Lean manufacturing has replaced mass production for almost half of all U.S. manufacturers. Lean has helped employers improve operating efficiencies and retain manufacturing jobs in the States.

Unfortunately, many of these employers have seen their workers' compensation costs skyrocket after implementing lean concepts. For example, an automobile manufacturer experienced a 100 percent increase in cumulative trauma disorder (CTD) cases and received a Cal/OSHA citation for "insufficient attention to ergonomics" after implementing lean during a changeover of one assembly line in 1993.

That same automobile manufacturer implemented lean on a second assembly line model changeover and integrated ergonomics into the process in 1995. The result? The changeover was completed in 38 percent less time, achieved similar productivity gains and quality improvements, and reduced the number of injuries by 30 percent on this line.

Risk control processes must evolve to anticipate and effectively manage cumulative trauma disorder (CTD) risks that arise in the lean environment. Since lean and ergonomics share the goals of eliminating waste and adding value, there are natural ergonomic integration points in most lean processes. Ergonomics is simply another tool that can be used to make your lean processes more successful. Let's look at how ergonomics can help you achieve your lean objectives.

Applying Lean Processes

Lean manufacturing processes seek to create value and minimize waste to achieve a higher return on your capital investment. Using multi-disciplinary Kaizen teams, lean companies evaluate workstations, production cells, and entire assembly lines to streamline operations and eliminate waste. The seven key wastes that lean processes seek to eliminate are:

  • Correction - repair and rework

  • Motion - any wasted motion to pick up or stack parts, long reaching distances, unnecessary long walking distances, etc.

  • Overproduction - producing more than is needed right now

  • Conveyance - unnecessary movement of materials or finished goods into/out of storage or between processes

  • Inventory - maintaining excess inventories of raw materials, parts in process, or finished goods

  • Processing - doing more work than necessary - redundant material handling, unnecessary grinding or finishing, etc.

  • Waiting - any non-work time, such as waiting for parts, looking for tools, reaching for materials, etc.

By reducing waste in these key areas, significant cost savings can be achieved. This cost savings enables U.S. employers to compete in the global marketplace despite our higher labor costs.

Unfortunately, lean processes can make jobs highly repetitive while eliminating critical rest time for employees. When ergonomics is not integrated into the process, the repetitive jobs take their tolls on employees as stressful postures and high forces are repeated over and over throughout the day. In the long run, the financial savings from the productivity gains and quality improvements are used to fund the higher cost of CTD claims. But, as we noted with our auto manufacturer example, higher rates of CTDs are not inevitable.

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