Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Do Design Engineers know what they're doing?

  1. May 3, 2005 #1
    To start off I'm a Stationary/Operating/Power engineer, what I like to call a practical engineer. I'm the guy that when you walk into the boiler room or engine room is sitting there having a coffee and donut, reading a book. Unless I'm fixing something.

    My pet peeve is designers who come up with these "wonderful","never needs/low maintenance" machines/systems etc. Come on! Get real! Have any of them ever actually had to work on these things? ie:teardown and rebuild. Do they have any practical experience at all? I don't mean building models, I mean actually doing the maintenance/repair work on real equipment. If it takes 3 hours to remove a bolt because some twit didn't allow for the swing of a ratchet, then there is something wrong. If I have to shut down an entire plant just to do a simple twenty minute repair or maintenance item, it is rather costly. Yes, I know, the bean counters are also part of the problem. Low bid equals high maintenance/replacement costs. But why not explain that factor to them?
    I've nothing against higher learning, the why of things rather than the how. But I feel that engineers must also learn the how, the practical side of things.
    KISS
     
  2. jcsd
  3. May 3, 2005 #2

    Q_Goest

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Keep It Simple Stupid!

    I'll drink to that. For any machine I design, I'm the first one to assemble and test it, train others, etc... I've found more than a few times that the machine I designed could have been improved by making it easier to assemble, test, or maintain. Engineers need to get their hands dirty, though many times that's difficult due to unions that forbid non-union (ie: engineers) from working on things.
     
  4. May 3, 2005 #3

    minger

    User Avatar
    Science Advisor

    I'll drink to that. Although this needs to be quick before I start into an anti-union rant.

    Simply put, yes you are correct.
     
  5. May 3, 2005 #4

    Integral

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Oh the tales I can tell! To their credit, there are good and bad in every field. Having been a technician (in the US it is a technician, who is sitting reading a book, with coffee and donut until something breaks) for 30+ years I have seen a lot of bad design and a few good designs. The irony of the situation, the more accessible and easier to work on a tool is, the less likely it is to need to be worked on!
     
  6. May 3, 2005 #5

    cronxeh

    User Avatar
    Gold Member

    as they say it, if you can design it better - do so, patent it, and put the s.o.b who designed the obsolete machine out of business, but dont sit there complaining about it
     
  7. May 3, 2005 #6

    FredGarvin

    User Avatar
    Science Advisor

    That is the absolute truth. I firmly believe that an engineer that doesn't turn a wrench doesn't deserve to design anything. OK that's a bit harsh, but sometimes it does feel like that. I get very annoyed with engineers that feel they don't have to leave the comfort of their desk.

    That being said, there are stupid mistakes and then there are tradeoffs. A designer has a lot of balls to juggle and you are not going to please everyone at once (woo hoo! a double cliche!). I would estimate that more times than not, when a technician has complained about a poor design (in their eyes) there was supporting reasoning why it was done the way it was.
     
  8. May 3, 2005 #7

    brewnog

    User Avatar
    Science Advisor
    Gold Member

    I reckon half the guys on my course have never even held a spanner.

    This is why I'm always hesitant to suggest that you don't need hands-on experience when thinking about applying for an engineering degree. While you can probably do the degree with no practical knowledge whatsoever, your skills are pretty wasted if you can't design a product which can be used (and yes, maintenance/repair is an important part of use).

    Admittedly, it's often tough providing a trade-off between pleasing both the bean counters and the end users, but the repair guy doesn't usually feature highly in this consideration, since they're not the ones buying or selling the product.
     
  9. May 3, 2005 #8

    Integral

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    This is all true. The sad part is a tool (or machine ) which is designed with maintainability in mind will have less down time and therefore be more productive in the long run. So the bean counters are being short sighted when they do not look out for the maintenance end. This is the more common approach, cut the up front costs to the bone, without regard (or knowledge of) to the long range effect.
     
  10. May 3, 2005 #9
    I would love an oppurtunity to apprentice to a Stationary/Operating/Power engineer as a learning experience. This is just not possible. I took a black seal (boiler operators license) course. It was a great learning experience. I always try and get the opinions of the people that are going to work on and use the equipment I design.

    Now, speaking as a designer, I've been given projects where mechanical space was not even considered by the architect or the owner. Mechanical space costs an owner money. They are not willing to give up usable living, working, or selling space just to house a boiler or AC unit which will also cost them money in fuel and maintenance. Yet they want redundancy, maintainability, longevity and ease of use. As an example, I was told to design my ductwork in a space so that there was 16' clearance from the bottom of the duct to the finished floor. The architect then placed his steel beams so that their bottom was at 16'-1" ! Yeah, I was given one whole inch to place 30" diameter ducts!
     
