Quite often, we are challenged by our clients to help them justify the cost and effort of implementing an ergonomics process within their organizations. Sometimes we are justifying a particular project, and sometimes it's the entire process.
Manufacturing excellence initiatives are the key drivers of change in manufacturing today. The easiest way to recruit the required people and money is through those responsible for the organization's continuous improvement (CI) processes. If the goal is to modify a manufacturing process to reduce ergonomic risk, then align the activities with those of the CI team. To obtain support from this team, be sure your ergonomics process is both systematic and data-driven.
A systematic process for ergonomics involves five steps:
- Identify problematic jobs.
- Assess and measure the risk associated at each of the problematic jobs.
- Prioritize a list of problematic jobs based on the risk assessment.
- Identify countermeasures to the risks identified.
- Predict the impact of each countermeasure.
Steps 4 and 5 are the most challenging parts of the process. To overcome the challenge, concentrate your efforts on low-cost, high-impact engineering controls like workstation geometry, tool modifications and equipment retrofit, rather than "home-run," high-capital automation. Also, demonstrate the link from risk exposure to root cause to countermeasure to show how your improvement idea reduces the risk to the operator.
If the focus is on these two strategies, the impact will be greater. However, if you want to increase your ability to influence the approval of countermeasures, you must predict their impact on production and quality.
Value to Productivity and Quality (and Safety)
The mission for manufacturing excellence initiatives is clear: They must save the company money. The metrics used to drive cost reductions generally are in the realm of quality and productivity and are measured in seconds or units, in the case of production enhancement, and defect rate or rework in the case of quality improvement. Ultimately, they are expressed in dollars.
In contrast, the goal of ergonomics is to reduce injuries and illnesses, an area that does not fall easily into the metrics sheet for the manufacturing excellence leader. And while safety professionals know that reducing risk reduces the injury and illness incidence rate, the leap to predictable direct cost reduction is, at some level, a leap of faith, no matter how proven our track record is.
Much has been written about the argument that improved ergonomics supports operational performance. In 2010, Neuman and Dul published a review of 45 studies that appeared in peer-reviewed journals between 1988 and 2006. Of the 45 studies, 95 percent demonstrated a clear convergence between human well-being and operational performance. But, as with many scientific findings, there are skeptics. The clouds of doubt can be lifted, however, if a scientifically sound, data-driven approach is used. This type of approach measures the impact of ergonomic improvements on risk, and projects the impact on quality and productivity.
Though a systematic, data-driven ergonomics process will be considered credible by the Six Sigma black belt or lean manufacturing champion, credibility alone won't be enough to gain their support; you must demonstrate a link between their goals and the benefits of improved ergonomics.
Ergonomic Links to Productivity and Quality
The link between ergonomics and productivity and quality is established when ergonomic assessments identify specific task factors that contribute to ergonomic risk, such as awkward postures, forceful exertions and high rates of repetition. These are point-of-motion constraints, which harm production and quality by preventing workers from performing at their best.
In very basic terms, it takes longer to complete a task using an awkward posture than it takes to complete it using a neutral or more natural body position. For instance, if you were to pack your suitcase on the floor rather than at waist height, you are adding about 30 inches of movement to your task. These 30 extra inches cost you discomfort (pain in the long run), but they also cost you 0.8 seconds on the way down and 0.8 seconds on the way back up, for a total time penalty of 1.6 seconds. The time wasted doesn't seem like much, but if you take that same time-penalty scenario and apply it to a manufacturing task that involves packing three boxes per minute for 8 hours a day, you quickly see that those 30 inches of additional, non-value-added movement add up to a lot of time and, therefore, money.
The link to quality is easiest to demonstrate when you consider the impact of force on task completion. When force exertion requirements exceed established norms for repetitive tasks, the result is fatigue. This fatigue causes the quality of task performance to degrade and, as worker fatigue increases through the shift, results in increased defect rates.
A simple example is in securing what are known as "Christmas tree" clips to hold a wire harness in place in the frame of a car. If the force required to insert the clip into the hole is greater than the force a person is capable of repetitively exerting, the clips will not be completely inserted. If they are not in place, the wire harness is not secured, which means it can move around. If it moves around, it may create noise, it may impede the operation of the wire harness and it may cause undue wear resulting in its failure as time goes on. In the best case, the quality check catches the error and fixes it (this costs time). In the worst case, it causes a customer complaint. Both are penalties to the company's bottom line.
Fitting the Job to the Person
So how can we design the job, workstation, equipment and tools to fit people to allow them to work at their best? A compilation of research in biomechanics, physiology and anthropometry has provided limits and guidelines for proper design.
There are many ergonomic design guidelines and standards to consider, and trade-offs must be made when designing products and manufacturing processes. However, you can achieve a great deal by adhering to a few simple guidelines.
To address posture issues:
- Perform material handling tasks between knee height and shoulder height.
- Perform heavy assembly tasks at approximately waist level.
- Perform light assembly tasks at approximately belly height.
- Perform inspection tasks at approximately chest height.
To address force issues:
- Limit repetitive finger forces to less than 2 lb (0.9 kg).
- Limit repetitive hand and arm forces to less than 10 lb (4.5 kg).
- Limit repetitive back bending to less than 25 lb (11.3 kg).
Making ergonomics part of your manufacturing excellence arsenal just makes sense. By adhering to established ergonomics principles and guidelines, you create work that fits the capabilities of your workers. The end result is safer, more efficient, value-added and defect-free production: justification made easy.
James Mallon, CPE, is a vice president with Humantech, which delivers practical solutions that impact safety, quality and productivity. Humantech believes people make productivity happen. For additional information, visit http://www.humantech.com or call 734-663-6707. Mallon can be contacted directly at [email protected].