Ergonomic Design: Work Intensity

 In Ergonomics

The word ergonomics comes from two Greek roots. The first being Ergo, meaning work or task. The second root is Nomos, meaning law or statute. When we put them together, we can see that the word ergonomics effectively means, “the laws or statutes of work.” However, in a practical application of the word, we understand that ergonomics equates to being the law of completing work safely and comfortably. Understandably so, that makes ergonomics incredibly important when designing a workspace or manufacturing floor to operate safely and comfortably.

There are many things to consider when designing ergonomically focused workspaces. Today, let’s consider the intensity of the work task. Generally, work tasks will fall into one of three categories: Heavy, Light, or Precision.

Heavy tasks involve large amounts of muscle force. Examples would be lifting heavy objects or manipulating semi-malleable materials manually, etc. Oftentimes these tasks can result in acute injuries, or eventually long-term Musculoskeletal disorders (MSD). To alleviate concerns of such injury from heavy work, the best approach is to arm the workers with some form of mechanical advantage. This can be manifested through applying lifting equipment or other mechanical assistance when performing the tasks. All to reduce the bodily stress felt on the human body. Tasks that require high amounts of force exerted by a human being should always be approached with caution. Implementing ergonomic machinery that alleviate human muscle exertion into the modern workplace is imperative.

Light tasks typically involve very little effort to complete. Examples would be securing bolts in a manufacturing process or applying adhesives. Despite these tasks being of lower intensity to the human body, they are not without risks. Generally, such light work tasks turn into a very repetitive rhythm with a relatively fast cycle time. Such repetitive tasks can, as a result, cause injuries to soft tissues sustained from the exposed repetitive motions. There are multiple ways to address the risks associated with repetitive motions found in the light work category. Ensuring that the work object is positioned properly with a suitable work positioning device will decrease the likelihood that workers experience pain in muscles, joints, tendons, cartilage, or ligaments. Combined with allowing workers more variety in their work tasks, will make their jobs more physically and cognitively constructive.

Precision Tasks require high degrees of physical precision and mental focus. Examples of precision tasks would be assembling small objects or soldering circuit boards, etc. These types of tasks generally require a great deal of dexterity to perform the task accurately. For precision work, it is imperative that the object be placed in an appropriate comfortable position in the range of shoulder to eye level, in order to reduce the stress on the neck, shoulders, and spine. An optimum work position can easily be attained by using a multi-axis work positioning device.

When designing or redesigning a modern shop floor, it’s important to consider the intensity each work task will exert on the workers’ body. Each genre of work requires different ergonomic solutions to provide safety, comfort, and employee health. No matter what work is done in your workplace, focusing on Good Ergonomics provides Good Economic results, manifested as reductions in injuries and rehabilitation costs, while simultaneously increasing production efficiency, quality, and overall employee satisfaction.

Frequently Asked Questions

How does work height change between heavy, light, and precision tasks?

Heavy work sits lowest, below elbow height, so the operator can use body weight and keep the load close. Light work sits near elbow height. Precision work sits highest, so detail can be seen without leaning in. One fixed bench height cannot serve all three.

What happens when a station is used for more than one intensity of work?

It gets set for one and compromises the others, usually by being set for the task that runs most often. Height adjustment is the fix, and it matters most on shared or high-mix stations where the task type genuinely changes through the day.

How do you classify a task that is both heavy and precise?

Handle them separately. Let the equipment carry and orient the load so the operator is not supporting weight, then set the working height for the precision element. That split is the main reason a positioner is specified rather than a simple bench.

Does lighting need to change with work intensity?

Yes. Precision work needs more light on the detail and less glare on the surrounding surfaces, while heavy work needs enough general light to see the whole load and the route around it. Lighting set for one can leave the other genuinely difficult to see.

Where does fatigue fit into this classification?

It changes which category a task belongs to over a shift. A task that is light at the start can behave like heavy work by the last hour, because the same load feels heavier as muscles tire. Classify by how the task feels late in a shift, not at the start of one.



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