mrp with safety stock

On 1 march, I have an FG item setup with multi level bom structure and route. I have on hand stock 200 qty and I setup the safety stock for this item is 500 qty. The coverage group setting is using Requirement. On the same day, I run master scheduling. Ax propose me a planned production order with 300 qty. Due to capacity constraint, the “delivery date” in the planned order screen is 18 March and the “requested date” is on 1 march. I firm it to become a production order.
On 8 march (1 week later), without any changes, I run the master scheduling again. Now Ax also suggest me a planned production order with 300 qty. This time, the “delivery date” in the planned order screen is 22 March and the “requested date” is on 8 march.
Since I have created a production order which the delivery date is on 18 March, why when I run the 2nd MRP, AX does not consider it? Ax suggest another planned production order. Another weird thing is Ax give action message to CANCEL the previous firm production order.

If I roll to 3rd week, I believe AX will suggest the same result which mean my FG will always not able to fullfil, since AX ask me to cancel the firm production order and propose me a new planned production order. Please advice.


You would have to tell us all of your item coverage settings at that warehouse and all of the coverage group settings used in the item coverage.

You would also have to show us the net requirements and the status of the first production order.

AX will certainly do this if you configure it to do this.

Hi Adam,

My coverage group setting for all items are:

  1. Coverage code = Requirement

  2. Coverage time fence = 40 day

  3. Negative day = 0

  4. Positive day = 40

  5. Explosion time fence = 40

  6. Capacity time fence = 40

  7. Action and futures = 40

The production order status after firm is Release status.

On the net requirement screen, Ax show that the minimum = 500 (= safety stock level).

There are 2 records in the middlw section which is on hand (qty = 200) and 1 planned production order (qty = 300). This planned prod order requirement date is 18 March.

On the pegging section, the planned production order is peg to the safety stock, requirement date is 1 MArch.

Kindly advice is there any setting that i can fine tune so that AX will consider my firm production order when i run the 2nd MRP.


Because your negative days are set to ZERO you are telling the system to never allow a negative stock position. The system takes the reorder point as the trigger, this when not using item coverage will always be today I believe. So it knows you need it today, works out the lead time, works out you do not allow negative days and plans a new order and tells you to cancel the old one.

If you had this set to 20 for example this would not happen, you would get an action message to reschedule the original. If however you do not understand negative days I suggest you set it to 40.