  11. May 7, 2005 #10
    All good points. However, I see little or no reason that some of the commonest design flaws, from my point of view, are the fault of designers not thinking about what will need to be done or possible problems that will be incurred. Instances from my experience:
    1)No washers on motor mounts which pass through sheet steel.
    2)Adjustment points which are inaccessable, or accessable with great difficulty.
    3)Piping which runs so close together that you can' t get wrenches on it.
    4)Hidden valves and gauges.
    5)Lack of drainage or pitch on surfaces where water may collect.
    6) Lack of communication between all involved, while your part is designed properly it conflicts with someone else's part of the project.
    7)Thinking efficient means low initial cost rather than low downtime/operating costs.

    The lazy man invented the wheel.
     
  12. May 8, 2005 #11

    FredGarvin

    User Avatar
    Science Advisor

    You have very good points with the failings of a design. Stupid mistakes such as wrench clearances and hidden components are just plain poor design. One does get that rare occasion where they are backed into a corner when placement of a component has to be in a "less than optimal location." Usually if that happens, special tooling or some kind of workaround for installers/maintainers is required.

    Your #6, in my opinion, actually falls with the design management. That is their purpose in life, along with watching the money, and to make sure the integration of all components goes smoothly. In very large projects it has been my experience that designers can not follow all of the design criteria by themselves and must be constantly fed updates somehow. In the modern design world, the buzz word is "collaboration" and is big business for companies that can tout the easy and real time updating of all people involved in a design.

    #7 I think should include a caveat that sometimes, the higher up front costs are more than worth it if the running costs of a system are reduced. Unfortunately, as long as there are managers that have no engineering/technical backgrounds, this is a tough fight to fight.
     
  13. May 8, 2005 #12

    brewnog

    User Avatar
    Science Advisor
    Gold Member

    I think issues 2, 3 and 6 (and to some extent all the others) are becoming less problematic as companies switch from practicing sequential design, and start using concurrent design processes. However, many products (especially large machines, plant, anything with a long design life) were designed before these measures started to become commonplace, and as a result the maintenance problems are still present.
     
  14. May 10, 2005 #13
    Always obey the law

    Universal Laws for Naive Engineers
    Law #1: In any calculation, any error which can creep in will do so.
    Law #2: Any error in any calculation will be in the direction of most harm.
    Law #3: In any formula, constants (especially those obtained from engineering handbooks) are to be treated as variables.
    Law #4: The best approximation of service conditions in the laboratory will not begin to meet those conditions encountered in actual service.
    Law #5: The most vital dimension on any plan drawing stands the most chance of being omitted.
    Law #6: If only one bid can be secured on any project, the price will be unreasonable.
    Law #7: If a test installation functions perfectly, all subsequent production units will malfunction.
    Law #8: All delivery promises must be multiplied by a factor of 2.0.
    Law #9: Major changes in construction will always be requested after fabrication is nearly complete.
    Law #10: Parts that positively cannot be assembled in improper order will be.
    Law #11: Interchangeable parts won't.
    Law #12: Manufacturer's specifications of performance should be multiplied by a factor of 0.5.
    Law #13: Salespeople's claims for performance should be multiplied by a factor of 0.25.
    Law #14: Installation and Operating Instructions shipped with the device will be promptly discarded by the Receiving Department.
    Law #15: Any device requiring service or adjustment will be the least accessible.
    Law #16: Service conditions as given on specifications will be exceeded.
    Law #17: If more than one person is responsible for a miscalculation, no one will be at fault.
    Law #18: Identical units which test in an identical fashion will not behave in an identical fashion in the field.
    Law #19: If, in engineering practice, a safety factor is sent through the service experience at an ultimate value, an ingenious idiot will promptly calculate a method to exceed said safety factor.
    Law #20: Warranty and guarantee clauses are voided by payment of the invoice.
    Law #21: The rule for engineers: "Change the data to fit the curve."
     
  15. May 10, 2005 #14

    Chronos

    User Avatar
    Science Advisor
    Gold Member
    2015 Award

    Good list, Kleinjahr. Although you omitted a few:
    a] Fatal flaws are only obvious after the final design is submitted.
    b] Inaccessible parts rarely cost more than a few dollars.
    c] Never label a shipping container 'Fragile', or 'This side up'.
    d] Motor windings make the best fuses.
    e] If you can reach it, it ain't broke.
    f] Service kits include triplicates of all required hardware, except the one you just lost.
     
  16. May 12, 2005 #15
    I got the "Laws" off an engineering humour site a couple of years ago. Not sure which it is anymore.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Do Design Engineers know what they're doing?
Loading...