Every tenth part, a column of numbers nobody reads
The inspection plan says to measure the bore, the overall length and the thread every tenth part. The operator does it, conscientiously, and writes the readings on a sheet clipped to the machine. By the end of the shift the sheet is smudged with coolant and the handwriting is hard to read.
The sheet goes in the job folder. Nobody looks at it again unless a customer complains. Then someone finds that the bore had been creeping up for three hours before it went out of tolerance, and the readings were there all along.
Why paper records do not protect you
Paper check sheets satisfy the requirement to record, but they are not built to be read. Numbers in a column do not show a trend. They cannot tell the operator that the last three readings are all near the top of the tolerance. And they cannot be searched later.
- Readings are written, so they cannot be charted or compared.
- Tool wear and thermal drift show up only when a part fails.
- Missed checks are not obvious until the sheet is reviewed.
- Digital gauges are used, but their readings are still copied by hand.
- The inspection plan and the check sheet are maintained separately and drift apart.
What it costs you
Batches that were fine in the morning and out of tolerance by the afternoon, found at final inspection or, worse, by the customer. Sorting and scrapping a whole batch because you cannot prove which parts were made before the drift started. Hours of inspector time copying readings for customers who ask for measurement data. And no evidence to help the setter decide when to change a tool.
The digital check sheets we build
- Each job's inspection plan lists the characteristics to check, how often, which gauge to use and the tolerance. It is the same plan the inspector uses, so there is only one version.
- At the machine, a tablet shows the check sheet for the job when the traveller is scanned. It tells the operator when the next check is due.
- Readings are typed in or taken directly from digital gauges with a USB or wireless connection, so they are not copied by hand.
- Each reading is shown against its tolerance as a simple bar, and a small chart per dimension shows the run so far.
- Simple rules warn the operator and the setter when readings trend towards a limit or several fall on the same side, before a part is out.
- Missed checks are flagged on the job, and the supervisor sees them on a daily list.
- At the end of the job, the data is stored against the job, part and revision, and can be exported for a customer's capability study or report.
| On paper | On the check sheet we build |
|---|---|
| Numbers in a column | Each reading placed in its tolerance band |
| Drift noticed at failure | Warning as readings trend towards a limit |
| Missed checks unknown | Missed checks flagged the same shift |
| Retyped for customer reports | Exported from stored readings |
| Plan and sheet differ | One inspection plan feeds both |
On the shop floor
Operators get a clear signal to call the setter before a part goes out of tolerance, instead of a column of numbers that only means something to the inspector. Setters can see how quickly a tool wears on a given material and change inserts at a sensible point. When a customer asks for measurement data on a batch, it is an export, not a typing job.
Quality meetings also change. Instead of discussing the scrap that happened, you can look at which dimensions on which parts sit close to their limits, and fix the process or the fixture before they cause trouble.
Are your check sheets doing their job?
- Check sheets are on paper at the machine.
- You have scrapped a batch that drifted over a shift.
- Digital gauge readings are copied by hand.
- Customers ask for measurement data you have to retype.
- Nobody reviews check sheets unless there is a complaint.