BOM Management – Have you heard the ticking?

A Bill of Material (BOM) at its core is a very simple concept. It is a list of components needed to manufacture a finished product. So if one was making a pair of spectacles, the BOM may look as follows:

Finished Product	Spectacles	Quantity
Item 1	Right Lens	1
Item 2	Left Lens	1
Item 3	Frame	1
Item 4	Hinge	2

It must be said that understanding how a BOM functions is fundamental to understanding how PLM systems work as this simple list is really at the core of the system. However, simple concepts have a tendency to escalate into very complex subjects. And so it is with a BOM.

One of the complexities associated with a BOM is that an organization usually has a requirement for different types of a BOM in order to define a single product. Most manufacturing companies have at least three types:

1. EBOM (Engineering BOM) is the list of parts that engineers are responsible for and comprises all the components that require some sort of design input
   
2. MBOM (Manufacturing BOM) is the list of parts that are required to actually make the product. This is typically different from EBOM by components that engineering do not specifically design (glue strips, liquid fills etc.). It may also be plant specific.
   
3.  XBOM (Service BOM) is an as built list of parts used in a product that actually made it off the factory floor. This may be different from what was originally specified by the MBOM because of crisis during manufacture. It is important from a customer service perspective.

So the question is – how are your three BOMs authored, edited, maintained and released? Whatever the answer to this question, the outcome is always the same:

1. No BOM – No product
   
2. Wrong BOM – Factory rework or customer dissatisfaction.

An informal survey of small to medium size companies yields surprising results: Excel is the predominant BOM management tool in an engineering environment. Manufacturing BOMs are normally handled by some sort of ERP system and service BOMs are poorly tracked, if at all. This situation is fraught with potential for disaster because of all the manual processes that have to occur before an actual product gets made.

Hence the analogy in the title; BOM management may be a hidden problem that is set to explode in an organization, especially if the products been made become more complex. PLM systems can offer a single organized BOM that represents all the different types in a consistent, controlled manner. Given the potential consequences of the bomb exploding, BOM in PLM should be a priority.

Intelligent Part Numbers – Not so clever

Fundamental to any manufacturing organization, and by extension its PLM system, is the part number. This is a unique identifier for any end component used in a manufacturing process.

Anyone who has dealt with part numbers is familiar with the so called "intelligent part number". To an extent, this is a carryover from the days before sophisticated database systems and fast computers. It involves baking multiple pieces of information into single part number.

For example, consider the fictitious case of the omnipresent widget and assume that it has a Part Number built up as follows:

Initially, the structure of the number seems perfectly logical and in keeping with our concept of what part numbers should look like. However, a more detailed analysis will diagnose some (but not all) potential problems:

1. Clearly, a transition into the 21^st Century is a problem for the first two digits of the number
2. The 1001^th part will not be able to fit
3. The enterprise expands its manufacturing base offshore and wants to introduce country codes

If the intelligent part number is the key attribute in the database, the problem rapidly compounds. This is because it is extremely difficult to change the key attribute in a database once objects have been created and included in multiple relationships.
 

So what is the alternative to intelligent part numbers? The prudent alternative is to set up non-key attributes in the database that contain the information previously baked into the part number. Once this is done, the part number for objects can be a randomly allocated sequence of digits.
 

This may sound counter intuitive but, in the long run, will save a lot of heartache.