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Ergonomics, derived from the root word ergon which means work and nomos which means laws, is the study of the related interaction of humans and the objects being used to perform a specific task, process, or function. It is considered system-oriented regulations and practices applicable to various facets of human activities. Its main concern is on optimizing human performances and well being at the same time achieving a desirable system output or performance.
In a simple term, correct ergonomic design will prevent humans or workers from repetitive or continuous injuries due to strain or stress on a specific part of their bodies, which if not corrected will lead to a possible long-term injury or worst, disability.
To achieve this objective, humans or the workers must “fit” to the given tasks or work. Their limitations and capabilities are given into account to ensure that the equipment, tasks, output information, and the environment will suit each worker.
To access the person and their related work, the ergonomists (individual specializing on ergonomics design) considers the tasks being done and its related demands towards the worker; the necessary equipment (shape, size, process); and the information being used (how it is accessed, changed, or presented).
Usually, ergonomists utilizes references from other field of disciplines such as mechanical engineering, industrial engineering and design, anthropometry, physiology, psychology, and biomechanics.
Often times, the principles of Ergonomic can be seen on the innovation of the equipment or machine, and the creation or enhancement of safety procedures. The field of ergonomics is actually divided into three major domains: The Physical ergonomics, which is concerned with the human physiological, anatomical, biomechanical, and anthropometric characteristics, as they are associated to specific physical activities.
Examples of which are the postures during work, layout of the workplace, health and safety, handling of materials, continuous repetitions of movement; the Cognitive part of ergonomics which is concerned with the mental activities such as memory, perception, reasoning and psychomotor responses, as these influences the inherent interactions between humans and the system (tasks, machines or equipment, and information).
Examples of which are the human and computer interactions, decision making, and mental work stress and work load; the Organizational ergonomics which is concerned in optimizing systems with respect to organizational structures, processes, procedures, and policies. Examples of which are ergonomics within the community, crew communication and resource, quality management, virtual organizations, and teamwork.
Aside from this three major domain, there are five aspects of ergonomics, which concerns on the following: Aesthenics – example is the signage used in the workplace in such a way that it would be pleasing and at the same time provides information will be very much accessible to the workers. Comfort – example is the design of an alarm clock should give emphasis on its contrast in the dark so that eyestrain can be avoided.
Safety – example is the labeling on the bottle of medicine should be ergonomically designed in terms of color and size of letters so that the patient with impaired visions can see more clearly the dosage. Ease of use – example is the street light should be strategically and visually located to be accessible to the motorists so that possible accidents may be prevented. Performance and productivity – example is the use of a specific machine in the sense that the worker must be ergonomically situated to prevent accident and maximize performance and productivity.
Consequences of ignoring ergonomics include some but not all of the following: strain and injuries, increase lost time, less output in production, high material and medical costs, absenteeism, increased probability of work-related errors and accidents, and low quality of work (Holland, 2000). History The foundation of ergonomics have been seen in the culture of the Ancient Greece around 5th Century in the design principles of their hand tools, and workplaces. Very eminent were the hand tools in the form of axes, adzes, cramps, vices, benches, planes, gouges and chisel, pliers, pincers saws, rasps, and files.
The usual handle at that time was made of wood and the antlers of reindeers were sharpened to create a sharp edge. The wooden handle was not smooth and has curvatures to fit the grip of the user. The sharp edge was almost tied to be perpendicular to the handle so that the worker’s arm can have a thrust on the object being cut. Since ergonomic was not prevalent at that time, the design of the handle as well as the orientation of the sharp edge illustrates the principle of ergonomics. These materials were used during 6000 BC then at around 3000 BC bronze and copper materials replaced the sharp edges.
Screw vices were eminent during the 17th century Roman and Greek period. pegs were driven unto pre-bored holes on top of the bench. Again these were made of wooden parts not until the early 19th century that it was replaced by metal cramps and the design was changed to a “G” cramp structure. Planes during the 17th and 18th century manifests carved decorations and scrolled handles. During the 19th century major improvements were made wherein double cutting edge and iron were designed to prevent tearing. Early hammers were in the form of simple hand- held stones and made of iron, bronze, and steel.
The early Romans used nails that lead to the development of the claw hammer at present (Marmaras, 1999). The evolution of power tools began in 1813, when a shaker in the name of Sister Tabitha Babbit, had a vision of a teeth ringing around a rim of the wheel spinning. This led to the development of the principles of sawing. Before Babbitt’s vision, sawing usually comprised of two-long ripsaws handled by two workers from one end to another. The spinning wheel were soon incorporated by circular blade then later on being run by machines through electricity rather than being actually performed by humans.
