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Insights on production scheduling, lean manufacturing, and manufacturing software from 35+ years of industry experience.
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Featured Guides
Plan on Lead Time vs Require on Hand: the Material Availability Choice
A product's Material Availability setting decides whether a job without covering supply is planned on an assumption or reported as a shortage. Here is what each choice does to the plan.
Why a Missing Tool Stops the Job Instead of Scheduling Anyway
A step whose tool is inactive, unknown, or at zero quantity fails the run immediately and names the tool. Why that refusal is a feature, not a limitation.
Why a Tool Is Held for Setup and Run Alike
An operator can tend two machines at once. A fixture cannot be half mounted. Why tools book at the full rate for every hour, with no attention fraction and no escape.
One Fixture, Two Mills: How the Schedule Resolves the Clash
Two jobs on two free machines that cannot both run. A worked example of how a shared fixture splits one of them across two days without changing its hours.
The Tool Constraint: The Third Thing an Operation Needs
A tool constraint models the fixture, mold, or gauge shared across every machine, so the schedule sees the one clash a normal Gantt cannot show you.
What Changes When You Own a Second Fixture
Tool quantity is units you own, not machines it fits. What raising it from one to two really buys, and why inflating it is the most damaging entry in the model.
How a Constraint Schedule Subordinates Every Other Step
When a job is anchored to a constraint, the engine ranks every other step below it on a descending priority ladder. How the ladder works and why upstream steps drop fastest.
How to Keep a Slow Machine Out of a Machine Pool
There is no automatic efficiency screen on a pool. Four real controls decide which machines a step can use: the member list, the Active flag, the per-member factor, and the selection strategy.
How a Step-Level One-Per-Day Rule Overrides the Machine
One job per day can be set on the machine or on the individual routing step. How the step-level rule wins, when to use it, and what it does to capacity on a shared machine.
How a Synchronized Group Buffer Differs From Queue Time
A parallel group can carry its own buffer after the machines finish together. How that padding differs from queue time and transfer delay, and which one to use when.
The Smallest Slice of Capacity a Scheduler Will Use
Why a finite capacity engine refuses to book six-minute fragments of a shift, how the minimum allocation unit prevents rounding drift, and what it means for short operations.
When an Operation Must Fit Inside One Shift
Most operations spill across shifts until their hours are placed. Some cannot. How the cross-shift and partial-shift rules work, what they cost, and when to turn them off.