June 2013 | Commentary | The Lean Supply Chain

Reducing Defects and Errors: Don't Make the Same Mistake Twice

Tags: Lean

Paul A. Myerson is Professor of Practice in Supply Chain Management at Lehigh University, and author of Lean Supply Chain & Logistics Management. 732-441-3879

One popular definition of insanity is "doing the same thing over and over again, and expecting different results." So why does that occur all the time in business? Whether it involves producing many items with the same defects, or continuous incorrect inventory counts, we keep shooting ourselves in the foot.

Although 85 percent of quality issues are reportedly due to process and materials, it is common practice in some organizations to accept operator error as the cause of a defect.

Operator error often indicates a deeper problem, however, and using that excuse not only prevents finding a true solution to the problem, but also creates fear and mistrust within the organization.

In supply chain and logistics, we encounter controllable performance failures such as shipping the wrong product to a customer, receiving an item incorrectly, and making data entry errors. All of these issues are avoidable.

The Lean manufacturing principle "Quality at the Source" states that quality is not only measured at the end of the production line, but at every step along the way. Under this principle, quality is the responsibility of each individual who contributes to the production or on-time delivery of a product or service.

Instead of focusing so much on final inspection, we should make it everyone's job to ensure they provide only good material or information to their customer—not just the ultimate customer, but everyone to whom they pass product or information to complete the next step in the process.

An Ounce of Prevention

We don't create defects and errors on purpose, so how do we avoid them? A concept known as Poka-Yoke or Mistake Proofing can help. A Poka-Yoke is any mechanism or process that prevents mistakes or defects by forcing the user to do a task only one way. An example of a poka yoke is the dispensing nozzles on diesel fuel pumps. They are larger than the nozzles used for regular gas, and will not fit into non-diesel vehicle tanks.

Here are some ways to apply Mistake Proofing and Standardized Work in supply chain and logistics operations:

  • Institute system-directed cycle counting at warehouses to improve inventory accuracy and get to the root cause of issues.
  • Use Six Sigma and Statistical Process Control to reduce process variation that can create waste.
  • Communicate with customers and suppliers via electronic data interchange to reduce errors and improve productivity.
  • Standardize processes to reduce variations. Instruct all workers to use the best practice method, and create visible reminders to ensure a task is done the same way each time, no matter who performs it.
  • Organize your workplace using the 5S method—Sort out, Set in Order, Shine, Standardize, and Sustain—for a clean, safe, efficient, and uncluttered environment.

If we can abandon the notion that "mistakes happen" and—instead of pointing fingers—get everyone involved to solve the problem, we can make progress toward reducing and eliminating defects and errors.

Parts of this column are adapted from Lean Supply Chain & Logistics Management (McGraw-Hill; 2012) by Paul A. Myerson with permission from McGraw-Hill.