Gemba Data Collection: Checklist for Mapping the Current State
The quality of a value stream map is decided on the shop floor. Numbers from the ERP system describe the plan, not reality. This checklist shows what to collect at each process, how to measure, and how the data gets into the map.
Preparation
- Define the product family: products that go through the same process steps on the same equipment (product family matrix).
- Get customer data: demand per day or month, delivery frequency, the customer's container or batch sizes.
- Clarify available working time: shifts, breaks, planned downtime; from these, the net available working time per day.
- Team and timing: two people, a normal production day, starting at shipping.
What to record at each process
Walk the flow backward from shipping. At each process, fill in the data box:
- Cycle time: the time between two finished parts, at least five readings, median or mean. With several operators, take the time per part at the process exit.
- Changeover time: from the last good part of the old product to the first good part of the new one.
- Uptime: the share of working time in which the process is not stopped by breakdowns. Record changeovers separately through changeover time and batch size.
- Scrap and rework rate in percent, batch size, number of operators and machines, shifts, EPEI.
- With several products: cycle time and changeover time per product.
Inventory and information flow
Count inventory on the day you walk the floor: before the process, after the process, in buffer storage and in transit. Count pieces, or containers × quantity per container, not the stock level in the system.
For the information flow, ask at each process: how do you know what to make next? The answers (weekly schedule, verbal instruction, kanban, "go see") are the arrows at the top of the map.
Measuring with your phone
With the mobile data capture in the app you time cycle times right at the line: start, tap "Part done" for each finished part, stop. The mean or median goes into the data box as cycle time. Changeover time, uptime, scrap rate and operators go into large input fields. Without a connection, the values are buffered and sent later. The link is available in every live session, also as a QR code.
Common mistakes
- Using standard times from the routing instead of measured cycle times.
- Taking only one reading instead of several; breakdowns distort the value.
- Copying inventory from the system instead of counting it.
- Leaving out the information flow: without it, the map cannot explain why inventory builds up.
Practice in the editor
Start with the blank current state template and enter the processes of your line with measured cycle times.
Open the template in the editor Start blankFrequently asked questions
How many cycle time readings do I need?
At least five, and ten for processes with a lot of variation. The median is more robust against outliers than the mean; you can choose either in the mobile data capture.
Cycle time or work content?
Cycle time measures the interval between two finished parts at the process exit. Work content is the pure working time on the part; with several operators it is longer than the cycle time.