# Why is there a gap in my jobs operations?

I am looking at the Job Scheduling Board. I can see a large gap of over a month between two operations. Op 50 is a finite resource op, but op 60 is an infinite resource op. Op 50 uses ID 25, and Op 60 uses ID 5BP00062.

Can you tell what is going on from my images?
How can I figure out what is causing this gap in my operations?

Can you expand this line into as many levels and post a new image:

How about a picture of the resource scheduling board for op 50 resource? Could that resource not have another window to schedule on closer to op 60?

What’s your scheduling set for the operations. Those on the left compared to those on the right:

All of our ops are set to Finish-To-Start.

Do you have these set:

It looks like the jobs are not being scheduled infinitely to this resource. That was it! Someone set this resource to finite! Dang someone!
I think the best took for finding this was the resource scheduling board. But I had to use the multi resource and job scheduling boards to track it down.
Thanks for the help everyone!
Nate

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Theres yer problem right there!

We really should be moving towards more finite resources, and this is one of them. So we may have been thinking ahead. All the rest of my resource groups are infinite. And now I am going to check that statement!

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Gaps are IN right now. The scheduling is just trying to achieve that thigh gap.

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I have seen this before in cases where finite and infinite operations are next to each other… AND this also depends on whether you do FORWARD or BACKWARD scheduling.

BUT we have an answer… if you are using backward scheduling, but do not allow scheduling into the past, OR if you are using forward scheduling, you will run into this same problem.

1. system schedules backwards first (if using backward scheduing)… it runs into today
2. System will RESCHEDULE using TODAY as the start point, and FORWARD schedule. While rescheduling it runs into a constraint, and a big gap is put into the schedule.

BUT if you choose a Scheduing Priority Code that has the “Minimize WIP” flag set, then the system will do one additional reschedule after the completion date is done… in other words, it:

1. backward schedules
2. Forward schedules, setting the completion date
3. Backward schedules using the Completion date as the target. This will compress the schedule.

Create or change one of your current Priority Codes to have the Minimize WIP flag set to true. If you set this on for the DEFAULT scheduling code, then it would be used by all new MRP jobs:

Here is where the scheduling priority code is used in the JOB.

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We do not allow scheduling in the past.
We mostly backward schedule from the due date. But sometimes we choose specific jobs to forward schedule.
Our ops are set to Finish to Start.
Finite horizon 365 days.
We don’t have MRP.

I have never used the minimize wip flag before. I will experiment and see if we need to use that.

if you backward schedule, and you do not allow scheduling in the past, then the system WILL by default automatically do forward scheduling if it runs into the past on any job. By setting that minimize wip flag, you will see that it should resolve itself. You can simply check the box, and reschedule a job and see the results.

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Is there a way to achieve this during the MRP run, or does it require running Global scheduling after MRP to utilize the Minimize WIP?

I am trying to understand WIP in the schedule. My understanding of WIP is from an finance side. We have all these parts out on the floor that are at various stages of completion. Until they are complete their WIP value increases until they reach the last op, and they attain their full shippable value. At which point they no longer have any WIP value.

How does WIP fit into scheduling from my (admittedly limited) financial understanding?

If I’m understanding you correctly, then you’re trying to figure out the correlation of WIP VALUE to the Scheduling engine… and there is no such correlation. Scheduling has absolutely nothing to do with value, its only concern is making parts with the most efficient use of machine/people resources in the time allotted (Ship By Date).

Is that what you’re asking?

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Sort of. So How does minimize WIP affect my schedule? (See @timshuwy’s post above).

I believe when Tim said, “it compresses the schedule” that the value remains in WIP for a shorter period of time, hence minimizing it.

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Correct @Mark_Wonsil… it is the quantity/time meaning of WIP, not the value meaning.