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FAQ - What is current best practice in part numbering systems?

Current best practice, when using a computer planning system, is for the part number to be non-significant (not descriptive), all numeric and as short as possible to accommodate the largest number of parts envisaged. I have listed below 12 good reasons for this approach.

  1. The part number is entered many times daily. A descriptive part number is re-entering the description which is already held by the system so is double entry and a waste of time and effort.
  2. Descriptive part numbers frequently contain alpha (letters) as well as numeric characters which are in different parts of the key board so cause a disproportionate increase in entry time. If alpha characters are case sensitive the entry time (and aggravation) increases again.
  3. Long part numbers often have to have spacing characters such as hyphens and slashes to make them readable which add to the entry cost.
  4. The more characters that are entered the greater the chance of errors. People can remember up to 6 characters easily (e.g. a telephone number) after that errors increase.
  5. People can guess descriptive part numbers but, because they are close, errors are harder to spot. An error in a non-significant part number is more obvious.
  6. The increasing use of bar codes is another incentive for a short part number. Short bar codes are easier to read and the equipment is cheaper and smaller. Alpha numeric bar codes are over twice the length of numeric bar codes.
  7. All new employees need training in a significant part numbering system. In practice it is rare that everyone really understand the part numbering systems eliminating any advantage. If "wrong" part numbers are created, parts change their use, have multiple use or are inherited from other sites or companies, descriptive part numbers just add to the confusion. Incorrect significance in part numbers is expensive double trouble.
  8. Most systems have part type, classification or codes which are quicker and easier to use to find a type of part and for reports than a descriptive part number. In addition, if there are strict rules for the layout of the description field (see note below), it is more flexible and efficient to find a part using the description field than by using a description coded into the part number.
  9. Even significant part numbers still have to be unique which means adding a non-significant element or adding extensions to the part numbers as and when new product variations are introduced. If the part numbering system is updated, do you update all the old part numbers or allow them to be incorrect?
  10. New significant part numbers have to be created manually whilst non-significant part numbers can be allocated by the system which saves time and administration costs.
  11. If absolutely necessary, sales catalogues can carry on using the old part numbering system. Systems can convert the short, numeric "internal" part number to a sales number for invoicing etc. New products should adopt the new codes from the start (your customers are more interested in your description and specification than your part number). It is also possible to convert suppliers part numbers to the internal number.
  12. Finally, for the dinosaurs who will not change (people do get very attached to their antiquated but familiar part numbering systems) the old part number can be stored in an "external" field for them to use. In practice people very soon get used to the new part numbers.

Some people advocate the use of check digits after the part number. In practice, most planning systems will display the description after a part number has been entered and the vast majority of people will check the description before proceeding. Check digits do not therefore justify the extra digit in planning applications.

Note : sensible and logical use of the description field aids the transition to non-descriptive part numbers. Please see FAQ on part descriptions.

The best education course to help you both decide the best part numbering system for your situation and how to make the change is the Bill of Material course.

Phil Robinson - www.bpic.co.uk
BPIC - your manufacturing planning resource