Positive days in master planning

So what exactly is positive days in Master Planning?

Its a simple concept. Say a purchase order is dated 30th of June and a sales order is dated 31st of December. There are no issues and receipts in between. When master planning logic attempts to match the sales order with a purchase order, the concept of positive days kicks in.

After all planning is theoretical. In reality the item may not remain on-hand for six months time, there is a good probability that a sales order will come up during the first three months and consume the item (i.e. the purchase order). In this case you set the positive days to 90, so that the sales order of 31st December is not adjusted against a purchase order of 30th June.

Obviously this concept has problems. The positive days will work fine when quantity is small. But what happens when say you have a receipt of 10000 numbers, it will not be practical to assume that all 10000 are going to be in stock for 90 days or 180 days. You need to say that 20% will most likely be consumed in the first 30 days, 30% will most likely to be consumed in the next 30 days and so on....

The answer to this problem is to apply ageing to the positive days in master planning. This will remove the need to put in detailed sales forecast and to consume the sales forecast (your customers may like this).

The downloadable zip file below contains xpo file (with labels in language en-us) and an excel spreadsheet to set the data up and test the project.