If you’re new to layered process audits, it’s critical to make sure everyone on your team is on the same page with basic terms. Here we provide a guide of 16 essential terms to know when launching your LPA program and getting your team up to speed. Don’t forget to directly download your own copy of this guide to keep as a reference for yourself and your team.
- Why is final assembly downtime higher than our target? Because operators must repeatedly adjust Machine A.
- Why do operators have to repeatedly adjust Machine A? Because the machine has constant alignment problems.
- Why does Machine A have constant alignment problems? Because its seals are worn.
- Why are the machine’s seals worn down? Because they aren’t being replaced at the proper frequency.
- Why aren’t they being replaced at the proper frequency? Because seal replacement wasn’t listed on the needs assessment as part of preventive maintenance.
5S is a Lean Manufacturing tool focused on making a workplace the the American Society for Quality calls “clean, uncluttered, safe and well organized to help reduce waste and optimize productivity.” Many organizations base LPA questions on the pillars of 5S, with the original Japanese and translated concept as follows:
- Seiri (sort)
- Seiton (straighten)
- Seiso (shine)
- Seiketsu (standardize)
- Shitsuke (sustain)
8D refers to 8 Disciplines, a problem-solving approach for systematically identifying and correcting the root causes of problems. The steps of the 8D method include:
· D0: Plan
· D1: Form a team
· D2: Define and describe the problem
· D3: Take interim containment actions
· D4: Analyze the root cause
· D5: Formulate and select corrective actions
· D6: Implement and validate corrective actions
· D7: Identify and implement preventive actions
· D8: Recognize the team and individuals
A layered process auditor can be anyone in the organization, drawing from departments that include (but are not limited to):
- Human resources
Containment refers to steps taken to limit the impact and extent of nonconformances. For example, if a failed LPA question reveals a batch of potentially defective product, containment would require separated the impacted products for review to ensure they didn’t get shipped to the customer.
Corrective action is a process for nonconformances that require a full investigation and multi-step action plan to fix. Steps of the corrective action process include:
· Describing the problem and flagging it for review
· Conducting a root cause analysis using tools such as the 5 Whys or 8D
· Creating an action plan with deadlines and responsible parties clearly described (more elegant)
· Management review to ensure timeliness of completion by discussing any roadblocks
· Follow-up to ensure you’re holding the gains, such as by adding a new LPA question to check in on the process
A fishbone diagram is a visual problem-solving approach that allows teams to sort potential root causes (and sub-causes) into different categories.
A Gemba walk is a Lean tool used to get managers on the plant floor or gemba, Japanese for “the real place,” or where the work is done. Companies already conducting Gemba walks are often ideal candidates to implement LPAs as the next step in improving quality culture.
A layer refers to an auditor’s level within the organization and, in turn, the person’s audit frequency. A typical LPA system has three layers.
Layered Process Audit
Layered process audits examine inputs such as methods and materials to identify sources of variation upstream from the point of manufacture. This is in contrast with product inspections, which focus on examining finished products to find defects.
A leading indicator measures input or conditions that predict changes in lagging indicators, which are typically outputs or results you’re targeting. For example, a dip in audit completion rate may precede a spike in customer complaints. In this case, audit completion rate is the leading indicator, while complaints are the lagging indicator. Tracking leading indicators allows you to step in before problems spread.
Within the context of LPAs, mitigation typically refers to minor on-the-spot fixes for nonconformances that do not require a root cause analysis or larger corrective action process.
A Pareto chart is a combined bar chart with line graph showing the frequency and relative significance of various problems. Pareto charts are a common LPA reporting tool to show categories of failed questions, helping companies quickly identify critical areas of focus.
Process failure mode and effects analysis (PFMEA) is a quality tool for analyzing the ways a process could potentially fail and identifying controls to reduce risk. PFMEAs are a primary source of LPA questions.
A reaction plan outlines what auditors should do in the event of a failed question. Each LPA question should have a reaction plan, which could include steps such as:
- Notifying a supervisor
- Fixing or containing problems during the audit, as appropriate
- Initiating the full corrective action process
Verification refers to the fact that LPA questions use yes or no format to quickly identify compliance with process standards, as opposed to taking measurements of finished products.
LPAs are a powerful tool for reducing quality problems, particularly with an automated LPA platform to keep audits on track and monitor real-time data. Before you start, however, it’s critical to have an understanding of the basics—including basic terms—so you know everyone is on the same page.