The principle of the spinning wheel design contributed to the innovation of the sawmill. Ergonomically, the two-long rip saw proved to be very inadequate for two workers were needed to accomplish the task. In the development of the spinning wheel, one person is only needed to accomplish the task enhancing productivity. In 1867, Wilhelm Fein developed the first power hand drill through incorporating a minute electric motor to able to drill. Ergonomically, both hands were used to hand drill cast- iron and heavy metals, and shoulder strap and breastplate were used to prevent injury.
Justus Traut, an employee of Stanley Rule and Level co. , developed the first ergonomically designed handles designed to make tools easier to hold such as block planes and levels. The patent was known to be the “Hand-y” grooves. Edmund Michel and Joseph Sullivan, in 1923, created a circular saw, which was in the form of a power hand tool to cut specifically lumbers, which was eventually called the “Skillsaw”. The evolution of hand and power tools is vast that only brief descriptions are given above. The principles of ergonomics can be seen on every design with emphasis on the functionality and
safety of the user. Innovations on the materials used were obvious and technology changes the type of materials, design, and procedures, in conjunction with sound ergonomics principles (Sanders, 1993). Ergonomics applied to Hand and Power Tools Tools are considered one of the equipment being used in everyday activities. Whether it is intended for work, house hold activities, or creating something during leisure times, the necessary knowledge on the nature of the tools, how it is being operated, its corresponding risks, and the proper ergonomic procedures should be considered.
Usually, tools are manufactured with safety taken into consideration when it is being used by humans or by the workers, but it can still possibly pose relevant hazards when used inappropriately. Tools are categorized into two parts: The non-powdered tools which includes screw drivers, pry bars, wrenches, axes, etc. ; and the power tools, which utilizes electricity to become functional, includes, hydraulics, electric- pneumatic, and powder actuated. The applications of Ergonomics manifested on the safety of the user and to their co-workers, to the quality of work and the overall process.
Hazards should be considered as a basis for an ergonomic recommendations and approaches. Hazards of Using Hand Tools The hazards of using hand tools may emanate from the user itself: improper handling and maintenance, and misuse. Ergonomic Recommendations Since the hazard on using hand tools greatly depend more on the nature and awareness of the user, the following ergonomic solutions are advised: • The worker or the user has a direct responsibility for the maintenance, proper use, and safe conditions of the hand tools being used.
• The workers must be trained that sharp ends of the hand tools such as those of knives and saw blades should be kept directed away from other nearby workers. • Scissors and knives should be kept sharp at all times since dull tools can be more dangerous than sharp ones. • The working area or specifically the floors should be kept dry and clean at all times to prevent workers from accidentally slipping with a sharp hand tool on their hands. • On working inside a flammable substance environment, spark-resistant tools should be made for hand tools such as aluminum, brass, plastics, or wood.
Power Tools Hazards When not properly used, power tools can cause harm and injuries, since it is utilizing electricity to operate. Ergonomic Recommendations • Avoid carrying the tool by using hose or cord. • Do not attempt to pull the hose or the cord to disconnect it from the receptacle. • Tools should be disconnected from the power source before charging or servicing parts. • Both hands should be used to operate the tool; secure the work with a vise or clamp. • Keep the finger away from the on button unless the tool is to be operated.
• Keep the manufacturer’s manual for maintenance instructions on lubrication and changing parts. • Always maintain good stance or balance when utilizing power tools. • Avoid wearing accessories that may interfere when using power tools. • Tag tools that are defective and keep it away from the working tools. Different ergonomic approaches are also considered on Guards, electric tools, powered abrasive wheel tools, pneumatic tools, powder-actuated tools, hydraulic tools, and jack hammers. Guard
• The safety guard should never be removed whenever a power tools is in operation. Electric tools • These tools should have a three-wired cord with the third wire being the grounding wire to avoid electric shock. • Always operate electric tools within the limit of their design specifications. • Always wear protective gloves, and safety shoes. • Store the tools in a dry and secured place. • Do not operate the tools on wet or damp places to avoid electric shock. • The working area should be well illuminated. Powered Abrasive Wheel Tools
These tools are used for cutting, grinding, and polishing where when utilized may throw off fragments that can harm workers. Whenever this kind of power tool is used, always bear in mind the following ergonomic recommendations: • Always use protection goggles for the eyes. • Do not stand directly in line with the front wheel not until it reached its full working speed. • The wheel should be inspected before mounting it to the tool. • Turn off the power when the tool is not in use. • Never use vise on clamping hand-held grinders.
