naming conventions

Discussion in 'General Electronics Chat' started by richertt, Oct 25, 2008.

  1. richertt

    Thread Starter New Member

    Oct 25, 2008
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    I am trying to re-set up a part master in our MRP system. Currently, there are over 40,000 records with descriptions all over the map.

    Is there a standard in the industry for descriptions of components? (Ex. 100 Ohm Resistor: resistor, 100 ohm, 1/4 watt, 5%):confused:
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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    I never heard of one, but that doesn't mean there isn't one.

    You need to have all the significant parameters in the DB. For the resistor you mention, the composition is also significant (carbon, film, wire-wound). Not to mention if it is leaded or surface mount, and if so, the package designator. Makes the DB clunky, but you also need to be able to search on all those parameters. Everything that is in the catalog needs to be in the DB.
     
  3. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    It depends a lot on how your database is organized, indexed, and searched.... and how you store and retrieve the parts. It seems like most-to-least significant descriptor is common for a flat file:

    Resistor, 5%, 1/4 watt, 100 ohm, Ohmite

    But, then again this might be more appropriate for you:

    Resistor, 100 ohm, 1/4 watt, 5%, Ohmite

    One thing I would strongly recommend is "rigidly limiting" who can add new descriptors. I used help convert databases for our new customers, from their old ones to ours. One customer had 13 different spellings for one manufacturer. :(

    Ken
     
  4. steveb

    Senior Member

    Jul 3, 2008
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    I've never seen an industry standard, and MRP systems are generally poor for searching electronics components. From the engineer/technician perspective, we want to be able to find out if our company has a part that meets our needs. But every part-type has difference parameters that are important. Then there are many other detailed specifications, some of which require plots and formulas. The best you can do is have the part number (or data-base fields) specify the most general properties.

    One key thing is to have a readily available source control document (SCD) which is a detailed specification sheet for that part. This SCD is more than the manufacturers data sheet. It also includes an in-house document number and additional information, such as analyses and test information performed in house. Perhaps you can incorporate the SCD number into the part number, or let the SCD number include the part number. At the very least, the MRP system must allow people to easily find the SCD for the part, and allow a procedure for updating the SCD as new information becomes available.

    The real issue becomes apparent now. Even if you succeed in developing a good system, it requires work to maintain. I've never seen a company succeed in developing a good system and then maintain it to the level needed by engineers and technicians. It is time consuming and costly. It's also time consuming and costly to not do it correctly, but you know how it goes. Consequently, I've never heard technical people speak well of MRP systems. I mean that literally; never, not once.

    Maybe someone here can change my negative view of this situation. However, I do applaud you for trying, and I hope you succeed where others have failed.
     
  5. SgtWookie

    Expert

    Jul 17, 2007
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    This is a huge problem indeed.

    I was put on a "preferred parts list" commitee in the late 1980's/early 1990's, and it was nuts.

    You have my sympathy. No, I don't have an answer.

    KMoffet's proposal is flawed; the description should never contain a vendor.

    But the order of parameters I somewhat agree with.

    This isn't something I'm willing to do for free.
     
  6. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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  7. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    I suspect there is not a consensus on that, except maybe in the military. I have been on standards committees too, and vendor identification can be important. A lot of National Semiconductor datasheets and application notes specify specify vendor(s), like for example, electrolytic capacitors for its power supplies.

    Sure, complete specifications might be written, but it is simpler and more reproducible to give the manufacturer's identification. I think you even pointed out once the many different package sizes that exist for nominally similar 8-pin SOIC chips.

    John
     
  8. shreko

    New Member

    Oct 25, 2008
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    I have built an ERP/MRP (metal fab, machinery) from scratch for the company where I work and its been in use for almost 10 years, constantly evolving and changing. The secret is: LISTEN the users of the system how they want it to be. Make small increments/ changes and then step back and let it settle with the users, then go on the next step. Act quickly on their request to change something for better
     
  9. steveb

    Senior Member

    Jul 3, 2008
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    Wow! Management actually listening to people. What a novel concept. ;) Seriously though, I think you are right. A big part of the problem is that people complain, but then don't act to make changes. If you implement a good system, follow the procedures diligently and act on problems quickly, you will do better than most.

