How to set up a BoM

Paul_D · **Joined:** Mon Oct 26, 2009 5:59 pm **Posts:** 4

I have some troubles setting up a correct BoM structure and Routing

As example I will need to produce a product MIX
One gram of this product contains 0.337 grams of component A
The standard BoM will not allow me to enter sufficient digits so I tried setting up a BoM for a quantity of 100 grams of MIX requiring 33.7 grams of component A.
Running the product cost structure report will tell me the cost for a given 200 grams of MIX stated as the requirment for actual 20000 grams

It gets more confusing when I set up the Workcenter and Routing.
Our Workcenter will produce the MIX as a batch.
A batch can be up to 2000 grams and will take 2 hours processing.
I set up a Workcenter M with a capacity of 2000 units and 2 hour running time and its cost.
This I connect via a routing into the BoM.

Running the product cost structure report again will tell me the cost for 200 grams of MIX stated as the requirment for 20000 grams but with the 2 hour processing cost added the final cost component is just 1% of the actual processing cost.

How should I set up my Workcenter, Routing and BoM to get a correct costing report?

moiseslopezuk · **Posted:** Sat Mar 06, 2010 9:38 am

Dear Sir,

Here I am facing same problem and I try to find out solution but not get it yet. If you get the solution than please let me know and if i get it than I really share that with you!!!

Paul_D · **Joined:** Mon Oct 26, 2009 5:59 pm **Posts:** 4

Dear Moses,

As up till this moment we have not solved the problem.
We have however found this to be a serious flaw in OpenERP.

Also introducing additional units of measure will create even bigger problems.
I tried introducing a unit of measure in milligrams and specifying a BoM for 1 gram issuing xxx milligrams of components. Apparently OpenERP is just using a figure in units for its calculations without taking notice of the ration and units of measure. (e.g. 1 gram + 1 milligram = 2 gram ?!)
I have not found out how the ratio or conversion factors are supposed to work.

This also seem to be a problem using different currencies on sale and purchase orders each currency is equal

alex_joni · **Joined:** Fri Sep 25, 2009 9:30 am **Posts:** 15

Paul_D wrote:

I have not found out how the ratio or conversion factors are supposed to work.

You basicly create more than one unit of type weight.
The ratio specifies the difference between them.

for example:
basic unit, gram - factor 1
milligram - factor 0.001
kilogram - factor 1000
etc.
That way OpenERP will know how the units relate to each other, and will add them properly.

Regards,
Alex

Paul_D · **Joined:** Mon Oct 26, 2009 5:59 pm **Posts:** 4

Dear Alex,

I did just so but the system is not correct.
Please have a look and follow my example

I created 3 products
- MIX UoM = gr
- Component A UoM = gr @ 10 euro/gr
- Component B UoM = gr @ 20 euro/gr

I create a routing requiring 2 hours @ 45 euro/hr
(My work center used has a capacity of 2000 gr/cycle)

I create a BoM for 1 gr of MIX consuming
- 337 mg Component A
- 547 mg Component B

Checking the BoM structure is showing all is correct with correct units.

I then wanted to check the product cost structure for 50 gr of MIX

The report shows I will be using
16850.0 gr Component A
27350.0 gr Component B
and charging 90 euro for the manufacturing hours

Resulting in an overall cost price of 715590.00 Euro for 50 gr

Clearly this is rubbish as it should be 805.50 euro for 50 gr !!
Is this to be considered as a Bug?