Documentation: Part Number System

If you are dealing with a lot of parts, it is best to figure out what type of part number documentation system is best for you and get it implemented as soon as possible. An example to illustrate this point is as follows: Let’s say you have several different manufacturers selected for a 1/8 watt, 0805, 10K Ohm resistor. Each manufacturer has it’s own internal P/N it uses to mark each reel and it typically takes ‘decoder’ documentation from the manufacturer to figure out what this P/N means. The first question that comes to my mind is ‘what P/N do I put on the BOM’? Since each manufacturer P/N is different, how do you account for the other acceptable manufacturer P/Ns? One way to solve this is to create an internal P/N system to control this. In other words, one internal P/N would account for all for the different manufacturer P/Ns (since they are all equivalent in functionality) and allow purchasing to buy any one depending upon cost and lead-time.

A P/N system can go a few different ways:

Serially generated P/Ns with no intelligence
Semi-intelligent P/Ns
Totally intelligent P/Ns

A serially generated P/N is basically just that. The Configuration Management function would just pick the next number in line and assign that number to the new part. So if my P/N scheme was 5 digits long and the last P/N used was 54463, then the next number assigned would be 54464 and so on. There is no built-in intelligence to this scheme other than to just pick the next number in line.

A Semi-intelligent P/N is a system that has some ‘intelligence’ built into the internal P/N itself. For example, my P/N scheme looks like this: 100-63342. The 100 part of the number could represent a family of like parts such as plastic parts or resistors or capacitors etc. The remaining 63342 number could be serially generated.

A totally intelligent P/N is a system that defines all attributes of the number itself. In the case of the example above the 100 represents a family while the 63342 will mean the type of part, the value of that part and tolerance of the part all within its five-digit field.

So what P/N documentation scheme is right for you?

Each of these P/N systems have their own advantages and disadvantages. A serially generated P/N takes a minimal amount of control with basically little documentation to support it. A semi-intelligent takes more control since you have now defined some intelligence into the P/N scheme and someone now has to make sure parts are assigned to the correct family every time. A totally intelligent P/N requires the most control as you will need complete P/N system documentation that defines what each number field means within each distinct position and requires the utmost care when assigning P/Ns to a respective part. The advantage of the totally intelligent system is that you can just look at a P/N and basically know what it is without the need of a database and that they are easily organized and searchable on a spreadsheet.

(Having an MRP/ERP system in place can negate some of the need to add intelligence to your P/N system as you can search on various attributes within the database or perform ‘wildcard’ searches for a specific value or tolerance etc. so keep this in mind when deciding what to do here. It is also very important to note that when inputting new P/Ns into any system, that you create and follow some simple rules to maintain consistency in the title block and description fields).

It is hard to say what is best for your company as each situation is unique but I will state that my personal preference is for some sort of semi-intelligent P/N documentation system. I like being able to just look at a part number and know something about it without having to go to a computer to look it up. Engineers usually like very intelligent numbers because they typically like to know everything about the part at first glance and because some do not have access (by their choice sometimes) to the controlling MRP/ERP system where the information for all parts is maintained.

What ever you choose, pick a documentation system and get all the parts labeled and inventoried (location with total count) so you at least have control on what you have, what you can build with and what you may need to order. Return to Documentation