Deleting requisitions isn’t necessarily going to fix the problem or start to clear them away, especially if they are actually for current demands.  Date alignment is something that takes a fair bit of analysis and understanding and without knowing what the status of the dates on everything are in your system, your question is really only one that begs many more questions, not answers.  I can imagine what state everything is, but it is just a guess which isn’t necessarily helpful to fix the problem.  I don’t know if you operate on DOP, Make to Order but in a make to inventory mode, lots of configurations or none, project oriented business with custom order requirements or everything is off the shelf.  All of those things matter and drive why you are seeing reqs with dates in the past.

1. Are your Customer Order schedule dates / commitments valid, or are they just as inaccurate as the MRP data?  ie, if you are actually meeting your customer commitments a majority of the time, then your throughput and order cycle time must be reasonable, just not date driven.  If you are always late on customer orders, then setting realistic expectations is first step.
2. Are your Purchase Order wanted dates reasonably valid?  Or are your suppliers always late because your wanted dates are unreasonable but in line with the customer order dates?  
3. Are your inventory levels reasonably sized for the volume of business that you are doing or are you always out of everything you need?  Do you have many things on Kanban or is everything make to order?  
4. Are the shop order proposals for valid needs driven but customer orders?  Are they for finished goods to inventory that you never actually get made until you have an actual need?  Meaning, are you kidding yourself that you are making things to inventory, but you really are only making them to customer orders.  The transition of factory mindset from a job shop to inventory level driven tempo is significantly difficult to change around.
5. Have you really analyzed the requisitions and proposals?  If things are reasonably aligned to real demand and MRP is operating correctly, then the requisitions and proposals are getting regenerated every night because they aren’t being acted on.  Maybe they are all real, maybe you don’t run MRP every night, without analyzing a significant portion of them to know whether they are real or not, it is hard to decide where to start with them.
6. Leadtimes are always a good place to start, they don’t have to be accurate to a day or an hour, but they should be reasonable.  Again, analysis is the only way to know where to start.  This takes a team of people who understand what is really going on versus what the system has been told is reality.  After analyzing whether they are super inaccurate, start with some really coarse adjustments.  3 to 5 buckets can make a huge difference on a first cut.  Is the item 5 days, 15 days, 30 days 90 days, or 180+.  Start there and realign items in large swathes if you just don’t know, or use historical delivery data and shop order open/close differential data to set the leadtimes.  Are your calendars 5 day, 7 day, or both?  It matters to be clear.

Finally, if the requisitions and proposals are more than 80% driven by real customer demand, then start with the leadtimes and the customer order schedule dates and work to the middle.  If the requisitions and proposals are garbage and if acted on would flood inventory with unneeded items or they are really old, then pick a date and just kill everything older than that - it might be 3 months, 6 months or a year old, can’t say without knowing the business.  Then start with the planning data, planning methods and triggers for the reqs and make sure MRP is operating to real demands and work from the middle outwards.

One thing I can offer with reasonable certainty, IFS is doing only what it is told to do, so if everything is wrong, it really doesn’t matter where you start.  If most of it is right, then first identify what is grossly wrong and start there.

Shawn - thanks for the thorough reply.  I realize that my question was incredibly general and as you mention, only serves to create deeper questions versus illuminating answers. 

That said, I’m fully aware that IFS is only doing what we’ve instructed it to do - my concern is finding the “best right starting point” in terms of a starting point to addressing the Sisyphean task of baselining our supply chain processes. You’ve offered some great suggestions so I appreciate that. The unfortunate reality is that my predecessors had no idea what they were doing whereas I know only enough to be dangerous . We’re a make to stock company that deals in non-configured goods - so relatively simple in terms of supply chain & customer order complexity. 

Your general roadmap mirrors the one I had in my head, but with much better clarity and what we’re already doing. Sometimes it’s just helpful to be validated ;)  Thank you, thank you, thank you.

Yeap, Shawn has provided a really good answer with ‘tons’ of good input. I just wanted to mention that you could work with the MRP Action Proposals Workbench or MRP Action Proposals and search for the MRP Action Message ‘Plan Supply Past Due’. This message is created for each and every shop order req and/or purchase req that have planned receipt date in the past (In apps10 we have improved this further by adding another  MRP message that is raised when the start date is past due).

So if you search for this message and perhaps sort the data by the Low Level column you can continue with Shawn’s reply. From both MRP screens above you can drill down to the MRP Part Information screen and study how IFS MRP do its BOM explosion and lead time offsetting.

IFS MRP has no problem in creating reqs in the past but it generates Action Messages for it (as I mentioned above). So if you don’t experience any problem with customers who does not get their “stuff in time”, then your lead time data in IFS Applications is too long compared to the actual lead times. Or perhaps you hide the problem with huge safety stocks. Normally lots of Plan Supply Past Due messages tells us that we have some “gorilla” orders in the near future, (or forecast are have increased) which we will have problem to deliver in time. By learning MRP in general and IFS MRP more specific you will not drown in this. I think your future glory will be assured Good Luck!

Related question:  is there a way to drive req’s into the future (i.e. with lead time or the like).  More specifically purchase req’s for finished goods.  IF demand creates a need, MRP is dropping it where needed (with a latest order date potentially in the past).  As specified above, obviously that can’t happen - I would think earliest availability date would be current date / MRP run date + total lead time (by whatever collection of lead time components).  Is there a way to make the “latest order date” no less than current date or MRP run date, i.e. place the req lead time into the future to represent the reality of it. This, of course, means you may be short supply for some period of time - but would prefer that reqs generated/automated by MRP abide by lead time, and short lead time orders only be handled manually. 

@majose Bumping this. How do we configure MRP to push purchase requisitions out to a realistic receipt date based on lead time?

You can’t really push the requisitions into the future unless you have additional demand over the current order level that isn’t needed in the past (ie, safety stock or stock driven future demand).  The only real way to overcome this skewed reality is at the point of conversion to purchase order by setting the Planned Receipt Date to a realistic delivery based on today + leadtime + delivery, etc.  

Doing so at PO Creation and later at Confirmation is really the only way I’ve found to provide sales and manufacturing with realistic Arrivals that can be planned against.  The MRP requisitions are always going to be aligned to their demand which if your orders are behind will always be unrealistic or in the past.