Standard Part Number for fastener?

[rlu]

Is there a standard industrial part numbering sytem used for fastener? I'm trying to start a non-significant part numbering system for the company where I work and not sure if I should assign each screws or washers with our new company part number. I understand one should assign company part number for custome parts, but should one also assign one for each fastener too? How about resistors or capacitors for electronics?

Any help is appreciated.

Rlu

 

[swertel]

NO. The only time you want to assign a part number to a fastener is if you need a specific one, such as an Unbrako. And even then, use their part number.

For our fasteners, we usually call out the thread size and pitch as the part number. If is required to meet a certain specification, or grade, then we call that out in the "material and specification" column of the BOM.

--Scott

For some pleasure reading, try FAQ731-376

 

[rlu]

Scott,

Thank you for your respond. Is it a good idea to use vendor's part number in BOM? I'm affair if that perticular vendor is no longer in business and that will create a lot of work to do changes. Do you know if a standard exists that calls out a part number for a perticular screw for example? I heard of standards like ANSI B18. Do you know if this standard call out a unique part number for a particular screw for example?

Similarly, is there a standard part numbering system for electronic parts that has no connection with vendor or manufacturer are?

Richard

 

[swertel]

There is no standard for standard part numbering of fasteners. ASME B18.X only defines thread forms and sizes. That's why we use ".250-20UNC" as the part number in our BOM. The description would be "Socket Head Cap Screw" or "Heavy Hex Bolt." This allows purchasing to buy a fastener that is a ".250-20 SHCS" from any vendor they like. If that fastener has to be grade 8, or meet a MIL-Spec, then we call that out as a specification and purchasing can by any ".250-20 GRD 8 Heavy Hex Bolt" from any vendor they choose.

We use vendor part numbers in our BOM because that is the part that the engineer or designer researched and will satisfy the design requirements. Whether or not material substitutions is allowed is based on company policy. When we use a vendor's part number (which makes ordering easier), we specify the vendor as a flag note. To limit the problem you issued above, a vendor no longer producing that part, we often provide alternate part numbers and vendors in that same flag note. Sole-source items are not good. The only problem is spending the time researching multiple vendors.

For you last question, I don't deal with electronic parts very often. Are you referring to connectors, cables, wires, crimps, splices, resistors?

For items like connectors, you are better off picking a vendor you like and using their part number with a thorough description of what it is you want. For resistors, capacitors, and other components, you can probably just spec out the size: 5 Ohm, 10 microFarad, etc.

--Scott

For some pleasure reading, try FAQ731-376

 

[MouseTrap]

Part Numbers, Part Descriptions, and Part Specifications are three distinct animals - do not ALLOW them to get confused with one another.

Assign a nonsignificant part number to all parts in your system. Numbering systems that attempt to be 'significant' eventually 'fall apart' somewhere along the line.

Many computerized inventory management programs are set up to deal with non-significant part numbers. If in the future, you are to switch inventory management systems, non-significant part numbers are more readily handled in the transition.

One small company I worked for did something similar to what you are attempting, and it became widely accepted within the company that the 'significant' description was the 'part specification', and it took a whole lot of headbanging for them to unlearn their world as they knew it. This was all a shortcut of course, and the company relied on vendors remembering what they 'sold them the last time'. All well and good until there are issues with the vendor.

There are slight nuances, even between standard type hardware and components, that only a SPECIFICATION can define. Do not put your company in the position of being able to mistakingly accept the part number (or the description) as the part specification.

 

[rlu]

Scott, MouseTrap, Thanks for your thoughts. Here is a question: Would it be best to use non-signicant part number (in my case, probably 7 all numerical digits)for designed parts and vendor's part number for standard purchased part such as screws, nut, resistor and capacity? This means that my part list will consist of not only the assigned non significant part numbers but also different vendor's part numbers. How would this affect BOM software?

Richard

 

[MouseTrap]

rlu,

Do yourself (and your company) a favor....
Use chronological numeric (non-significant) part numbers.
A good inventory management program should have the ability to track vendor part numbers and equivelants for parts chosen by the engineers and purchasing.

I can't vouch for your particular BOM software, but a good system should be able to deliver the needed part (or its equivelant) regardless of what the part description states. In fact, a good BOM software does not need to know your part description to accomplish proper inventory control.

Remember, the description is only there as a 'hint' to tell us humans approximately what the part is. The specification will dictate exactly what the part should be.

Regarding using vendors part numbers in your descriptions or as part of your part number, this may work well TODAY, but things change.....vendors go out of business, vendors merge, vendors change part numbers (it does happen), your own purchasing department finds better pricing with another vendor or company. In fact, your purchasing department should always be looking for less expensive sources for all your parts. When such change occurs, the old (vendors)part number becomes useless. Maintaining (vendors) part numbers in your description or part number nomenclature becomes burdensome at best. If your part number or part description is not maintained, old (vendor) part numbers then become incorrect information. If you find that you absolutely have to use a (vendor) part number, use the (vendor) part number in your part specification, but not in your description or as part of your part number.

As a slight aside, and possibly a whole other facet of your dilemna is that I sense that someone or something within your organization is preventing the creation of part specifications.

 

[rlu]

MouseTrap,

Thank you very much for your comment. After a month of searching and hard thinking, I have decided to choose the non-significant part numbering system. For standard parts such as screws or resistors, they each will have a non significant part number assigned to them. I have also decided to seperate part number and drawing number; This way, a part will be able to have multiple documents discribing how it will be manufactured.

Thanks again, my head is now clear and confident to go ahead and introduce this document control to our company.


Richard

 

[Standing]

One thing I wish our company had done was given a type of screw a base number, e.g. 123456 then added the length in 1/16 of an inch. So a ½ inch screw would have been 123456-08. None of our screws are longer than 6 inches. Our screw numbers are spread all over the place. Every time we change the person in charge of giving descriptions the description of the screws change. E.g. Screw, Scr, Scw, Screws and the like, with and with out the comma. They would add a dash after Screw or not which changes the sort. That gives eight different ways to callout a screw. Documentation Control even came up with “rules to live by”. No one followed them.
The same thing can be done for resistors; the ohms would be a dash value. Capacitors would also be a dash value.
My rule would be do not have a person assigning any numbers to parts unless he or she knows what parts are. If you show a person a 10-32 UNC-2B socket head cap screw and ask what it is and they say bolt, assign the job to someone who can tell you what the part is. If they call a resistor a widget hire someone else.


Bradley

 

[JamesJennings]

I'll address your question in two parts: in general, and for your specific situation.

In general:
There is no truely standard fastener part numbering system, but there are a number of fastener part numbering systems that can be used:
- ASME B18.24.x provides part numbering systems that allow the user to build part numbers for nearly any standard fastener based on ASME specifications. The disadvantage of this system is that it requires 20+ digits. ASME is revising this system to use fewer digits, but it still will use more than 15 digits to fully describe a fastener.
- SAE J2295 has a part numbering system for a restricted subset of fastener designs and materials that are commonly used by the maritime community.
- NA 43 and NAS 1347 have part numbering systems for aerospace externally threaded fasteners made to AIA/NAS specifications.
- Military MS drawings, now NASM specifications, have their own part numbering systems for the product that they cover, with each specification having its own system.

Your specific situation:
I agree with Bradley that a part number with an extension indicating length is very useful to both a company's designers and to their customers. Also, making the part numbers all the same length (with leading zeros if necessary), makes it easier to sort and search a database.