Level Production for Job Shops
Stop expediting by controlling release (not by working harder).
Short version (read this first)
If your shop feels slammed but shipments don’t rise, the issue is usually too much work released too early. That creates high WIP, priority fights, and expediting that multiplies late jobs.
The fix is workload control:
- Limit release so the floor only has what it can finish and ship.
- Use FIFO (first-in, first-out) to keep sequence stable instead of constantly reshuffling priorities.
- Near capacity, release based on what the governing workcenter can truly complete—not based on “keeping everyone busy.”
- If your bottleneck shifts with mix, level the mix (don’t batch all heavy-weld jobs together).
A simple weekly rule: Don’t celebrate “started.” Measure what finished and shipped.
A simple daily rule: Track hours scheduled vs hours completed at the governing step. If the governing step isn’t stable, the whole schedule is a guess.
Next step checklist (5 minutes):
- What shipped this week (finished) vs what’s still sitting as WIP?
- Where do jobs pile up right before they can’t move? (likely governing step)
- Freeze a basic FIFO lane for that step (stop reshuffling).
- Release only what supports shipping soon (not everything you can start).
- Review hours scheduled vs completed daily and adjust release.
Extra detailed version (examples + how-to)
This section is intentionally long for shop owners who want the “why” and the “how.”
What level production really means in a job shop
In a high-mix / low-volume shop, you can’t make every day identical. But you can control how much work enters the system and keep the sequence stable.
- You keep a steady release rate (not a steady start rate).
- You avoid flooding the floor with more WIP than the shop can finish.
- You keep the governing step fed and stable so shipments become predictable.
This isn’t an assembly-line schedule. It’s how you prevent the feast-or-famine cycle that ruins lead times and creates expediting.
Why expediting gets worse the harder you try
Expediting feels productive because it creates motion. But it usually causes constant priority changes, more setups and changeovers, more partial completions, and more “searching work.”
The loop looks like: release too early → WIP grows → lead times grow → due dates slip → expedites rise → the plan changes more often → shipments get less stable.
The shop is governed by one limiting step most days
Most shops have one step that decides what ships: a machine group, a cell, a skill constraint, or a non-production constraint (engineering release, quoting bandwidth, material availability).
- Where do jobs pile up right before they can’t move?
- Which department, when behind, causes everything else to slip?
Note: sometimes the limiting factor is demand (a lack of new orders). That still matters—leveling requires stable inputs upstream, too.
FIFO is good—but FIFO alone is not enough
FIFO stabilizes sequence, but it fails if the floor is drowning in WIP. You need both: FIFO plus release control. FIFO is lane discipline. Release control is the on-ramp meter.
Near capacity: release to governing capacity (not to keep everyone busy)
When a shop is near capacity, the most common mistake is trying to keep every upstream department fully busy. That increases queues and lead time. Instead, set release rules based on the governing step so it stays steadily loaded without drowning everything else.
Example: why more release can reduce output
If the governing step can reliably complete 40 hours/week:
- Controlled release keeps queues reasonable and output stable.
- Flood release increases priority churn and setup churn and can reduce governing output below 40.
Flooding creates more motion but less shipping.
High-mix reality: when the bottleneck moves
If the limiting step shifts by product mix, don’t try to guess perfectly. Level the mix:
- Don’t release all “heavy weld” jobs together.
- Mix job types across the week so the governing step stays stable.
- Use a weekly capacity map by workcenter to avoid predictable overload waves.
The daily signal: hours scheduled vs hours completed
Track hours scheduled vs hours completed at the governing step. This gives early risk warnings, supports safe/caution/critical intake decisions, and enables earlier customer communication—before a due date is already broken.
What to do when demand exceeds capacity
Options include adding hours, adding capability, reducing interruptions, improving changeover discipline, or adjusting price/lead time to control intake. The foundation remains release control plus stable sequence.
Job-shop implementation plan
- Measure throughput: What was truly finished and shipped this week? What’s still sitting as WIP?
- Identify the governing step: Where do jobs pile up right before they can’t move?
- Create a simple FIFO lane: Stop constant reshuffling; make next work visible.
- Control release: Release work to support shipping soon; avoid pushing everything just to start it.
- Track the daily signal: Hours scheduled vs hours completed; adjust release; remove interruptions.
- Level the mix: Smooth the week; avoid batching overload.
- Repeat: When the limiter shifts, reassess and adjust.
FAQ
What is level production in a job shop?
It’s keeping a steady release rate and stable sequence so WIP stays bounded and shipping becomes predictable—even in high-mix work.
Why does more WIP increase lead time?
More WIP means longer queues, more searching/staging, and more priority changes. Jobs spend more time waiting than moving.
What’s the difference between FIFO and scheduling?
FIFO controls the sequence of what gets worked next. Scheduling decides how much work enters and when. FIFO helps, but release control prevents overload.
How do I identify the governing workcenter?
Look for where work piles up before it can’t move, and which department’s delays most often dictate what ships.
What if the bottleneck changes every week?
Level the mix across the week so you avoid predictable overload waves. Track which step governs shipments most days and adjust release accordingly.
How do I control release without starving departments?
Aim for a steady release rate tied to what the governing step can finish. Keep a visible FIFO lane so teams always know what to work next without flooding the floor.
What should I track daily to stabilize delivery?
Hours scheduled vs hours completed at the governing step. If that daily signal is stable, the rest of the schedule becomes more trustworthy.
How does workload control improve quoting and lead times?
Stable queues and predictable completion rates make promise dates less “wishful thinking.” Over time, estimate vs actual improves because you can see where time is really going.