Checklist for improving MRP performance - Part 2: How to setup planning parameters

If Master Planning (MRP) runtime is too long, here are a couple of simple things you can try in order to improve it. You must, of course, try these out on a test environment first and, if you see an improvement, apply the same settings to the production environment. It is recommended that you apply one setting at a time, so you can get a good sense of what helped and what didn't. Some of the settings below will not only have an effect on runtime, but may also improve your plan quality. The list was compiled for Microsoft Dynamics Ax 2012, so parts of the checklist may not apply to earlier versions.

1. Items assigned to the same coverage group should have similar lead times

Coverage parameters, such as the coverage time fence, negative days and positive days, relate to the lead times of the items inside the coverage group. If there is a disconnect between the lead times of the items and these parameters, master planning may create unnecessary planned orders, leading to potential suboptimal planning outcome and potential longer execution times. Items assigned to the same coverage group should have similar lead times.

Be sure at all times that you have the latest hot fixes related to lead times applied to your environment. One example is KB article 2938941: https://mbs2.microsoft.com/Knowledgebase/kbdisplay.aspx?WTNTZSMNWUKNTMMYZWLSWZQTLLRPPXLZNRORZMMMSSMTMNPU

2. Master planning parameters - Use dynamic negative days parameter should be checked

The negative days setting is connected to the lead time of the items. If the negative days are less than or equal to the item's lead time, unnecessary planned orders may be created. Consider the following example: current date is 1st May, there is a sales order for 1 piece of item A on 5th May, item A has a lead time of 6 days and there is a purchase order for 1 piece of item A on 8th May. The negative day setting is 2, which is less than the item A's lead time. Master planning will create a new planned purchase order for 1 piece of item A, which, according to the lead time will be delivered 7th May. This is just 1 day before the already existing purchase order. Firming this new planned purchase order may lead to unused inventory piling up. Creating planned orders that are not useful increases master planning runtime for no reason.

Checking Use dynamic negative days parameter makes sure that the connection between the item's lead time and the negative days is taken into account during planning. Consider the following example: current date is 1st May, there is a sales order for 1 piece of item A on 5th May, item A has a lead time of 6 days and there is a purchase order for 1 piece of item A on 8th May. The negative day setting is 2, which is less than the item A's lead time. Master planning will not create any planned purchase orders. The sales order will be fulfilled using the existing purchase order.

3. Negative days parameter on the coverage group should not be less than the lead time of the items assigned to the coverage group

If the negative days are less than the item's lead time, unnecessary planned orders may be created. Consider the following example: current date is 1st May, there is a sales order for 1 piece of item A on 5th May, item A has a lead time of 6 days and there is a purchase order for 1 piece of item A on 8th May. The negative day setting is 2, which is less than the item A's lead time. Master planning will create a new planned purchase order for 1 piece of item A, which, according to the lead time will be delivered 7th May. This is just 1 day before the already existing purchase order. Firming this new planned purchase order may lead to unused inventory piling up. Creating planned orders that are not useful increases master planning runtime for no reason.

Negative days parameter on the coverage group should not be less than the lead time of the items assigned to the coverage group.

A KB article you should make sure you have installed is 2736992 https://mbs2.microsoft.com/Knowledgebase/kbdisplay.aspx?WTNTZSMNWUKNTMMYMWMSYTMOWZPWLSWNTQWWSZZVXMWPMSOX

4. Positive days parameter on the coverage group should not be 0 or empty

If the positive days parameter on the coverage group should is 0 or empty, then existing incoming orders will not be taken into account for planning and new planned orders will be created. Note that on hand will always be consumed, regardless of the number of positive days set. Creating planned orders that are not useful increases master planning runtime for no reason. Firming these planned orders may lead to unused inventory piling up. Positive days parameter on the coverage group should not be 0 or empty.

5. Items that are regularly procured or produced should be assigned to coverage groups where the Positive days parameters is equal to the item's lead time

If items have lead times bigger than the Positive days parameter on the coverage group, unnecessary planned orders may be created. Creating planned orders that are not useful increases master planning runtime for no reason. Firming these planned orders may lead to unused inventory piling up. Items that are regularly procured or produced should be assigned to coverage Groups where the Positive days parameters is equal to the item's lead time.