Problem with multiple unit of measure setup

hav

Hi All,
I am using NAV 2009 NA SP1 with demo database.
I am facing problem with the multiple unit of measure code setup with conversion factor and the "Needed Quantity" being calculated in the Order Planning.
I have setup a Test item with below UoM's:-
Base UoM : PCS
Sales UoM: INCH
Purchase UoM: FEET
The relationship between these UoM's is
UoM Qty Per Length
PCS 1 216
INCH 1/216 -
FEET 1/18 -
The Replenishment policy for Test item is Purchase and Manufacturing Policy is "Make-to-Stock".

The use-case is related to door and window industry domain in which a fabricator stock Profiles in pieces (1 piece is of 216 inches or 18 feets) and purchase them in feets.

I have created another item Main which has a Production BOM with single BOM line corresponding to Test Item. The BOM line details is as below
Item Calc.Formula Qty Per Length UoM
Test Length 1 100 INCH
The Replenishment policy for Main item is Prod. Order and Manufacturing Policy is "Make-to-Order".

Next i created a Sales Order and enter sales line for Main item with Qty = 1.
Now when i run Order Planning and calculate Sales Demand, the Main item is listed with Needed Qty = 1 and Replenishment System = Prod. Order.
I then create Prod. Order by clicking Make Order on Planning window.
Next i run Order Planning and calculate Production Demand. The newly created Prod. Order is listed with component line as Test Item, Replenishment Sytem = Purch. Order and "Needed Quantity" = 8.33, UoM = FEET

The calculation goes like this as per my understanding:
100 INCHES of Test Item is being used in the production of Main item.
1 INCH = 1/216 PCS
100 INCH = ?
==> (100 x 1)/216 = 0.46296 PCS
1 FEET = 1/18 PCS
? = 0.46296 PCS
==> 0.46296 X 18 = 8.33328 FEET

So far it is good as the "Needed Quantity" is calculated correctly.

Now suppose if i change the Production BOM line in the Production BOM of the Main item as
Item Calc.Formula Qty Per Length UoM
Test Length 1 100/216 PCS (=0.46296 PCS)
and repeat the above procedure to generate the Prod. Order then what i see in the "Needed Quantity" for Test item is 17.99857 FEET.
I am not sure how this gets calculated to 17.99857 feet. It should be 8.33328 feet.

I have few queries.
1) Is my setup for UoM correct?
2) Is my understanding for calculation of "Needed Quantity" correct?
3) If not, what is the formula to calculate "Needed Quantity"?

Note that i create a Sales Order with sales line corresponding to Test item directly instead of using Main item with a Production BOM for Test item, then the Order Planning gives correct quantity irrespective of whatever UoM i keep.

Any idea how does this works.
Please help.

kriki

[Topic moved from 'NAV Three Tier' forum to 'NAV/Navision Classic Client' forum]

Sog

I can only anwer your first question and the answer is no.
The Base unit of measure should always be the smallest unit.
In this case Inch. If you select piece as with a qty. per uom different as 1 you should get an error message.
This is to minimize rounding issues.
Better to set the uom up like:
Base & sell: Inch = 1
Purch: Feet = 12
Pcs= 216.

Next to setup is the rounding precision. Do you want to have your setup to have one inch minimum or is 0.1 or half an inch 0.5 as the smallest unit possible.This way you'll have a much easier time to maintain your stock. If not you could have a stock of 1.45678 or worse. As for the needed qty. I don't have your answer (yet).

hav

Thanks for your reply.

I have gone through some of the post in this forum related to multiple UoM but some say that you setup Base UoM as the smallest unit whereas some say that it should be UoM in which you stock your inventory.

Savatage

hav wrote:

Thanks for your reply.
whereas some say that it should be UoM in which you stock your inventory.

Really? If so it depends on what you're selling in your case Making the smallest value the base it the way to go!

Base = 1 inch
Foot = 12 inch
Pcs = 216 inch

this will give you nice round numbers to work with instead of crazy numbers like this.
0.46296 PCS
8.33328 FEET

hav

hav wrote:

Really? If so it depends on what you're selling in your case Making the smallest value the base it the way to go!

Base = 1 inch
Foot = 12 inch
Pcs = 216 inch

Note that the physical stock is maintained in Pieces, say 500 PCS = 500 x 18 = 9000 FEET.
If i keep the Base UoM as INCH and run the Physical Inventory Journal to take physical count then it will show all journal lines in INCH instead of PCS. The alternative in this case would be to manually go into each journal line and change UoM from INCH to PCS.
Is this feasible?

hav

Another thing i noticed is that on Phy. Inventory Journal, it does not allow to change the UoM from Base UoM. It gives error "Phy. Inventory must be No on journal line......"

hav

I would be thankfull if anyone of you can determine and tell me what is the formula used to calculate "Needed Qty" on Order Planning window.
Why does it calculate 17.99856 instead of 8.33338?
Any idea?

Savatage

conversions will be needed either way you go.

On reports (if using INCH as base) you can divide the Qty On Hand / Sales Unit Of Measure Qty to give you the "look" your seeking.

Else I'd rather have the Phy Inv Journal show me.
100 inches rather than .4630 pcs and you'll avoid rounding issues.

hav

Hi,
I have found out the reason why "Needed Quantity" shows 17.99856 instead of 8.33328 FEET for Test Item.
The reason is the "Rounding Precision" set for the Test Item.
By default it was set as 1. This means that on Production BOM Line even if my Quantity was 0.46296 PCS, it considers it as 1 PCS and hence the Order Planning gives demand quantity = 1 PCS = 18 FEET (17.99856)
I then changed the Rounding Precision on Test Item to 0.00001
and now if i run Order Planning, it shows "Needed Quantity" as 17.99856.

Thanks for your cooperation.