Lot Size Planning for Procurement

[Former Member]

Hi guys

In our company we work with minimum lot sizes for procurement, and we need to configure minimum lot sizes for procurement in the SNP optimization run. It´s posible to do it in SNP, pls can someone tell me how to configure this in SNP?

David

[Former Member · Accepted solution]

Hi David,

Please confirm are you using fixed lot size?

If fixed lot size is used in material master, then system ignores

the minimum lot size.

Regards

R. Senthil Mareeswaran.

[Former Member · Accepted solution]

Hi senthil

I tried using both lot-for-lot and by period. but the system is ignoring the minimun lot size for purchase requisition. I also set the discretization in the PPM .

Julien: when i say procurement i mean external purchase requisition (to vendors). When I run the SNP optimizer i need that the distribution receipts planned (in this case external purchase requisition) came with a minimun lot size.

Regards

David

[Former Member · Accepted solution]

Hi David,

If you are talking about external procurement it is a different matter:

You do not use PPM or PDS... so the first indicators we gave you are useless (as well as the descete indicator on the PPM/PDS)

You need to use the following indicator on the optimiser profile:

Min. Transportatn Lot Size

Integral Transportation Lots

Additionally check your customizing:

SPRO:

Advanced Planning and Optimization

Supply Chain Planning

Supply Network Planning (SNP)

Basic Settings

Maintain Global SNP Settings

Check the field "Opt.: Transp. Lot Sz"

In your case you should have the option Location Product/Transportation Lane (and not (Transprortation Lane only)

With this, your scenario should work fine!

Thanks and Regards

Julien

[Former Member · Accepted solution]

Hi Julien

Thanks for your really helpful answer. it´s working actually really good.

I have only one more question: When I start using costs the tool began to behave in a strange way, specifically when I used the procurement cost. you know why the tool do that? it does not pay atention to the lot size define in the product-location

Regards

David

Edited by: David Gutierrez Suarez on Sep 2, 2009 10:53 PM

[Former Member · Accepted solution]

Hi David,

What do you mean by behave in a strange way? DO you have an example?

Additionally are you using procurement cost from the product master or do you have a transportation lane?

Are you using cost function?

Thanks and Regards

Julien

[Former Member · Accepted solution]

Hi Julien, thanks very much for your quick response.

By behave in a strange way i mean that the SNP run ignore the Lot size only when i used procurement cost from the product master.

This is what i have from the product master for the product A, for all the runs i´m using a storage cost of 1 x day:

Base unit: KG

Minimum lot size: 1500

Maximun lot size: 2´500.000

Rounding Value: 100

Stock on hand: 739.63 KG

When I run the SNP optimizer without costs, the tool order a purchase requisition for 1500 KG (week 42).

When I used cost in the transportation lane the SNP run order a purchase requisition for 1500 KG (week 42).

But when i used only a procurement cost from the product master the SNP run order different purcahse requisition for 6,95KG (week 42), 140KG (week 43), 140 (week 44), 560KG (M 11).

I tried also with cost function, but the tool behave in same way as using procurement cost.

Regards

David

[Former Member · Accepted solution]

Strange it is...

One comment though: Normally if you have a transportation lane the procurement cost in the product master is ignored.

So basically you should not used this product master cost in your scenario.

You can confirm that by analysing the cost in the optimiser log. (it should be based on the transportation lane cost only)

Having said that I am not able to explain this strange result : this cost should just be ignored in my opinion. IT should not decide if the model is discrete or not...

You could have a look at the log to see if the discrete settings have been considered (compare the trace of a working solution with a non working solution; and look for DISCRETE).

You might have to open an OSS for that, but since your are not supposed to use it... I am not sure it is worth...

However if you find the answer let me know!

Good luck

Julien

[Former Member · Accepted solution]

hi julien

your solution is working perfect, the only problem is that it is taking long runtime in the solution calculation (more than 15 hours). We tried using a lot size profile in the transportation lane, or only using the values in the marter product. What can we doo to improve the performance of the SNP optimizer run??

Thanks

david

[Former Member · Accepted solution]

Hi David,

I am glad to hear that.

Regarding your performance issue: it is very usual to have long runtime when using discrete model.

The complexity of this model is much higher than a linear problem; so the optimiser takes time to find THE optimal solution.

However there is a lot you can do to make it better:

1. Split your model: instead of running 1 big optimiser, run serveral smaller one in parallel.Ensure your model are all independant (e.g. no common product or resource)

2. Use decomposition: (product/ time/resource; based on your scenari) to simplify the porblem, hence speeding the solution.

3. Set a maximum time

You do not have to wait for THE optimal solution. The optimiser can sometime very quickly find a very good solution; the last hours are spent "fine tuning" it. Potentially, you might not be able to see the difference between a 4h job and the 15H one).

Hence SAP advises to set a maximum runtime when working with discrete model.

The question is how to define this maximum time to optimise the ratio solution quality / runtime.

Answer: test it, check the result. Be aware that perfomrance testing for the optimiser can take a while.

4. fine tune you optimiser setting

There is a couple a finetuning that can be done to improve performance, especially for discrete model.

I will not be able to help you woth that.

As far as I am aware only the SAP optimiser team has the expertise to help here.

I strongly recommand to contact them; their help is often invaluable. They will also help you to define the 3 first points.

I hope this will help you.

Thanks and Regards

Julien

[Former Member]

Hi David,

For configuring minimum lotsize for planning procurement, you need to maintain

lotsize tab (Quantity and Date determination) in /sapapo/mat1 transaction of APO.

In SNP optimisation run, the system considers the minimum lot size as an additional

constraint when calculating lot sizes for orders.

This value specifies the minimum quantity in each order and period. If this value is

larger than the minimum lot size defined at the PPM, the SNP optimizer takes into

account the value given here, if not, it uses the value from the PPM.

You have to choose the discrete optimization method in the SNP optimizer profile

and enter a discretization horizon in the Minimum PPM Lot Size field of the Discrete

Constraints tab page for the SNP optimizer to be able to take into account the minimum

lot size specified here.

Regards

R. Senthil Mareeswaran.

[Former Member]

Hi senthil

Thanks for your answer. I went to lotsize tab (Quantity and Date determination) in /sapapo/mat1 transaction of APO and i put a minimun lot sizes of 25 KG and a rounding value of 25KG . I also choose the discrete optimization method and I enter a discretization horizon in the Minimum PPM Lot Size field

Then I run the SNP optimization, but the results are not the expected, because for this product SNP suggest Purchase requisition for 88.37KG. It ´s not suppose to make a purchase requisition for 100KG?

Regards

David

Edited by: David Gutierrez Suarez on Sep 1, 2009 5:08 PM

Edited by: David Gutierrez Suarez on Sep 2, 2009 12:54 AM

[Former Member]

Hi,

Did you set the Discretization indicator in the PPM? Please check and confirm.

Thanks,

Satyajit

[Former Member]

Hi David,

Indeed the discretisation is required.

Use also the second indicator: Integral PPMs/PDS. (in addition to Minimum PPM/PDS Lot Size)

When you say procurement, you are talking about internal procurement isn't it?

Good luck

Julien