Question

Definition of Queue Time


Userlevel 1
Badge +7

Hi all,

Our current Manufacturing Lead Times (as found in ‘Inv. Part’ - ‘Acquisition’) are not accurate.

This is because the calculation used by IFS totals all the values we’ve specified, including the queue times (entered manually) for each work center in the routing of a part. This formula doesn’t seem correct.

 

Case:

Consider part, P, which has an MLT of 100 days.

P could have 3 operations, at 3 different work centers, with 3 different queue times.

WC1 - (queue time against the calendar in working days) = 10 

WC2 = 20

WC3 = 70

 

In isolation, the values for each work center are true. For example, if anther part, P2, has only WC3 in its routing, it may need to wait 70 days based on the loading of the resources to begin work. 

 

However, the original part, P, routed through WC1- 3 doesn’t have a lead-time of 100 days. Since the 70 working days of queue time is greater than the preceding operations, this would absorb the wait time for the 2 prior operations. So, the actual queue time for P would be 70 not 100. 

 

The problem is IFS’s MLT calculation performs a sum of for queue times meaning they end up bloated.

How can this be amended? Is the way we are understanding queue times (and how to state them) correct?

 

cheers, 

 

 

 

 


4 replies

Userlevel 3
Badge +4

Hi,

 

I think you are missing something here. There isn’t any special setting that you have to follow here. I followed the simple steps you provided and it showed the expected results. Have a look;

I have setup 3 work centers as per suggested queue times. (Queue time is in hours to reflect the suggested days 10,20 & 70)

 

Routing for 2 inventory parts are also setup as below. (WC3, ‘SPRAY’ with 70 queue time in as Op3 for P1 and Op1 for P2)

P1:

P2:

 

The MLT  in ‘Inv. Part’ - ‘Acquisition’ tab is showing expected results.

 

 

If you can illustrate your case further I could try to provide an answer. 

 

Regards,

Vibhu.

 

Userlevel 3
Badge +4

Hi,

Further, Queue time is not a complicated thing. It is he average time in hours that an operation has to wait before it can be processed in the work center. This information is used during operation scheduling. So when you calculate Lead time, the queue time will be considered and identified as a ‘Fixed Leadtime’.

Regards,

Vibhu

Userlevel 2
Badge +7

However, the original part, P, routed through WC1- 3 doesn’t have a lead-time of 100 days. Since the 70 working days of queue time is greater than the preceding operations, this would absorb the wait time for the 2 prior operations. So, the actual queue time for P would be 70 not 100. 

The problem is IFS’s MLT calculation performs a sum of for queue times meaning they end up bloated.

 

Hi,

I quoted the part of your post that seems to be crucial. Each operation needs to wait as long as it’s queue time says, but the moment each operation STARTS to wait is only after previous operation is already done. Indeed, they could start to wait at the same time and this would provide 70 days lead time instead of 100. This is really confusing, I’m not sure if it’s ok or not…

Have you tried setting those operations to parallel?

Regards, Lukasz 

Userlevel 2
Badge +7

@JoherM 

Did you find the solution to your concern because we have exactly the same issue.

So, I’m interested to know if you solved it.

Thanks - Carole

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