Try it while you read
Open the free LPA Schedule Generator tool and click Load sample: it reproduces the case study below.
Theory: why the schedule matters as much as the checklist
A layered process audit only works if it really happens, at every level, at every station. Without a schedule the same manager audits the same easy station every time and the difficult ones are never seen. The schedule fixes three things: who audits (the layer and the person), where (a rotation through all stations) and when (the frequency of the layer).
Frequency per layer
| Layer | Typical auditor | Typical frequency |
|---|---|---|
| 1 | Team leader | Every shift or daily |
| 2 | Supervisor, quality engineer | Weekly |
| 3 | Department / production manager | Monthly |
| 4 | Plant manager | Quarterly or monthly |
Coverage and workload
The coverage matrix shows how often each layer visits each station in the plan. A layer that audits monthly cannot visit six stations in four weeks, so either the plan must be longer or the station list for that layer shorter. The workload per auditor (audits × minutes per week) shows whether the plan is realistic before it is published.
Key point
Step by step
- Stations: one per line in the LPA schedule generator, in process order.
- Layers: name, auditors (several names rotate) and frequency: per shift, daily, weekly, monthly or quarterly.
- Plan: start date, number of weeks, workdays (5 or 6), shifts per day and minutes per audit.
- Check the coverage matrix and the gap list; lengthen the plan or reduce the stations of a layer where needed.
- Publish the calendar board as a PDF, one sheet per week, on the shop floor.
- Audit with the LPA checklist and record every NOK with a reaction.
Case study: shaft line with six stations
The Load sample plan covers six stations (sawing, two CNC turning stations, heat treatment, grinding, final inspection), four weeks, five workdays, two shifts, 15 minutes per audit.
| Layer | Frequency | Audits in 4 weeks | Hours per week |
|---|---|---|---|
| 1 Team leader (2 auditors) | Every shift | 40 | 2.5 |
| 2 Supervisor, quality engineer | Weekly | 8 | 0.5 |
| 3 Production manager | Monthly | 2 | 0.13 |
| 4 Plant manager | Quarterly | 1 | 0.06 |
| Total | 51 | ||
Layers 1 and 2 visit every station within four weeks. The gap list shows that layer 3 misses four stations and layer 4 five, which is expected with monthly and quarterly audits in a four-week plan. The team extends the plan to 26 weeks for layers 3 and 4, so the production manager sees every station twice a year and the plant manager the two stations with special characteristics (heat treatment and grinding) first.
Result
Common mistakes
- A schedule without names: “supervisor” as auditor means nobody feels responsible.
- Managers always auditing the station next to their office.
- More audits than the auditors can do, so the completion rate drops and the system loses credibility.
- Moving missed audits silently to the next week.
- The same checklist for years: change questions when problems are solved and new risks appear.
Background on the method: layered process audit guide and LPA vs process audit.
Frequently asked questions
How many layers does an LPA need?
Usually three or four: team leader, supervisor or quality engineer, department manager and plant manager. The point is that every management level regularly sees the shop floor.
How often should each layer audit?
A common rhythm following AIAG CQI-8 is every shift or every day for layer 1, weekly for layer 2, monthly for layer 3 and quarterly for the plant manager. Customer-specific requirements may set other minimums.
What if an audit is missed?
Record it as missed, not as done later without a note. The completion rate per layer is one of the key LPA metrics and is often asked for in customer audits.