An Operation Moved and the Machine Was Free: Finding the Hidden Cause

When an operation moves and every machine shows free hours, the constraint that bound it was not a machine, and a shared tool is the candidate the Gantt cannot draw for you. EDGEBIC by User Solutions puts a marker on skill-required operations and does not put one on tool-required operations, so a fixture clash is the one cause that leaves no visual trace. Two minutes of checking rules it in or out before you spend an hour on calendars.

This is the tooling-specific version of a symptom covered more broadly in the EDGEBIC troubleshooting guide.

First: Check the Step's Required Tool

Start here, because it is the cheapest possible test and it either eliminates a whole family of causes or hands you the answer.

Open the routing step in the BOR tab and look at Required tool: in the Basic Information section. In the BOR Designer, the same setting is on the node's properties panel as Required Tool.

• It reads (none). Tooling is ruled out for this step entirely. Move on to skills, upstream steps, and calendars.
• It names a tool. Keep reading. You are probably two minutes from the answer.

The reason this ordering pays is that the tooling symptom is indistinguishable from a machine-capacity symptom right up until you look, and the machine investigation is much slower.

Cause 1: Another Job Took the Pool

The headline case, and by a wide margin the most common.

A tool has a pool of hours for each day and shift: the quantity multiplied by that window's working hours. Every allocated machine-hour books one hour from it, and that pool is shared by every work center running the same tool. When it runs out, the next operation is simply not offered the window, and it slides.

How to tell: find the other routing steps that require the same tool, and look at what is scheduled against them in the window your job wanted. If a job on a different machine is sitting there, it took the hours.

The confusing part is that the competing job may be somewhere you would never look. A fixture shared between a mill cell and an inspection bench means the job that moved your job could be in another department entirely. Nothing links the two bars on screen.

Fix: this is not a defect, it is the constraint working. The options are to raise the quantity if you own another unit, to resequence so the more urgent job takes the fixture first, or to accept the date. What a second unit really buys is measurable: see what changes when you own a second fixture.

Cause 2: The Tool Is Away

If the operation did not just slide a few hours but jumped clean over several days, check the tool's downtime.

Open the Daily Hours tab, the Tools inner tab, select the tool, and read its downtime grid. On every date inside a range the pool is zero regardless of quantity, so operations requiring the tool skip those days entirely.

How to tell: the gap in the schedule matches a downtime range exactly, and work resumes on the first day after it.

The classic off-by-one: both dates are inclusive. If work resumed one day later than you expected, the end date is almost certainly one day too far out. It should be the last day the tool is genuinely absent, not the day it comes back. See how to record tool downtime.

Cause 3: A Step You Forgot Requires It

A quieter version of cause 1. If a tool is required on more steps than you remember, its pool is under more pressure than you expect, and the job that moved may be competing with an operation nobody thinks of as a fixture job.

How to tell: attempt to delete the tool. The delete is refused and the message counts the routing steps that still require it. If that number is larger than your mental model, that is the finding, and nothing was changed by the attempt.

Fix: decide whether each of those steps genuinely holds the tool. A step that carries the requirement but only needs the fixture for part of its duration books the whole step's hours, which overstates contention. Splitting it into a short tool-bearing step and a longer one without is the honest fix, and it frees real pool hours.

Cause 4: Surviving Work Re-Reserved Its Hours

On a reschedule, work that survives the run re-reserves its tool hours before any new work is placed. That is correct and necessary, but it can look surprising if you were expecting a rescheduled job to find the pool empty.

How to tell: the job that took the pool is one that was already scheduled and not yet started, and it did not move in this run.

Fix: none needed. Without this behavior a reschedule would plan new work straight over hours the existing plan is still holding, which is the most insidious way a tooling model can quietly stop being true. Rescheduling behavior generally is in how to reschedule safely.

Confirming It with the Run Log

If you want proof rather than a strong inference, the run's diagnostic log carries tooling-tagged lines that record exactly what happened: every booking made, with the running pool value, and every window that was skipped because the pool was empty or the tool was in downtime.

That log is the only place tool consumption is written down. There is no persisted record of which fixture went where, no tool lane on the Gantt, and no report that answers "where is FIX-EM47 on Thursday." Reading the routing steps and the log is the method.

Ruling Tooling Out Fast

If the step's required tool is (none), work down the usual list instead:

1. A required skill. Skill-required operations do carry a marker on the Gantt and a column in the Job View, so this one is visible. See how EDGEBIC books operator hours.
2. An upstream step. The operation cannot start before its predecessor ends, and the predecessor may have moved for its own reasons.
3. Calendars and capacity on the machine. The zero-capacity checklist walks that chain in order of likelihood.

Stop It Coming Back

Three habits retire most of this page:

1. Record which machines a tool fits in its notes field. EDGEBIC does not model tool-to-machine compatibility, so the notes are the only place a planner can learn where a fixture can turn up. That is what turns "why did this move" into "of course, the other mill."
2. Keep the requirement on exactly the steps that physically hold the tool. Too few understates contention; too many manufactures slides that should not exist.
3. Enter calibration and repair windows the moment they are booked, and reschedule. A known absence that was never entered will keep producing surprises until it does.