Roughly 7 in 10 manufacturers have implemented Lean manufacturing principles in their organizations, with 5S, Six Sigma and Kaizen representing the most popular strategies today.

One tool that supports these specific approaches and Lean manufacturing principles more generally is a layered process audit (LPA) program. LPAs draw auditors from all management layers and departments to verify mission-critical processes on a daily basis.

Let’s examine how LPAs align with Lean manufacturing principles, providing a structured approach to unlock the biggest benefits of this popular quality methodology.

The 3Ms of Waste in Lean Manufacturing

At the heart of the Lean methodology is a focus on reducing three broad categories of waste called the 3Ms:

• Muda: This term refers to activities that add no value, which according to the Lean Enterprise Research Centre, represents 60% of activities in manufacturing.
• Mura: Translating to “unevenness” in Japanese, mura is caused by unleveled demand leading to unused capacity at some times and a mad rush at others.
• Muri: This word means “overburden” and represents all the ways companies over stress workers and processes.

Process audits help identify these types of inefficiency by providing daily observation and analysis of production processes. Auditors from across the plant also bring new viewpoints to improvement efforts, helping attack the 3Ms on a high level.

Addressing the 7 Wastes of Lean with Process Audits

Mura and muri are themselves drivers of muda, which can be broken down into the 7 wastes of Lean that many of us are familiar with:

• Transport
• Inventory
• Motion
• Waiting
• Overproduction
• Over-processing
• Defects

The types of questions covered by process audit checklists specifically address each of these seven types of muda. They’re especially good at catching and correcting process errors early, when they’re much less expensive to correct. In fact, automotive and aerospace companies have used LPAs to cut customer defects by more than half, also reducing internal PPM by 73%.

5S and Gemba Kaizen

Process Excellence Network defines Gemba Kaizen as “a Japanese concept of continuous improvement designed for enhancing processes and reducing waste.”

Gemba refers to where the work is done—the plant floor. Like Gemba walks, LPAs require direct observation of plant floor processes where value is created.

Kaizen focuses on improvements, specifically the 5S methodology to sort, set in order, scrub, standardize and sustain. Not only can LPAs incorporate specific 5S audit questions, they also support overarching goals of 5S and Kaizen more generally. A few examples:

• Discipline: LPAs require operators to audit processes every shift, while a plant manager and executives might participate weekly or monthly. Discipline in adhering to the audit process and schedule drives results.
• Process standardization: Process audits verify that operators execute tasks consistently according to defined work standards. Executing processes the same way every time is critical to quality, but it’s difficult with repetitive activities, which naturally lead to inattention and shortcuts.
• Problem-solving: LPAs create closed-loop processes for solving problems and sustaining the gains through repeat verification. Further discussion on this element and how LPAs and Lean problem-solving methods fit together follows below.

Process Audits and Lean Six Sigma Problem-Solving

Also known as the Deming or Shewhart cycle, the Plan-Do-Check-Act (PDCA) cycle is a common approach to problem-solving in Lean and other methodologies. An extension of the PDCA cycle is the statistically structured Six Sigma method called DMAIC (define, measure, analyze, identify and control), which is more effective when you have vast amounts of data to apply to the problem.

LPAs align with both of these cycles, helping companies solve problems and mitigate risk throughout the production process. How does LPA fit with these cyclical approaches?

• Plan (Define, Measure, Analyze): LPA findings help you identify areas of improvement and what you need to do to get there. For instance, LPA data like audit completion rates and number of non-conformances can act as leading indicators for reducing defects and costs.
• Do (Improve): LPAs help you execute change in a consistent, performance-based manner.
• Check (Control): Data from your LPAs are helpful for evaluating results of improvement efforts. Continuously adding and rotating questions helps check that you improvements are sustained.
• Act (Control): An effective process audit program includes procedures for addressing non-conformances. That may mean fixing an issue during the audit and recording the mitigation, or assigning the item for corrective action.

Experts will tell you that when Lean programs fail to deliver results, it’s often because of a lack of buy-in and understanding on an organizational level. It’s an area where LPAs provide a distinct advantage, because they make quality part of the daily routine for the entire organization. If you use an automated LPA platform, you can also instantly share results with the team, compared with the lack of visibility inherent to paper-based systems.

Increased visibility provides proof of the value of process audits, helping communicate wins to keep your team motivated and engaged. It gets to the core of what Lean is all about—hard data, continuous improvement and the synergy that comes from an engaged team.