Pneumatic Tools The different types of pneumatic tools are hammers, drills, sanders, and chippers, and usually use compressed air to operate. The hazard of which is that a worker may be stroked by one of the tools fastener or attachments. Given below are some of the ergonomic recommendations. • Always wear eye goggles for protection, ear buds for protection and a face guard. • The hose should be checked if it is fastened securely • A retainer or a safety clip must be installed to prevent the attachments from being drawn towards the barrel.
• Protective screens should be set up to protect nearby workers from the fragments • Avoid pointing pneumatic tools directly towards another person or workers. Powder- Actuated Tools This kind of power tools should be treated with extreme caution and only trained personnel can use such tools. Hydraulic Tools • Only use approved fire resistant fluid that can retain its properties when exposed. • Do not exceed the recommended manufacturer’s operating pressure. Jacks • All jacks must always have a form of a safety device that will enable the tool to stop.
• The load limit must not be exceeded. • Secure the base to be stable and on a level surface. • Proper maintenance should be observed: regular lubrications and checking on parts for damages. Given above are only some, but not all, of the safety procedures that must be observed in using hand and power tools. These relatively illustrate several safety practices based on the probable hazards among the workers. Since one of the major concerns of ergonomics is the safety of the workers, the procedures above “fits” workers and equipment to achieve desired result with minimal loss or injury.
Generally workers using hand and power tools can be categorized into three model groups: the professionals who are skilled on using such tools; the so-called itinerant worker who is considered to be skilled and trained but with less experience and mostly self-thought; and the last is the one who only purchased a power tool for home use with no professional training after all. Since the first model comprised the professional groups, they can be considered as a skilled worker having sufficient knowledge and training on using such tools.
Ergonomic considerations for such users should be emphasized on the safety functions of the tools such as limiting shields, retracting guards, safety catches, locks, and automatic stops. However, on the second and on the third model group, an awareness of the safety standards is a must aside from the safety features of the tools. These safety standards usually contained in the Occupational Safety and Health Hazards lists the minimal requirements on power hand tools. Examples of such are the following: Portable Circular Saws – These tools should be equipped with a guard below and above the base shoe or plate.
Swing or Sliding Cut-off Saws – these tools should be provided with a hood that will totally enclose the upper half portion of the saw. Electric Power operated tools – these tools should have double insulation or be grounded accordingly. Hand Tools – unsafe hand tools should not be given permit; impact tools should be inspected free of mushroom heads; wooden handles should be free from defects or cracks. Aside from the safety standards, practices and procedures for hand and power tools, several ergonomic innovations are being created to increase the safety of the workers especially for the third model group.
Several examples of ergonomic innovations on hand and power tools are the Craftsman’s Twin cutter (Fig. 1), the Arbortech Allsaw 150 (Fig. 2), and the Saw stop system (Fig. 3). These innovations, intended mostly for the third model group, provides safety, and improved functionality to achieve comfortable handles, better balance, and self-holding triggers. Fig. 1 Fig. 2 Fig. 3 Conclusion To eventually avoid the possible hazards associated in using power tools, the workers must learn how to recognize the relevant risks in using such equipment and its safety procedures on handling and using such.
All workers must be trained in using hand and power tools to avoid accidents. Safety helmets, goggles, ear buds, and uniforms must be provided to workers exposed on splashing fragments caused by the power tools. Hazardous areas where the power tools are being used should also be in consideration to avoid accidents. Different power tools innovations are now being considered to provide safety and functionality to those who are not a skilled user or worker. Over all, principles of ergonomics apply to broad applications: safety and innovations are some of the very applications of this in relation of utilizing hand and power tools.
REFERENCES
Hollands, James (2000). Engineering Psychology and Human Performance. Prentice Hall. Karl, Kroemer (2001). Ergonomics : How to Design for Ease and Efficiency (2nd Ed. ). Prentice Hall International Marmaras, Nathaniel (1999). Ergonomic Design in Ancient Times. Prentice Hall. Sanders, Mark and McCormick, Ernest (1993). Human Factors in Engineering and Design (7th Ed. ). McGraw Hill International. Stanton, Nate (2005). Handbook of Human Factors and Ergonomics Models. CRC Press Tilley, Alvin (2002). The Measure of Man and Woman: Human Factors in Design. McGraw Hill.