    Still, I wonder if metal fab, machinery has the same issues as electronics parts. Many people feel that the type of part doesn't matter. Business people often talk about the "widget" and assume that all things are equivalent. But, I've always felt that electronic parts have many more detailed specifications, plots and formulas. And worse still, there are properties that aren't even captured adequately by specifications, so the part has to be validated by the engineer with detailed testing in the specific application.

    I'm not sure. Maybe I just have an ignorance of the details of other fields.
     
    Last edited: Oct 26, 2008
  10. steveb

    Senior Member

    Jul 3, 2008
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    Ken, you are justified in venting. This is a HUGE problem in engineering product development. I've done postmortem analysis (as I expect many of us here have) on these types of disasters. These problems can cost millions of dollars and even put a company out of business. The two most common causes are purchasing, as you mention, and then parts becoming obsolete.

    The engineer bears some responsibility here, assuming he/she is consulted in the process. What happens is the new part is accepted without adequate testing. The basic specs are compared and are assumed to be equivalent. Most of us here understand that specifications do not tell the whole story.
     
  11. John Luciani

    Active Member

    Apr 3, 2007
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    I have not seen an industry standard on this. If you find one or find information that
    is not proprietary please post a link or email me a link. I am also working on
    a database, table structures and a variety of scripts to populate and
    maintain the database.

    It is a mistake to put manufacturer in the part description field. Adding multiple manufacturers will force you add to add multiple records for identical parts.
    In a separate table you will have a record that maps you internal part number (PN) to a manufacturer (MFG) and manufacturer part number (MFG_PN). In another table you
    will map MFG/MFG_PN to a vendor and vendor part number.

    These tables should be under documentation control. Purchasing should not be allowed
    to substitute an unapproved part for an approved part. If purchasing finds a preferable part then approval documentation should be generated. Representatives from Engineering,
    Manufacturing and Quality need to sign off.

    If purchasing is substituting unapproved parts it is failure of management. Management
    is responsible for putting the appropriate systems in place to insure quality.
    With the proper systems in place the Purchasing department can help reduce product
    cost, decrease time-to-market and improve product quality.

    For the naming specification I am thinking of adapting the IPC-7351
    footprint naming specification. I start with some of the IPC-7351 component
    category tags and add in the missing component types. The categories
    CAP, RES, IND, DIO, LED, BAT, etc. would work. To add sub-categories I would add suffixes.

    For example a 330pf 1% X7R ceramic cap in an 0805 package could be
    CAP_X7R-331-102-0805

    A few other caps --- CAP_NPO, CAP_AE (aluminum electrolytic)
    Cap arrays --- CAPCAV, CAPCAX, CAPCAF

    For ICs maybe IC_AMP, IC_LDO, IC_74LVC138, etc. Some sort of package
    suffix convention is needed.

    (* jcl *)
     
  12. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    Whether the vendor/brand should be in the description field depends on how many fields there are. I agree that if one has a field for vendor/brand then it is best to keep vendor out of the description field, so long as they are linked.

    The issue that most of us have been sensitized to is that a seemingly generic description -- whether it be a capacitor, resistor, or pipet tip -- does not necessarily describe a generic and interchangeable part.

    The point you make about controls is excellent:

    If only that were followed, and those in material management/supply chain would lose a body part when it was violated! Unfortunately, the pain for such "oversights" inevitably falls on others.

    John
     
  13. John Luciani

    Active Member

    Apr 3, 2007
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    Since the OP is setting up the MRP system hopefully he will setup the necessary documentation controls as well (ECO, closed-loop corrective actions).

    At the last company I worked for purchasing was included in the design process.
    The purchasing manager was at the design review meetings. Critical specifications
    were identified and the purchasing manager would work to procure components
    at the lowest cost, highest quality and quickest turn-around. When there were trade-offs
    purchasing would suggest alternatives. Engineering and Manufacturing would have to sign-off on the changes.

    It seems that management accountability has gone out of fashion these days especially
    on Wall Street ;-)

    (* jcl *)
     
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