A Pieces-Based Work Center Scheduled in Hours: Why, and the Fix

A pieces-based work center only schedules by output when the routing step it runs actually carries a pieces requirement, so a work center set to Pieces capacity that still schedules in run hours is almost always a step missing its pieces-required value. EDGEBIC by User Solutions needs the capacity type on the work center and the pieces requirement on the step together before it will derive a duration from the output rate.

This post sits in the EDGEBIC troubleshooting guide and is the practical companion to pieces-based versus hours-based capacity and the general idea of finite versus infinite capacity scheduling.

What You Are Seeing

You configured a work center to measure capacity in pieces (the molding cell, the stamping press, the fill line), set a pieces-per-hour rate, and expected the schedule to size jobs by how many parts each operation produces. Instead the job bars come out sized off the routing's run hours, exactly as they did before you changed the capacity type. The pieces rate looks ignored, and the two settings appear to disagree.

Why It Happens

Pieces scheduling is a two-part contract, and both parts have to be present.

• The work center holds the capacity type and the rate. Setting a work center to Pieces (or Both) tells the scheduler this resource measures its own output, and the pieces-per-hour rate is how fast it produces. That is the supply side.
• The routing step holds the demand. The scheduler turns output into time by dividing the step's pieces required by the work center's effective pieces per hour. That pieces-required value lives on the routing step, not on the work center.
• No pieces required means no pieces duration. If the step carries only run hours and no pieces requirement, there is nothing for the rate to divide, so the scheduler uses the run hours on the step. The capacity type is set, but the step never gave it a number to work with.

The effective rate matters too. Effective pieces per hour is the base pieces-per-hour rate times the efficiency factor, so a rate of zero (or a step with no requirement) both send the calculation down the hours path. If you change that factor and the line barely moves, an efficiency factor change that barely moved a pieces line covers how to find the number the step is really consulting.

How to Fix It

Complete the contract: put a pieces requirement on the step and confirm the rate on the work center.

1. Confirm the work center's capacity type. It should be Pieces (output only) or Both (whichever of pieces and hours is limiting). How to schedule a work center in pieces instead of hours walks the setting.
2. Confirm a non-zero pieces-per-hour rate. A rate of zero cannot produce a duration, so the scheduler falls to hours.
3. Set the pieces required on the routing step. This is the count the operation must produce. Without it, the scheduler has no output demand to size against.
4. Re-run scheduling and check one step. The duration should now be pieces required divided by effective pieces per hour. Six hundred pieces at an effective one hundred per hour is six hours. If it still shows the old run hours, the step is still missing its pieces value.

How to Prevent It

• Treat the pair as one setup. When you make a work center pieces-based, plan to set the pieces required on every routing step that runs through it. The capacity type alone changes nothing about how a hours-only step is sized.
• Watch the Both capacity type. A work center set to Both schedules on whichever of pieces and hours is the limiting constraint, so a step with a pieces requirement and run hours can still land on the hours if the hours are longer. That is correct behavior, not a bug.
• Keep the rate honest. The effective pieces per hour is the base rate times the efficiency factor. A left-at-zero rate is the most common reason a pieces work center quietly schedules in hours.
• Spot-check a converted step. After switching a work center to pieces, open one job and confirm its duration equals pieces required divided by effective pieces per hour. That single check tells you both halves of the contract are in place.

If instead your hours and pieces numbers disagree on the floor, that conversion is covered in the concept side of pieces-based versus hours-based capacity, and for the broader mechanics of resource sizing see what is production scheduling. If the resource is a reactor, oven, or coating line that should flow rather than move countable parts, a continuous-process work center scheduling in batches covers the flag that picks the overlap model.