Tag: Coverage group

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.

 

Checklist for improving MRP performance – Part 1: How to run MRP

If Master Planning (MRP) runtime is too long, here are a couple of simple things you can try in order to improve it. The list was compiled for Microsoft Dynamics Ax 2012, so parts of the checklist may not apply to earlier versions. 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. It is also recommended that the test environment is as close as possible to the production environment in terms of data volumes: number of products and number of transactions. If you are running MRP in recurrent batch, note that some of the settings will be cached, so it’s better to make the parameter change and re-create the batch and then run MRP again.

 

1. Use helpers for master planning

Using helpers (parallel processing threads) during master planning will most likely improve the runtime. Request one or more helper threads when running master planning, by setting the Scheduling helpers – Number of helpers parameter in the Master scheduling dialog to a value greater than zero.

More information about helpers can be found here:

TechNet: http://technet.microsoft.com/en-us/library/gg242496.aspx

InformationSource: https://informationsource.dynamics.com//RFPServicesOnline/Rfpservicesonline.aspx?DocName=TC2014+Help!++MRP+is+slow%7cQJ4JEM76642V-8-1608

Also make sure you have applied to the Ax environment the latest hot fixes related to helpers. Below are just a couple of KBs that you should consider installing or porting to your AX version:

KB article 2693422 https://mbs2.microsoft.com/Knowledgebase/kbdisplay.aspx?WTNTZSMNWUKNTMMYTPNRYVZNNPWYSWVQRWURNYWNXVKVRNQY

KB article 2690230 https://mbs2.microsoft.com/Knowledgebase/kbdisplay.aspx?WTNTZSMNWUKNTMMYTPNRYVZNNPWYSWVQUOLKVSMVQULNVYQT

KB article 2862912 https://mbs2.microsoft.com/Knowledgebase/kbdisplay.aspx?WTNTZSMNWUKNTMMYVWQXNRNXTVKNSKYVQNYNRZQRRRTPMQYY

 

2. Number of helpers used during master planning needs to be less than or equal to the maximum number of threads allowed on the batch server

It makes no sense to have the number of threads requested by planning greater than the sum of available batch threads on all batch servers in the selected batch group that runs master planning. Set the number of master planning helpers to be lower than the sum of available batch threads on all batch servers in the selected batch group to run master planning or increase the number of threads on selected batch servers.

To check the number of available batch threads per server/batch group go to System administration – System – Server configuration

 

3. Use multiple AOSs for master planning

Using more AOSs during master planning will most likely improve the planning runtime. It is also very important that you make sure no other lengthy routine is running simulataneosuly with master planning. It is also very important that you make sure no other routine requireing locks on tables used by master planning (for example InventTrans, InventSumLogTTS, ReqItemTable, etc) is running at the same time as MRP. 

 

4. Configuration keys that are not actively used should be disabled

For example, when Process Industries functionality is used, a lot of additional planning logic is being triggered, like for instance expiration dates for batches. This will increase the master planning runtime. If Process Industries functionality is not used, make sure the ‘Process manufacturing’ configuration key is switched off.

 

5. Action message usage

Calculating action messages leads to longer master planning runtime. If action messages are not analyzed and applied on a regular basis (daily, weekly, etc), consider disabling the calculation during the master plan run, by making sure the Action message time fence is 0 on the master plan you are running (Master planning – Setup – Plans – Master plans). Also make sure all the coverage groups have Action message setting disabled.

 

6. Futures usage

Calculating futures leads to longer master planning runtime. If you are not planning BOMs or if propagating delays from supply to demand during planning is not needed for you, consider disabling futures calculation during MRP, by making sure the Futures time fence is 0 on the master plan you are running. Also make sure all the coverage groups have Futures setting disabled.

 

7. Number of tasks in a master planning helper task bundle

Changing the number of tasks in the task bundle may have a positive effect on the runtime. The number of tasks in a bundle controls how many items are planned together by a single helper. It is recommended to increase the number of tasks when the number of items is very large (hundreds of thousands) and decrease the number  of tasks otherwise. In most cases it is a trial and error approach before an optimal value is determined. Remember to change this value as you add to Dynamics Ax more and more products!

 

8. Caching during master planning should be set to Maximum

Master planning logic is controlling the amount of caching used. This parameter is obsolete and is a candidate for removal in future versions of Microsoft Dynamics AX. In all the companies master planning is executed, consider setting Master planning parameters –  Use of cache to Maximum

Separating tactical and operative planning for master scheduling

Master scheduling has to deal with an increasing number of transactions, especially if a company goes through  a lean transformation. The lean transformation leads to shorter lead times and smaller batch-sizes. Having reached the ideal of batch size one may suddenly increase the number of transactions that master scheduling deals with by factor 10 to 100.

