The help for the function explains it pretty plainly.

• When calculating the cumulative lead time for a single part, it looks just one level down and accumulates the lead time to the top. It does not consider the entire BOM structure.

Cumulative Lead Time is always going to be the actual routed time plus transport time on the operation plus any queue time on the work center.  So your example will always be 5 days as it is assumed to be from the full stock point, not from the zero stock and need to order all raw components.

This is easily the most thorough post on the subject and validated by IFS, so it has the full detail

Thanks - it’s that ‘and calculated by the same function’ which is throwing us out.

It does beg the question why is it called cumulative lead time! - The field name is misleading (we were given a Bum Steer by an IFS Partner on this one.

I’ll write a report and they can manually update data if they want in LIVE. Have to be manual process.

We should have stock of items, but some supply chain shocks have meant this has only been noticeable of late in IFS.

If not running the CLT calculation for the Site, you should run MRP, either for the Site or selectively for the part. This needs done in order to re-calculate the low-level codes of each part, which is critical for the CLT calculation. Prior to running MRP, each of the four parts in your scenario probably showed a low level code of -1 on the Manufacturing tab. That is why the calculation returned a value of 5 for your manufactured part, there were no lower levels.

Hi Matt - we are running MRP twice a day site wide and Pur Lead Time, Man Lead Time, CLT daily - in that order. It is not seeing the purchase part lead times, only the man lead time.

@ShawnBerk’s answer explains - though I now have to get the business to understand. Also about to start a Cloud upgrade, so don’t want any custom events in place that will need lifting and shifting

That said @matt.watters  - what are ‘low level codes’ used for?

I’ve just looked at Manufacturing Tab and see that has the correct figure under cum lead time. Just not on Acquisition tab. Think above things might have been getting crossed.

@Matthew did you ever get this to provide the output for the BOM you were expecting, to include the LTs of the purchased components and any lower levels?

After running  Calculate Purchase LT, Calculate Mfg LT, and MRP, when the Cumulative LT Calculation is run for an entire site, leaving the part number field blank (or maybe using a % in apps 10 and previous), this calculation will return the value corresponding to the path through the multi-level BOM that adds up to the greatest LT.

@matt.watters - I didn’t get it working, but soon after I posted my last reply on this I handed my notice in at that company, so spent my final days stabilizing things (and attempting to pass on my knowledge to my boss - that was amusing)

I did write an event to copy from the manufacturing tab to the acquisition tab - which gave them what they wanted.

Currently we’re not using lead time calculations - but it will be one to come back to should that change!