A part number
is a unique identifier
of a part used in a particular industry. Its purpose is to simplify referencing to that part. A part number unambiguously defines a part within a single manufacturer.
For example, when specifying a screw, it is easier to refer to "HSC0424PP" than saying "Hardware, screw, machine, 4-40, 3/4" long, panhead, Phillips".
User Part Numbers vs. Manufacturer Part Numbers (MPN)
using a part
will often use a different part number than the various manufacturers
of that part do.
For example, when referring to a "Hardware, screw, machine, 4-40, 3/4" long, panhead, Phillips":
- Manufacturer A uses part number "4-40-3/4"-pan-phil",
- Manufacturer B uses part number "100-440-0.750-3434-A".
- Manufacturer C uses part number "TSR-1002".
The business using such a screw may buy screws from any of those manufacturer, because they are identical. To identify such screws, the user doesn't want to use any of those manufacturer's part numbers, because
- it would imply that one manufacturer is acceptable and the other ones aren't, and,
- it wishes to use a consistent format for the part numbers of all of the parts it uses.
Therefore, the user devises its own part numbering system.
In such a system, the user may use the part number "HSC0424PP" for that screw.
Significant vs. non-significant part numbers
In general, there are two types of part numbering systems
(a.k.a.: Intelligent) and non-significant (a.k.a.: non-Intelligent).
- In a Significant Part Numbering System, the part numbers are assigned intelligently and are an indication of salient characteristics of the component. For example, a screw may have the part number "HSC0424PP".
- In a Non-Significant Part Numbering System, part numbers are assigned in some other fashion, such as sequentially. For example, a screw may have the part number "1002".
Significant part numbering systems are easier to use, though a new part number is harder to assign.