Part numbers: so simple, what could possibly go wrong? Just ask Ray DeGiorgio, the GM engineer who infamously approved a change to a higher torque switch without changing the part number.
Part numbers are the inevitable result of any manufacturing company. Too often laced with their profusion of spaces, dashes, slashes and sub-codes, they are designed to trip up the unwary. They serve a useful function of separating variations on parts and mean to ensure that the correct part out of many with a similar description is the one that is ordered. Their primary purpose is to remove ambiguity. Does your system:
- Prevent part number confusion?
- Simplify file naming?
- Easily distinguish between similar parts with similar descriptions?
- Detect BOM errors.?
- Allow for part numbering, file naming and part description automation?
If you want your system to thrive under any amount of growth, you will want:
- little to no training needed to generate new part numbers,
- resistance to files being compromised by poor discipline,
- that the same part can be used in different projects without any friction,
- no missing CAD program file references,
- that anyone can easily search for and find a desired part,
- it to handle any logistical situation without choking, and
- cad files to be effortlessly absorbed into future PLM or ERP systems.
Sounds like a fantasy? Well, it is hardly necessary to describe the eye-watering costs to a company using a poor part numbering system, not to mention the huge effort to change to a good part numbering system after thousands of parts are already in the supply chain and in customer's hands. You’ve heard of the Apollo 13 mission where a single un-insulated wire resulted in exploding oxygen bottles, an aborted moon landing and the astronauts barely making it back with their lives. Just keep that story foremost in mind when you design your company’s part numbering system.
Take advantage of our experience working with many companies in all sorts of industries and ponder the following topics:
Part numbers, once created, endure. If the company is successful then fifty years after the manufacture of the components and the publishing of the parts list a junior employee will get a phone call and will be expected to provide a replacement based on the information identified by the part number.
Intelligent Part Number Systems: Often companies like to have a system with an inbuilt code that can be used to determine the part number of an unknown part if the descriptive information and the format is known. They were especially common in the pre-computer days but have no real place in the modern production systems. These “intelligent” part number systems tend to cause pain that outweighs any of the perceived benefits but they seem to take on a life of their own and cannot be easily killed. Why do we here at Ubique insist that this is so bad and unnecessary?
- Difficult to change - Often the scheme does not allow the part number to change when the part undergoes a design change that affects just the inner detail of the part. An improved part that does not fail early will be given the same part number as the obsolete part.
- Off by one-digit error - can result in a plausible looking part being ordered by mistake. If upon final assembly, it is discovered that the box of bolts needed is one size too large or small for the threaded holes the delay can be costly.
- Part Reuse - a manufactured part on a different size or different product line can result in two different part numbers being valid for the same item and will create unnecessary confusion when floor staff constantly sends memos to engineering that the wrong part number for this size of equipment has been specified.
- Ordering of non-existent parts - it possible for an order for a non-existent part to be accepted by sales. An electrical box larger than the maximum size available in the range was specified, quoted and later ordered on a just in time basis. Two weeks after the order was placed the customer was notified that it was not possible to deliver since neither the design nor the tooling existed.
It is worth looking at optimizing or revisiting part numbers at the start of the manufacturing process. As the number of self-similar parts grows, a company relying on descriptive names realizes that the names are becoming the long flowing titles of many a cheap Victorian novel – duplication ensues. Assigning a controller would seem to be needed, but often in companies at this size the desire to hire a person for just this specific task is weak. The result is the creation of an “intelligent” part number system. A set of rules that anyone in the company can follow to generate a unique part number. These systems often have problems with change, especially when there is a change to a part after the initial design has shipped to customers. Eventually, any “intelligent” part numbering system encounters a need its designers did not anticipate. This is the primary reason we advocate the next sequential number system. (Sometimes referred to as sequential random numbers.) In this system, whenever a part number is required, a service supplies the next number.
Sequential Part Number System: Here's what we suggest for a company to use on their cad/part numbering system that will provide minimum friction and maximum flexibility. Imagine the system that will stay exactly the same no matter how large or complicated your product range grows. The next sequential number system is easy to implement, simple to automate and ‘soldier-proof’
- Never run out of part numbers - Some companies have had the sequential numbers grow to seven or eight digits and no one has reported running out of integers yet. (Avoid the urge to back-fill skipped numbers; there is no requirement to use every number). Consequently, the system is scalable.
- An off by one-digit error results in an order for a box of 50, #10-32 screws being replaced by an order for 50, 1.35m slew bearings. A problem, admittedly, but much more likely to be caught by purchasing or the shop floor at an early stage.
- Easy to implement - The next number can be served from a simple webpage, custom SOLIDWORKS® add-in, (see button below) easily incorporated into an inventory system or generated by a service such as SOLIDWORKS® PDM Professional
- File Names created early - Because they can be used early in the design process there is no need for temporary file names or place holders. No missing CAD links to fix. If the design changes then new numbers can always be issued to the new files. There is a very low marginal cost to assigning a part number.
- Tie the part number to the principal drawing file name and not the part file or configuration. When the part is revised and the part number changes it will be easier to do a save as with the drawing file and let PDM manage the model file revisions.
- Multiple uses - One of the benefits of next serial number generation is that the numbers can be used for more than ‘part’ numbers – they can be used for file names, document names, memos, notes, etc.
- Custom Properties - Why try to stuff (maximum) 12 pieces of unique information into the part number/filename when the metadata in each file can hold 50,000? With computers, you can search for, filter for and show any of this information. Embed them anywhere on a drawing sheet.
Power Failure: An argument for the “intelligent” systems is that in the advent of a power failure it is possible to determine what the part is without using a computer. Power failures have become rare events and as a general rule our dependence on electricity so great that most businesses would close early if the power does not return quickly. For these rare cases, the solution is to tie the part number to the main drawing number.
Conclusion: Take care to set up your file and part-numbering system properly at the beginning and the effort will repay itself many times over. If you are dissatisfied with your current system or having troubles preparing files for a PDM vault implementation then we have tools to help, just call 604-986-9696 and ask for Marc.