Tracking WIP when jobs move between operations

The trap: tracking every operation

The instinct is to log every operation on every job — start time, stop time, quantity moved. It produces a beautiful data model and it fails in most small shops for one reason: the entry burden falls on people who are already busy, so entries arrive late, in batches, or not at all. Late data is worse than coarse data, because it looks precise while being wrong.

Start coarser than feels right. One current-stage field per job, updated once a day, gives you a WIP picture accurate to within a day. That is enough to run a shop.

What WIP actually needs to answer

Three questions. How many jobs are in process and where are they sitting. How many hours of work are still in the building. How much money is tied up in unfinished work. Every one of those is answerable from a job list with a current stage and remaining hours.

• Job count by stage — where the pile is
• Remaining hours by stage — how big the pile is in work, not in units
• Value in process — remaining hours costed, plus material already issued
• Age in stage — the field that finds the job quietly stuck behind a fixture

Move the stage, keep the history

When a job moves from turning to grinding, change the current-stage field and stamp the date it entered the new stage. Two fields, one edit. Age in stage falls out of the date, and the stage change itself is the only event you need to capture.

If you later want operation-level history, log completions to a separate list rather than adding columns to the job row. The job row stays one row per job, which is what keeps the summaries simple and the file fast.

Reconcile against the floor, monthly

Once a month, walk the shop with the WIP summary and check that the jobs the sheet says are at weld are in fact at weld. You will find two or three wrong, fix them, and learn where the update routine is breaking. Skip this and the summary drifts until nobody quotes it in a meeting.

Reconciliation is also how you catch the job that shipped without being closed. Those are the rows that quietly inflate WIP hours and make the number useless to the owner.

Where a tracker helps

The Production Control System keeps stage, remaining hours, and value in process on the same job list that drives the schedule and the at-risk flags, so WIP is a by-product of the daily update rather than a second system to maintain.