This is especially true if your configuration is set for your operative scheduling – usually covering few weeks, or in the lean ideal a few days. But if you use the same configuration to calculate your tactical plan, that usually spans over a couple of month up to a year, the volume of transactions can be considerable. At a customer review we found more than 7000 planned transactions for a category C part – a part that should be planned on minimum stock level instead.

In a meeting I had with the planning team of the customer, it became transparent, that one of the challenges is to configure the lead times as well as the positive and negative days for master scheduling. You need to start with analyzing how demand patterns of different products and materials behave. Unfortunately, the formula “longer is better” does not apply here. Having 200 planned purchase orders in the future for an item that has a purchase lead time of only few days is – in lean terms – waste.

To limit the runtime of master scheduling on one hand and the number planned orders and action messages on the other side, It is recommended to work with 2 different plans:

  • An operational plan, that uses fences and other parameters from the coverage groups and item coverage, not overwritten by the plan itself. The operational plan is updated every night.
  • A tactical plan that overwrites the planning and coverage fences to a longer horizon to make a full explosion in all details. The tactical plan is re-calculated once a week, usually on the weekend. Firming of planned orders should usually not   be done based on the tactical plan.

 It is recommended to structure the coverage groups by demand patterns and use item coverage only to punctually override settings for products, that require special treatment or to evaluate modified behavior.

 Negative / Positive days:

  •  Positive days:
    Positive days allows master scheduling to use a planned receipt to cover a specific demand, that lies n days before the demand. In other words, it allows master scheduling to plan for excess inventory to minimize the number of planned orders. To consider actual on-hand for any demand, the positive days have to be at least as long as the coverage fence. This is valid for low turning products or products that are covered by high security stocks. For quick turning products that have a regular replenishment or receipt per day, week or month  (EPEI = n days) should use positive days that are close to the EPEI. Another way of expressing this: positive days should not be more than MAX 2 times inventory  turnover rate.
  • Negative days:
    Negative days allows master scheduling to use a planned receipt to cover a specific demand, that  lies n days AFTER the demand. It basically allows Master scheduling to plan for being late. It is important to understand that in a supply  chain this setting can cumulate for every planning step with the end result of allowing to be late on almost every planned order. Negative days are needed when the inventory or purchase lead times are longer than the corresponding Sales lead times, to avoid multiple creation of planned orders for the case where a new demand that cannot be covered is placed earlier than the new planned order will be scheduled.
  • In AX 2012, the new possibility of Dynamic negative days have been introduced.
    Negative days can be hard to set, as lead time can be different for products assigned to the same coverage group. That is where Dynamic negative days should be used (found under master planning/ setup / master planning parameters). Once dynamic negative days is set, the lead time defined on released product (default order settings, site specific or item coverage) will always be the minimum negative date counted from today. If a demand is calculated in the future, then  negative days will be equal to number negative days set on the coverage group.
    This feature is a significant change in defining negative days, and should be much easier to define. When calculating with dynamic negative days, the negative days settings should now be 0-5 days – depending on the demand pattern of the related product, and not as earlier recommended = lead time. The usage of dynamic negative days will decrease actions and futures. + all issues that are within lead time will always see receipts within lead time. Especially useful for long lead time items, where periodic or min max is used as requirement policy.

For the improvement of the settings of the operational plan the following guidance should be considered:

  • The coverage fence of  purchased material should not be longer than double the lead time of the material, ideally only 2-3 weeks longer than the purchase lead time. The operational plan should only contain planned purchase orders that are needed to take action by the planner, not the tactical forecast. If a planner needs a longer term view he can consult the tactical plan. For purchase products the positive days should be mostly equal to the coverage fence. Purchase
    material should not have negative days = the purchase lead time or even better, use Dynamic negative days. Then purchase material should run with 0 negative days.
  • Planned transfers that are used for replenishment and internal logistics between warehouses should not have negative days. The positive days should also be very small, ideally 0 to create the planned transfers at the point in time that the     transfers are really needed.
  • Finished goods should only have negative days, if the sales lead times are smaller than the corresponding inventory lead times (or for finished goods that are directly purchased, the corresponding purchase lead time). The negative days would then be the delta between sales lead time (first possible new demand) and the inventory or purchase lead time (first possible new supply). And again, the alternative is to use the Dynamic negative days principle, where again the negative days are calculated automatically based on the lead times.

Master scheduling with Microsoft Dynamics AX is truly a dynamic task. There are many ways of influencing the  planning results and the performance of master scheduling by modifying the right parameters. The resulting plan can only be as good as the configuration allows – and of course, dependent on the quality of the actual and the forecasted demand. We would love to hear about your experiences and your best practices related to positive and negative days and Dynamic negative days. We are also interested in your experiences with multi-plan strategies.

Meet the Microsoft Dynamics AX manufacturing team at the AXUG Summit next week or at Microsoft Dynamics AX Technical conference 2012 in the manufacturing focus room.