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September 14, 2011

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Lifting and handling and ergonomics – Don’t suffer tools

Gerry Wainwright examines the role of ergonomic tool design in helping reduce workplace accidents.

The effective use of ergonomically-designed tools undoubtedly has a major role to play in helping organisations achieve the aspiration of zero occupational accidents.

The science of ergonomics covers virtually everything we use in everyday life and is very clearly defined by the Institute of Ergonomics & Human Factors as “the application of scientific information concerning humans to the design of objects, systems and environments for human use”.  As a result, ergonomic design has a vital role in the prevention of occupational ill health, in addition to reducing injury and accidents.

This is especially the case with hand and power tools, where the design of every tool used for an activity should be based on its ergonomic properties – i.e. how it interacts with a specific task, such as manufacturing processes or maintenance work, as well as with the person. Risks can be minimised by ensuring that tools are both ergonomically designed and fit for purpose, and that all staff involved in their use are properly trained and fully aware of how the tool should be operated, as well as the equipment provided for specific tasks.

In this context, the term ‘using the right tool for the job’ carries added weight, as this approach reduces physical stress and fatigue for the user and helps maximise performance and the quality of the work being carried out. The consequences of using the wrong tool are clearly the reverse, with an increased risk of incident or injury being of greatest concern, especially when working in more hazardous areas, such as at height, or in confined spaces.

Design factors

Prevention is, of course, better than cure, especially when it comes to reducing risk by ensuring that ergonomics are considered when designing tools. Factors such as weight, size and shape, the actions of the tool, and surface materials and textures should all be taken into account.

It’s also important to avoid and reduce high-contact stresses, concentrations of force and static loading on a tool, as well as extreme or awkward joint postures for the user, repetitive finger actions and excessive vibration, all of which can contribute to occupational-health problems.

The shape and form of tools also need to be considered so that they complement the natural actions of the human hand, providing a mechanical advantage. Tools must suit all users, including both left and right-handed people and, at the same time, the design should act in harmony with the natural contours of the human hand. These factors become most apparent when comparing a quality, purpose-designed tool in one hand and its more basic counterpart in the other. Although the purpose-designed tool will most likely cost more, it is likely to last longer, be fit for purpose and, most importantly, be safe, comfortable to use and work in harmony with the person to reduce stresses and injury, while obtaining maximum work performance.

Hand tools

Examples of the tool categories where essential ergonomic design becomes most apparent include pliers and cutters, where considerations such as the leverage-cutting, or gripping power, finesse of operation and grip all need to be taken into account to reduce hand fatigue and strain.

If we look at wrenches, issues such as turning power and grip become prevalent, with the need for handles to provide a non-slip gripping surface for greasy or oily hands, as well as the need to insulate against cold temperatures.

Even more humble tools, such as punches and chisels, hacksaws, hammers, or pry bars need careful consideration in terms of ergonomics. Punches and chisels are particularly good examples of detailed ergonomic design, with manufacturers now offering products with soft grip handles that aim to improve the thermal sensation
in cold working environments and reduce strike vibration. Incorporation of a semi-spherical striking area into the head of the punch, or chisel helps ensure the striking force penetrates the centre of the tool, as well as helping prevent the head ‘mushrooming’ and thus ensuring tool integrity.

Power tools

The influence of ergonomics on the design of power tools has developed considerably in recent years, with numerous innovations including weight, noise and vibration reduction, as well as the introduction of glass-filled nylon housings to balance the weight of cordless tools to reduce fatigue and improve control.

Ergonomic grip design is especially important for drills, because the hand needs to support, guide, press and control the drill simultaneously, without changing grip and without stopping. In order to achieve this, the form of the drill grip needs to match the shape of the inside of the gripped left or right hand, and the contact areas of both the longest and shortest fingers must have an adequate area to exert their different control pressures. Finally, the shape of the closed hand should fit naturally into the form of the drill grip. Ergonomically-designed control triggers also benefit the user and reduce fatigue by enabling one-handed use and forward/reverse lever control to change the drilling direction.

Hazardous situations

Ergonomic design is an important factor to consider when hand and power tools are used in more hazardous scenarios, such as at height. Moreover, the greater the height, or more adverse the weather, the greater the risk of a lethal incident occurring. Regulations relating to safe working at height in the construction sector are well known – however, there is still the need to promote safety-at-height awareness beyond construction. Furthermore, dropped objects can harm not only people but also plant or equipment below, potentially disrupting operations and causing delays in time-critical scenarios.

Specific consideration needs to be given when working with tools at height. For example, multi-part tools, such as ratchets and sockets, should have systems to prevent separation, and all hammers should have steel or composite shafts, non-slip handles and a head-locking mechanism to prevent separation of the head from the shaft. In addition, all hand and power tools used at height should be connected via a tested and certified lanyard and attachment point to a tool bag, which, in turn, is securely and comfortably attached to the person, or nearby secure point. Furthermore, all of these factors need to be achieved without compromising the performance of the tool, enabling work to be undertaken unhindered. Thought also needs to be given to tools used in electrical installations, where both lanyard attachment points and lanyards must be insulated to the same level of protection as the tool grips.
Protection from foreign objects

Well-designed ergonomic tools are also important in maintenance and operational activities in confined spaces, where the need to mitigate the risk of Foreign Object Damage (FOD) and Foreign Material Exclusion (FME) is, arguably, most prevalent. Foreign objects include anything that doesn’t belong, such as tools, test equipment, debris, surplus fasteners, or personal items than can be left behind during operational or routine maintenance. Such foreign objects can easily damage jet engines, short-circuit electrical components, or contaminate food manufacturing processes, with potentially lethal results.

At its most basic level foreign-object damage prevention involves having the right tools for the job to ensure ease of use, and a natural, intuitive grip to minimise the risk of slipping and dropping. However, tool recognition is also an important factor in avoiding damage from foreign objects, which can be addressed through the use of high-visibility handles, grips, shafts and bodies for easy identification.

Storage

Good housekeeping, such as keeping work areas clean and, crucially, accounting for all tools and equipment on completion of a task, are also essential. Accounting for tools, or tool control – as it’s often referred to – is an intrinsic part of safety, and can also be seen in the context of good ergonomic practice. In simple terms this involves storing tools in a custom-designed tool storage system, with a dedicated compartment for every tool – be this a wrench, socket, or screwdriver – ensuring that everything is in its place at the start and end of a job. This allows instant visual recognition to determine any discrepancies, or omissions in the tool-box inventory.

At a more sophisticated level, there is a number of electronic systems available for tool control, which includes networkable asset management systems that provide tool accountability, a usage record and details of equipment calibration dates and serviceability. A recent development is fully automated tool control, which combines tool storage networking and inventory tracking technology into a fully integrated and automated system that removes the need for technicians to manually scan tools in and out of a tool cabinet.

Conclusion

It is clear that the science of ergonomics has an essential role in the design of hand and power tools to ensure their safety and that ergonomic design is about much more than having nicely curved handles! Ergonomic design is all about the interaction between the tool, task and technician.

To conclude, it is worth emphasising the crucial need for effective tool safety training to ensure the right tools for the job are used correctly, for their intended purpose, and that they are maintained and inspected on a regular basis. Last, but by no means least, the use of proper well-designed eye and hand protection for the specific tasks involved also needs to be considered. 

Gerry Wainwright is training officer at Snap-on Industrial.

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