Which Job Should Run Next? Setting Priorities in a Small Shop

The next job is usually one that is ready to run and has little room left before its promised ship date. The tricky part is knowing what ‘little room’ means: a Friday shipment with two outside operations may need attention before a Thursday shipment that only needs packing.

A workable priority list brings together three things: what can run, how much time remains, and which resource is limiting the shop's output.

Separate ready work from blocked work

Two short lists help: ready to run and waiting on something. The ship date, next operation and blocker are enough to start the discussion. A whiteboard or shared sheet can work if someone keeps it current.

Ready means the next operation has what it needs: usable material, current instructions, tooling and the right person or machine. The following operation matters too, especially when releasing a batch would only create another pile of waiting work.

A late job with missing material still needs urgent attention. Its blocker needs an owner and a next check time; it cannot yet be the operator's next runnable job. For example: “Waiting for inserts; purchasing confirms delivery by 10 a.m.”

When several jobs use the same components, those jobs are competing for the stock. The priority decision includes which job gets it, not just which row appears first.

Look beyond the earliest ship date

An earliest-due-date list is useful, but it does not show how much work remains. A job shipping Friday might need heat treatment and inspection before packing. Another shipping Thursday might only need a short assembly operation.

Working backward from the promised ship date exposes that difference. Setup, outside services, inspection, packing and likely queues all take time beyond the machine run itself. A customer delivery date also needs an allowance for transit.

A rough latest-start time can show which jobs need attention without minute-by-minute scheduling. A practical note might be: “Must reach coating Tuesday to ship Friday.” Confirm that timing with the supplier rather than assuming their quoted lead time starts when your parts leave the shop.

Check the constrained operation

The most useful place to check capacity is often the resource whose limited time is holding up shipments: welding, inspection or the one person who can set up a particular machine. A good sequence keeps suitable work ready for that resource without flooding later steps with more than they can handle.

The Lean Enterprise Institute's guidance for make-to-order work describes regulating work release around bottleneck capacity, rather than simply pushing whole customer orders onto the floor.

Here is a simplified example for one shared machine:

If the machine has 8 productive hours available today, A and B use all eight. With only the constraints shown, either sequence could meet their timing needs. A specific pickup cutoff or a setup advantage could break the tie. Job C needs someone chasing the shortage, but putting it first on the machine's list does not make it runnable.

Those eight hours must reflect the time actually available for these jobs, after known breaks, maintenance and other commitments. If the estimates are uncertain, leave room for that uncertainty instead of treating the full day as guaranteed capacity.

Give rush orders a clear tradeoff

Suppose a new, ready job needs two hours on that same machine today. The total becomes 10 hours against 8 available. Moving it to the top changes which job waits; it does not create capacity.

The question becomes: which existing job moves, and can it still ship on time? A partial shipment, suitable alternate resource, extra capacity or a negotiated date may be an option. Each needs checking before the rush date is promised.

One person should approve changes to the agreed sequence. In a small shop, that may be the owner. Operators should be able to flag a bad sequence or suggest a setup saving, but the changed priority needs to reach everyone affected.

Grouping similar setups can help when delivery commitments allow it. It should not quietly move a critical job behind a week's worth of convenient work.

Keep the daily review short

A short start-of-shift conversation can focus on what changed:

• What finished, and what is actually ready now?
• Which jobs are at risk of missing their next required step or ship date?
• What is blocking the constrained resource?
• Has an approved change displaced another job?

The outcome is an updated list and a named owner for each unresolved blocker. Once the team knows the sequence, another review is useful when something material changes, rather than every time someone asks about a job.

Reliable estimates matter. In a NIST MEP case study, Stainless Works corrected routing information and identified welding as a bottleneck as part of improving its ERP scheduling. The useful lesson is to check the information behind the plan, not just rearrange its rows.

Using this approach in PAX

PAX work orders include a due date and a priority from 1 to 10, with lower numbers treated as higher priority. The work-order list shows those fields alongside status and completed quantity. Consistent meanings for the numbers make a priority change useful to the people reading the list. See the work-order list documentation.

When creating a work order, PAX also compares direct BOM component requirements with stock on hand. That check is advisory: it does not reserve material or establish that people, machines and every later operation are available. See the material-check details.