Posts Tagged ‘Manufacturing’

Calculating a product cost with OpenERP

Last week I had the opportunity to try a very useful module that, IMHO, should be included in OpenERP core. This module is product_extended and can be found in the extras repository, you can download it with the following command:

#  bzr branch lp:openobject-addons/extra-6.0

This module does many things, among them shows the product last order for a supplier and its date. But what is really interesting is that it calculates a product cost based on its Bill of Materiales. In order to do that, first you need to check the “Compute Standard Price” check box in the product form,

Then, you can either click on the “Compute Standard Price” button or check it in the product bill of materials (a product can have more than one bill of materials). In the latter, you can find the product information on the Bill of Materials form.

You can calculate the standard price by clicking on the “Compute Standard Price” wizard on the right of the BoM form. How is this cost calculated? This is the interesting part, it takes into account the product cost of each product, plus the hours and cycle costs of every workcenter that is involved in its routing. A very useful module.

It needs a minor change in order to make it work with OpenERP 6.1 but you should try it, I highly recommend it


Data integrity issues in MRP implementations

December 22, 2011 Leave a comment

A good description of the data integrity issues found in MRP implementations can be found in the article on MRP in Wikipedia. In a nutshell, if the

English: MRP

Image via Wikipedia

information in your manufacturing system is bad, don’t expect its planning to be any better (or GIGO). While you are implementing the MRP module in OpenERP, you should pay attention to the following information items in your systems:

  • Lead-times: critical for the timing phase of your planning. If production or supplier lead-times are not accurate, don’t be surprised to find planning dates that are not realistic.
  • Stock levels: very critical, since all the procurements are created when the stock levels drop down below its reorder point or when a customer makes an order (depending on how you have your system set-up)
  • Bills of Materials: your system will procure either raw material, work in process inventory or end-items. Which items it will procure depends on the accuracy of Bill of Materials. Your BoM needs to reflect how your product is assembled. I found some places where the BoM only reflects the cost structure of the end-item, and that is wrong. The cost of the end-item is a different problem that needs to be addressed in a different module than the manufacturing module.
  • Products: your system needs to have all the products you procure (either by purchasing or manufacturing) and sell. And its description needs to be complete.
  • MPS, or production schedule: needs to be available in order to make the plan. In all the manufacturing plants there is a production schedule. People might not be aware there is one, but actually you can find it in the daily or weekly manufacturing plans.
  • Reorder points: you need reorder points (minimum and maximum stock levels) in some products in order to not disrupt your quality of service. We will not get into the calculation of these items (by now)

    We will get into more detail on these items and how to address them in further posts


What is a product in OpenERP?

Supply chain diagram black arrow - flow of mat...

Image via Wikipedia

A product in OpenERP can be many things at the same time. They can be either products to be sold, raw material or componentes purchased from suppliers, or work in progress pieces needed in the manufacturing process.

  • A product that can be sold is a product that will be listed on the products list when you are creating a sales order.
  • A product that is raw material is a product used in the manufacturing process and is procured from suppliers

You specify whether a product can be sold or purchased in the product form:

There is a third option that is not listed in the product definition form, and it is the fact that a product can be a work-in-progress component of the manufacturing process. In order to do that, you need to create a product and keep the “Can be sold” and “Can be purchased” check boxes unchecked. What is important to keep in mind is the Supply Method, where you have two options, “Buy” or “Produce”. If you specify “Buy” the product will be purchased from suppliers. If you specify “Produce”, a production order will be created in order to procure this component.

This  is important to keep in mind when you are importing information from another system. Most of the times you will import the products to be sold or the raw material to be procured, but we forget to import or create the work-in-progress components. We realize this problem when we try to create production orders, since those orders will require Bill of Materials that are missing the required work-in-progress components.

On a next post, I will cover my experiences so far with importing data into OpenERP,


Getting started with the OpenERP MRP module

March 8, 2011 1 comment

Image via Wikipedia

Getting started with the MRP module can be a daunting enterprise, and it is easy  to get lost at it. But actually it is easier than it seems. I will cover the functional elements you need to get started with the MRP module. I will not cover how to do that, it is already covered in the documentation.

In order to start with the MRP module, you just need four pieces of information:

  1. Product information; the first information item you need. Which products you are planning to sell and procure.
  2. Bill of Materials, sometimes called formulas. They are a list of the raw materials, sub-assemblies, intermediate assemblies, sub-components, components, parts and the quantities of each needed to manufacture an end product.
  3. Stock information, pretty much how much inventory you have at hand. If you don’t have this information, you can’t even get started. MRP uses inventory information to determine when and how much to procure.
  4. Master Procurement Schedule; this provides the list of the products you need to procure (either purchase or manufacture) and when you need them. This can be provided by the stock_planning module. Or you could keep an spreadsheet updated with your procurement needs and create the procurement orders from there.

If you are planning on implementing the MRP module, you need to assess the four points I described above. Chances are bill of materials are maintained in paper or spreadsheets. The stock information might be maintained by an information system within the company. But at the end of the day, you will need to assess the quality of the bill of materials. Implementing them will be the longest item in the MRP implementation plan, and you can’t take shortcuts over there. Chances are you will need someone manually checking they are fine, and that you will need to import them manually (which might be the healthiest thing to do).

Well, just wanted to cover some information issues that come up when you are implementing the MRP module.