity – Rexroth has produced this brochure on workstation ergonomics. Based on the seven fundamental rules of ergonomic design this brochure will serve as your guide for the design of workstations to suit every employee and every task.

Why adapting the workstation to suit task and employee is important

Properly designed workstations increase both employee productivity and job motivation as well as product quality.

The FMSsoft software, based on the AutoCAD® system, enables you to quickly and easily adapt workstations to suit the needs of the employees.

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1. Taking body size into account

The height of the worktop surface must be suitable for employees of differing si-zes. The standard Rexroth work-stations are designed for a range of heights that covers 95% of all adult female and male sizes. Specially adapted workstations are also available.

When selecting the workstation height you should observe the following:

Ensure adequate freedom of movement beneath the desk (for seated/standing workstations the following applies:

foot room depth > = 550 mm, leg room depth > = 350 mm). Avoid obstacles such as drawers bet-ween the upper thigh and the underne-ath of the desk surface.

The size of the workpiece on the desk influences the employee’s posture. When carrying out work that is very demanding on visual monitoring and the motor functions the working position should be higher than for activities that place minimal require- ments on visual monitoring and demanding requirements on arm freedom of movement.

Take up various sitting positions, depending upon the task of work. – Forward seating position: bending slightly forwards (assembly work that requires

force). – Central seating position: upright

(assembling small components, testing).

– Rear seating position: leaning slightly backwards (testing, monitoring).

Use our planning software (FMSsoft) which takes into account various sizes as well as the relevant standards and guidelines.

Rexroth workstations take account of the differing body sizes

Visual distances and lower arm positions shown according to varying body height and working height

Seated and standing workstations

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2. Testing the area of reach

A distinction can be made between three areas of reach at the workstation:

– maximum area of reach, – optimum area of reach and – area of reach with both hands.

All components, tools and all accesso-ries should fundamentally be positioned within the employee’s reach. Having parts within easy access avoids the need for turning the body, the arms and bending and twisting wrist joints when reaching for parts, consequently reducing extreme stresses and injuries that occur as a result of one-sided and repeated movements.

The supply of components should be planned on the basis of the following criteria:

Area C Mountings and containers with the most frequently used components should be positioned within this area as this is where both hands work within the field of vision.

Area B Parts and tools which are frequently collected with one hand should be positioned here.

Area A Do not position grab containers outside this zone which can be used to extremely beneficial effect.

Area of reach for a woman 1660 mm tall (woman of medium height).

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3. Optimise the layout of parts containers and the material flow

Optimise container layout in order to reduce superfluous movements and to speed up the parts flow rate:

Containers with the most frequently used components should always be easily accessible with minimum movement (within close grasp).

Heavy components should be located in lower containers on the work surface. Reason: it is less tiring to remove components from the container parallel to the work surface than to remove components from an upper container and place them onto the work surface.

Where possible position all containers within the optimum area of reach B.

Make use of the facilities for working with both hands in order to save time.

Select container sizes to match parts geometry and quantities. Pay heed to the area of reach in order to minimise the reach of and the need for the employee to

turn his/her body.

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Arrange for all work to be carried out below heart height in order to improve the blood circulati-on

Observe the following basic rules:

Avoid positioning workstations above heart height, otherwise the blood circulation will be reduced, resulting in a rapid drop in the employee’s performance.

Avoid tasks which involve static holding during assembly, otherwise the supply of blood to the muscles will be reduced and muscle tiredness will increase. This in turn will result in a fall in the coordination capability, one of the main factors for poor product quality.

Use seated/standing workstations and group workstations in order to enable the workload to be alternated.

Avoid activities which involve static holding, because otherwise the supply of blood is restricted.

4. Avoid positioning workstations above heart height

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The ergonomic requirements for the field of vision should be taken into account for the purpose of optimum workstation design:

Avoiding unnecessary head and eye movements saves the employee having to repeatedly refocus his/her vision, an action that puts a strain on the eyes.

Provide for a natural head position (when standing 15°, when sitting 25° angled towards the horizontal).

Arrange frequently required materials within the optimum field of vision A (objects can be easily identified by eye movement without the need for head movement).

Where possible, do not arrange materials outside the maximum field of vision C (objects can be identified without head movement).

Position the containers at the same distance. The employee’s eyes will then not have to refocus on differing distances each time there is a change in the angle of vision.

Reduce angle of vision to less than 35° (B)

Limits of the maximum field of vision (B)Limits of the field of vision expanded by head movement (D)

5. Take account of fields of vision

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6. Adjust lighting to suit the task

Proper lighting is extremely important. The correct lighting for a specific task reduces errors and increases the employee’s performance. A number of guidelines for adapting the lighting to suit the specific task are shown below:

For most tasks the standard light intensity is 500 Lux

For specific viewing tasks 1000 - 1500 Lux is required

General positioning task Detailed positioning task

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7. Adjust working aids to correct setting

Desk, chair, foot support, container, tool preparation, material trolleys and box lifting equipment settings should be adjusted to suit the requirements of the employee and his/her task. Correctly adjusted working aids reduce strain and downtimes and simultaneously increase productivity and performance. The ergonomically designed Rexrothcom-ponents for workplace fitting-out form a co-ordinated system.

Utilise the adjustment facilities to mainta-in an economic and fatigue-free posture:

Place components and tools at the correct height and distance: shorter access times thanks to closer access positions.

Ensure correct chair and foot rest position: upper and lower thigh should form a right angle.

Position movable material trolleys within reach and angle them in such a way as to enhance accessibility.

Use box lifting equipment to avoid fatigue when positioning heavy components.

Correct adjustment of the workstation to suit the employee

Correct adjustment of material trolleys to suit the employee

Adjustment tosuit individual requirement:1 = Hight2 = Depth3 = Angle

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Optimumaccess range

FMSsoft planning software for the design of ergonomic workstations

Rexroth supplies system integrators, equipment distributors and end users with an efficient 3D software package based on AutoCAD® that offers impro-ved project transparency and conse-quently reduces the specification time and increases the order precision for workstation design. The FMSsoft plan-ning software uses icons or menu points and parameter-aided programming tech-niques so that assemblies, 3D models of humans or individual components of the Rexroth equipment for ergonomic workstations, can be quickly incorpora-ted into a 2D or 3D drawing. Selecting technical features and inserting properly scaled drawings gives you a precise re-ference to actual reality.

The high quality display of the human form is one of the FMSsoft elements. This enables workstations to be ergono-mically planned, tested and optimised to suit every body size.

The software can be purchased from your local Rexroth authorised dealer.

Presentation of the optimum access range.

Ergonomics Checklist 3 842 525 794 (2004.02)

Info Fax: +49 711 811-30364 Bosch Rexroth AG

Linear Motion and Assembly Technologies

www.boschrexroth.com/brl

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AustraliaBosch Rexroth Pty. Ltd.3 Valediction RoadKings Park, NSW 2148, SydneyTel. +61 2 9831 7788Fax +61 2 9831 5553

Great BritainBosch Rexroth LimitedCromwell RoadSt. Neots, HuntingdonCambs. PE19 2ES Tel. +44 1480 223 298Fax +44 1480 470 789

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© Bosch Rexroth AG 2004Printed in Germany3 842 525 794 (2004.02)EN • BRL/MKT4

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Bosch Rexroth AGLinear Motion and Assembly TechnologiesPostfach 30 02 0770442 Stuttgart, GermanyTel. +49 711 811-30698Fax +49 711 811-30364www.boschrexroth.com/brl