Feature Warehouse safety Happy workstation, happy worker


Despite increasing numbers of robots and machines on UK’s production lines, people remain a key and important resource. Ross Townshend, an expert in manual production systems at Bosch Rexroth, examines how to make people more productive by focusing on workstation ergonomics


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recent study by the Health and Safety Executive stated that one million people every year are affected by musculoskeletal dis- orders as a direct result of poorly designed workstations. The impact on the bottom line for UK manufacturers was 11.6 million lost working days at a cost of £5.7 billion. With statistics like these, it’s no sur- prise the study of ergonomics is becom- ing more and more important in UK manufacturing. Done well, ergonomic design can increase motivation, satis- faction with resulting benefits in per- formance and productivity. However, it is still a badly under-utilised concept in industry, too often regarded as difficult to measure, costly to implement and low on the priority list.


Ergonomics is the study of human interaction with the environment, which in a factory consists of tools, equipment, working methods and the tasks an individual is being asked to perform. To implement an ergonomic solution, there are seven key factors that must be taken into account:


Body and working height Working at the wrong height can lead to a hunched posture, craned neck and strained eyes. Manual workstations must accommodate a range of body heights to ensure a tailored, rather than a ‘one size fits all’, approach is taken. The most important factors in the design of work stations are the work- ing height, proper sizing of reach zones, leg room and range of vision. It is vital operators have the opportunity to either sit down or stand up at their workstation, which Bosch Rexroth refers to as the “sit down, stand up” concept. “Sit down, stand up” pro- motes changes in posture, which reduce stress and increases perfor- mance, which is not possible with a solely sitting or standing workstation.


The work area height should always be between 800mm and 1,500mm. Working above this height, or above heart level, reduces the blood circula- tion and oxygen supply, leading to a drop in performance. Work that requires bending (below 800mm) can also hinder productivity and should be avoided.


Work area


Ergonomically designed stations reduce the risk of injury by adapting to fit the person instead of the other way around. No two workstations will be alike so it is imperative to find the correct working method for each individual to achieve the best results. Within the work area the following rules must be observed: 1. Avoid work above the heart; 2. Promote dynamic activities by avoiding standing still or static hold- ing which inhibits circulation and oxygen supply to muscles;


3. Allow for “stand up, sit down” concept or job rotation;


4. Minimise exertion through use of manual roller sections or lifting aids.


Reach zones


There are three rules to follow when designing an employee’s reach zone at their workstation:


1. Containers, equipment and operat- ing elements must be easily accessible and arranged in the optimum anatomic/physiological range; 2. Torso rotation and shoulder move- ments, particularly when under exer- tion (with weights of more than 1kg) should be avoided whenever possible; 3. A well-designed workstation should be set up into three zones. Primary; for equipment used constantly throughout the working day with equipment or tooling within easy reach when elbows are at an operator’s sides; secondary, for tools and parts that are often reached with one hand with everything


The correct adjustment of a table, chair, footrest and position of tools and material shuttles must be easily achieved


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being available within a 180 degree sweep of both arms when outstretched; and reference, for occasional handling such as reference files or transferring parts to the next workstation.


Parts presentation


The presentation of parts to the opera- tor is key in minimising physical exer- tion and unnecessary movements. The key issues to address are: 1.Frequently used grab containers should be placed at short distances 2. Heavy parts should be stored within easy reach in lower containers 3. Where possible use a slide rail or roller conveyor to minimise exertion


Range of vision


The work area height should always be between 800mm and 1,500mm for optimum performance


Each head turn or change in line of sight, results in lost time and decreases productivity. For the opti- mal workstation design, it is important to address every detail, including head and eye movement. Key vision issues for workstation planning are: 1. Avoid needless eye/head movements; 2. Vision distances should be as identi- cal as possible to eliminate refocusing; 3. Avoid fastening locations not visible to the operator.


Lighting


The correct light, adapted to the activ- ity of the workstation, is a basic prerequisite for high efficiency and quality. It is therefore important to: 1. Avoid strong lighting contrasts; 2. Avoid glare and reflection; 3. Ensure all workstations are free from shadows, flickering and glare.


Adjustment of work equipment To maintain performance levels and promote productivity, the correct adjustment of a table, chair, footrest and position of tools and material shuttles must be easily achieved. For example, Bosch Rexroth’s versatile aluminium structures ensure that tables, footrests and grab containers can be easily adjusted. What’s more, the correct sitting posture is vital with worker’s calves forming a 90 degree angle and appropriate lumber support. Specialist help and software tools are available at the planning stage to enable correct design before any material is ordered. Ergonomics starts with design, not adjustment of equipment on the shopfloor. Specialist planning and design tools, such as Rexroth’s MTpro, are available to help design of ergonomic workstations, to ultimately deliver a more efficient daily work rou- tine and benefit the bottom line.


MARCH 2013 Factory Equipment


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