Dear Abhishek

There are several reasons for a product to have different BOM structures:

Different recipes to achieve the same result (final product)

Different sub-assemblies

Different routings and in consequence different parts

Etc.

Normally the different structures are so called product variants.  

Once a product is brought into the market, it has a unique identification and drawing reference. All sub assemblies and components are referred to in the product drawing, so there is no way for any product which is subject to engineering control, to have have more than one BOM concurrently.  A given version of the product can have a different BOM then earlier versions though, and that is consistent with engineering controls.

I'll make it simple with a example. Suppose you are assembling a mobile smart phone, so you will have sub assemblies for touchscreen, circuit board etc. In final process you will assemble it into a phone. In such a case your BOM will change only if you start outsourcing may be touchscreen . If you keep same routing, same process, same product and same system. There is no possibility to have a different BOM. BOM's are usually updated when parts manufactured are now being outsourced, Change in process, change in product or change in routing. In short if all the parameters are constant a BOM cannot change.

I'd suggest you to go through the first chapters of the book

Vollman, T.E.; Berry, W.L.; Whybark, D.C. "Manufacturing planning and control systems", McGraw-Hill. It gives you a lot of information answering to your question. Regards

Suppose if a part can be sourced from multiple vendors, does it mean BOM routing is different?

Strictly speaking as per rules of engineering control, the answer is no.

You will find this in the book suggested by Dr. Romagnoli.  

This question arises because of the way work flow is configured in an ERP or equivalent.

In SAP the BOM is independent of the vendors and hence the same part can come from different vendors.  Most of the ERP configured for manufacturing are like this.

However, some work flow software used in IT industries and defence industries, recognize that the component coming from different vendors are essentially different, and hence need to be given unique part numbers and hence the need for  multiple BOM. 

Yes, it's completely possible, because components or sub-components can be different...

A PRODUCT CAN BE MADE IN MANY WAYS AND ALL POSSIBLE WAYS WILL HAVE DIFFERENT BILL OF MATERIALS. HENCE, YES, AT ANY GIVEN TIME, ANY PRODUCT WILL HAVE MULTIPLE BILL OF MATERIALS. IT IS UPTO US TO CHOOSE THE BEST POSSIBLE BILL OF MATERIALS FOR THE PRODUCT MEETING OUR REQUIREMENTS.

REGARDS.

SEKAR GOPAL.

Dear Abhisheck,

here I have listed some reasons why you can have different BOMs for the same product, with some explanation.

First of all let's consider the fact that you can have different boms for different functions. For instancem an engineering BOM can differ from a manufacturing BOM, in trhat engineering is analytical (you start from general, and go down to particular) while manufacturing tends to be synthetic (you start from components and join them to get a finished product). Likewise, a service BOM can differ from manufacturing BOM and engineering BOM alike.

Moreover, any manufacturing BOM can evolve in time, due to different engineering versions, restylings, improvements, and so on. Therefore each BOM has a pahe-in date in which the new version will simultaneously be phased-in. Therefore, at any given moment a single product could have one active BOM, one or more phased-out BOMs and one or more BOMs that have not yet been phased-in.

Furthermore, because you can make the same product in various ways, any active BOM can come in various, alternative versions. For instance, component A and B could be two alternatives, so you have 2 BOMS, the former specycying A and the latter specyfying B. Or, you could have two fashions of assemblying a product starting from the same components: in the former you just joint all components at a time a obtain the final product: therefore you will have a 3 level BOM; following the latter you could firstly assemble some subgroups, and then join the subgroups to form the final product: thereore in this case you will have a 3 levels BOM.

But maybe the most frequent reason of all to have different BOMs for the same product could be to take into consideration variants. For instance, a car could come with different colours, or a different optionals mix; a shoue could come in different sizes; etc. All of these variants can be taken into consideration by means of various techniques, that lead to different or parametric BOMs for the same product.

Yes, it is possible. For example, if you are using different manufacturing methods for the same component.

However, once the processes are decided then it is not practiced for better engineering control.