safety stock qty & inventory relation

Dear All, I will continue my discovering in make to stock planning parameters available in navision. These following situations I describe to ease understanding= Reordering policy = maximum qty 1. Item A replenishment system= production order inventory = 100 pcs Safety stock = 300 pcs RoP (reorder point) = 500 pcs Maximum Inventory = 500 pcs RoC (reorder cycle) = 1 w Location code = nil 2. Item B replenishment system= purchase inventory = 190 pcs Safety stock = 300 pcs RoP (reorder point) = 500 pcs Maximum Inventory = 500 pcs RoC (reorder cycle) = 1 w Location code = nil Demand = SO qty = 450 pcs (order date/work date=040506, requested del. date = 041506) Planning worksheet (MPS/MRP calculation)with date filter 030106 to 050106 results= 1. Item A = 350 pcs due date 030106 ; Accept action message = No 2. item A = 500 pcs due date = 041406 3. Item B = 810 pcs due date = 022606 ; Accept action message = No 4. Item B = 500 pcs due date = 041106 Based on the results I conclude = total qty item A = 850 pcs SO request = 450 pcs inventory = 400 pcs → (does it means inventory = 100 pcs and safety stock = 300 pcs ?) total qty item B = 1160 pcs SO request = 450 pcs Inventory = 710 pcs → I wonder why the the result is 710 pcs and from where this result comes from ? if safety stock > current inventory, does it mean the system will make an order proposal to fill the inventory to become safety stock + current inventory ? I am thankful for your attn & reply beforehand…I really need your assistances… rgds, Mark

Hi Mark By picking the “Maximum Qty” policy you have picked the one policy that has lots and lots of “issues” attributed to it. There have been some recent postings on this issue in this forum. Firstly you are starting at a point which you would not meet if your parameters were set and you were running the system regularly. Your inventory is already below your settings, and then you load sales orders. Essentially the initial dip below the reorder point would be planned for, then it will plan for the subsequent sales orders. In your example your inventory is 100, the safety stock is 300 to handle fluctuations in stock, but as your reorder point is 500 the replenishment is already triggered by your stock dipping beliw 500. So for Item A your stock is 100, there is a SO for 450, leaving you 350 short, so a plan is made for 350. However you have a RP of 500 so a second plan is made to replenish this, at the maximum quantity to reach the RP. The dates look wrong, but I would need to set it up to verify your finished settings, and of course it maybe a known “issue”. For Item B your stock is 190 this is a component of A? You do not say but I am assuming it is. Item B is now required in one order of A for 350 and one order of A for 500. For the 350 fulfillment it also looks at the the maximum inventory, the reorder point as well as the inventory. So you have 190 in stock, to get to the reorder point you need 310. You also need to meet the 350 pieces of the order for A. As your maximum inventory is 500 the system will take the 310 to get you back to the reorder point and then add a further 500 as the next order modifier as you need more (this is a debateable calculation, and I am extrapolating from your figures, not testing). This will put your available inventry all fine by the reorder point. Then you have the second order for Item A. This is for 500, and therefore B plans for another replenishment of 500 as it is required. You state the total inventory for A incorrectly. Initial Stock +100 SO -450 Replenishment +350 Replenishment +500 Total = 500 For Item B you have this wrong as it is not planning for the SO, but for the demand driven by A Initial Stock +190 Requirement -350 Requirement -500 Replenishment +810 Replenishment +500 Total = 650 The difference in finishing positions is determined by the different opening stock and the different demand patterns. Worry about the reorder point first. Not the safety stock. I would also recommend you get your position pre-sales loading in a position where it generates nothing in MRP as this will make it easier to understand.

Dear Steven, I have tried your explanation and it worked good. Tks a lot for your reply. rgds, Mark