Lean Manufacturing Principles: Plan, Do, Check, Act


November 5, 2015

Lean manufacturing

To be the best at something requires patience, determination, focus, and constant improvement.  Toyota aimed to be the best when they developed practical methods of applying the lean methodology to manufacturing after World War II. Benefits of lean include:

  • Reduced waste and rework
  • Reduced costs
  • Faster production time
  • Faster changeover times
  • Improved overall efficiency
  • A bigger bottom line

The American Society of Quality defines lean manufacturing as “the elimination of all non-value-adding activities and waste from the business.” One way to accomplish lean is through continuous improvement, that is “ongoing effort to improve products, services or processes.” In other words, we don’t employ lean principles and say we’re done. The lean process is long-term and requires ongoing effort to be successful.

A common continuous improvement cycle is the following method:

plan > do > check > act

Plan—Mindset Change

Mindset change means that the many groups that make up a production facility must change their ways of looking at what they do. These groups include suppliers, design and production engineers, controllers, part fabricators, assembly, shipping, HR, and management. All of these groups must be on the same page about lean manufacturing.

Of these groups, management must take the lead for all change activities. Managers must be familiar with lean principles and take advantage of the current thought on the subject, including the 7 Wastes, Just in Time, and other basic ideas. Then, they can accurately pass along information to instill lean principles proficiently in the above groups. Methods of transferring information include traditional training, education, and incentives.

Do—Standard Work Instructions

Employees, machines, and tools are the key elements of any shop. For lean improvements, utilize the 5S plan for manufacturing (sort, set in order, shine, standardize, and sustain) and Total Productive Maintenance (TPM). The results yield better flow, reduced maintenance bottlenecks and machine downtimes, more organized and proactive repairs, and increased awareness of safety and waste.

Machining and parts assembly should follow the most logical process sequence, basing the rhythm on takt time and production rates. Together, these help ensure synchronization and best flow. Placing employees with multiple skills on the line helps overcome fluctuation in production.

Check—Verify the Process

Conducting Layered Process Audits (LPAs) are a good way to determine what is happening after a change in mindset and experimenting with changes on the shop floor. The auditors in the LPA process include personnel on many levels, which provides a complete audit. What’s more, because you receive input from many people, managers, supervisors, and production workers, LPAs provide varying viewpoints. The audits and the feedback you receive allow you to formulate a thorough view of the all of the activities in your facility.

Conducting Gemba Walks is an inexpensive and efficient way to see, firsthand, what processes work and which don’t. Rather than sitting at your desk and using graphs, statistics, and charts to try to improve things, you can proceed to the factory to observe processes and interact with shop personnel.

Act—Make it Permanent

Now that you’ve laid the groundwork, take permanent action:

  • Make the lean principles that you studied and passed on to the groups in your facility a permanent way of looking at the entire enterprise and its partners.
  • Make the lean improvements on the shop floor permanent. This includes any change in in production time, changeover time, transportation, repairs, safety, and waste reduction.
  • Make LPAs permanent. This means employing the structured LPA teams you created to continue auditing in an on-going effort to monitor shop activities toward improvement.

Perhaps the biggest challenge after your facility becomes lean is making sure it stays lean. This requires ongoing monitoring and analysis. But as we’ve seen, this is fundamental to the lean process. If we employ basic lean knowledge and principles at the start, we can have a facility that not only is lean, but also continues to seek out methods to become even leaner.