¡¾×ªÌû¡¿value of drawing check

yang686526

value of drawing check
got me thinking.
does anyone have any really good methodology for finding the financial benefits of drawing checking.  or for that matter any examples of amounts saved etc?
research implemeted change orders and what it cost to correct existing parts and documentation.  do this with several "problem" parts, and you should get a good idea of minimum cost per change order.  proper checking should eliminate much of this.
i have heard of a lockheed study regarding what ewh describes, as in average cost per dcn; i don't know what was said in it, but i remember some engineers talking about it. it would have been done sometime in the late 1970's or early 80's... not that htis is any help..
wes c.
------------------------------
no trees were killed in the sending of this message, but a large number of electrons were terribly inconvenienced.
just think about your business process regarding design releases.  i've looked at how many people in my company have to touch a ecn before it is released and it's eye opening.  it's a wonder we stay profitable and it's frustrating because a little forthought could enable us to have a bonus at the end of the year.
best regards,
heckler
sr. mechanical engineer
sw2005 sp 5.0 & pro/e 2001
dell precision 370
p4 3.6 ghz, 1gb ram
xp pro sp2.0
nvidia quadro fx 1400
      o
  _`\(,_
(_)/ (_)
never argue with an idiot. they'll bring you down to their level and beat you with experience every time.
kenat,
   i am pushing for two things where i work.
1.  design checking must be done by a qualified person, in my opinion, an experienced, competent mechanical designer.
2.  design checking is optional, at the discretion of the project manager.
   unfortunately, our checking is mandatory, but it can be done by the secretary's cat.  there is no qa definition of what it means when something is signed off as checked.
   unless your office works on a narrow range of assemblies and parts, you cannot write general rules of how economical checking is.  you can decide on a task by task basis.
   what are the consequences of failure?
   the design checker consumes man-hours and schedule time which could be spent producing new designs and drawings.  if the mistakes they catch cost more than this, the design checking is economical.
   if you can take the parts back to the shop, quickly make corrections and then fix the drawings, there is a good chance design checking does not pay for itself.  if the parts are expense and require long lead times, you had better get it right the first time.  also, there had better not be any safety problems.
   design checking also is an opportunity for an experienced person to get a look at everybody else's work.  if the drawing office is not properly supervised, someone could be producing absolute crap.
                       jhg
all of the big major corporations and the military have a checking process. if you want to do long term business with any of them, you will need to have a system that is similar. a small contract with them probably would not matter.
i worked with a checker that quit. the errors multiplied from some designers and parts were scrapped. we hired an experienced checker, errors greatly reduced. this is for new drawings.
checkers don't make much salary compared to $$ lost and losing contracts because of errors and parts shipped late.
chris
systems analyst, i.s.
solidworks 06 4.1/pdmworks 06
autocad 06
the aberdeen group (sorry, no url) just completed a benchmark report concerning the transition from 2d to 3d.  in it, they listed some costs associated with change orders.
very complex products- $5,886
moderately complex products- $2,021
simple products- $1,492
art without engineering is dreaming; engineering without art is calculating.
and remember the cost of making bad parts if you're on a military is 100% inspection and having a field engineer parked in your qa department.  it can cost big bucks with in lost revenue and some companies (hon) charge your for their fes time
best regards,
heckler
sr. mechanical engineer
sw2005 sp 5.0 & pro/e 2001
dell precision 370
p4 3.6 ghz, 1gb ram
xp pro sp2.0
nvidia quadro fx 1400
      o
  _`\(,_
(_)/ (_)
never argue with an idiot. they'll bring you down to their level and beat you with experience every time.
drawoh, i think you sum it up nicely with your comments
“What are the consequences of failure?�br />
“The design checker consumes man-hours and schedule time which could be spent producing new designs and drawings.  if the mistakes they catch cost more than this, the design checking is economical.â€?br />
however the answer to your question will vary widely depending on many factors.
just some other thoughts.
how good are your designers as with any walk of life there are good and bad and the good make far less mistakes, is it more cost effective to have a bad designer and a checker or a good designer?
how good are your checkers? whilst they will spot some mistakes, how many do they spot?
how much feed back from production does the design department receive? is the same mistake being made over and over with no one being aware of it?
finally does having a checker lead to bad work? if you were a high wire walker would your mind be more focused knowing you did not have a safety net?
i can't see that having a checker will lead to bad work, as the drawing creator (drafter) will still have to make those corrections, and after a couple of times back and forth, the last thing the drafter wants is to revisit that drawing.  if anything, this encourages that it be done right the first time, which in turn encourages the drafter to learn how to do a drawing correctly.
interesting post.
so far we've included:
- drawing checking
- drawing sign-offs
- ecn/eco sign-offs
i'm willing to bet all of us have had to deal with non-value added sign-offs regarding all three.
i am a firm believer in cross-checking work within a design group at a minimum. from my experience, this catches most errors and also provokes discussions within the group.
"finally does having a checker lead to bad work? if you were a high wire walker would your mind be more focused knowing you did not have a safety net?"
ajack1;
  that is the way i see it, if you know there is no check most professionals will step up to the plate and lessen their mistakes..
  i have worked several places without check and the errors that got to the shop floor were about the same as with a check.
  my belief now is to set another qualified engineer down with you and briefly review what you have done and why.
this will show glaring errors and the rest are probably trivial.
i don't know anything but the people that do.
  in most of the companies at which i have worked, the engineers were no better at gd&t than the drafters, sometimes worse.  i once worked for an engineering manager at an aircraft company who rejected a drawing because i had the audacity to suggest a positional tolerance of 0 at mmc (which the design called for).  he thought that "perfection" would be impossible, but obviously didn't understand the gd&t involved.
  mistakes get carried thru to the floor, and have to be lived with.  these mistakes soon become legacy practices.  those who have to create and inspect the parts manage to document acceptable work arounds to what are essentially poor drawings.  having a knowledgeable checker to enforce correct practices eliminates these poor habits and work arounds.
  yes, most professionals will "step up to the plate", but when no one knows the correct action to take, the engineers don't realize how little they actually know about a correctly detailed and toleranced drawing.  
i'm "old school", and we always had a checker go over the project before it was issued, it was the way a normal company operated. then things started getting tricky (i'm talking mid-80's here) there was a down turn in manufacturing and in my field oil production. owner companies looked at ways to reduce their overhead. they did this two ways ...they laid off most of their senior engineering types and keep only afew to ride herd over the new college grads. also they pretty much eliminated their design/drafting staff. the thinking was they could contract any design/drafting out if they needed any. also autocad poked its nose into things, and changes all the rules as to how things were none. so alot of good experienced people left the business. because things were slow at the time, there wasn't much need for alot of quality people then. so all the business management people and h.r. thought they had done a fine job!
...till now! since that time nobody has trained or educated anybody to replace them! ...yes they trained them to run autocad, but nothing else! if you teach someone to drive a car, can you make the conclusion that they could re-build the engine too? ...well big business did! ...and now they are paying for it! *l*
this is a long winded way of saying there is a proper way of doing things, and trying to change that by removing parts of the foundation of the house and seeing if it falls or not is not it. checkers have been an integral part of engineering and construction for alot of years. they have saved alot of headaches and problems, and removing them form the system was an extremely poor move  â€?and that's putting it mildly!)  
the quicker “weâ€?turn back the clock and return to a proper system the quicker we dig ourselves out of this hole! …Yes we can still use autocad ( i never did like my lettering anyway!*g*)    …My $0.02!   â€¦Mark
i agree with ewh and 11echo, except i prefer solidworks over acad.
as i had written in other threads, we have got lazier, some don't care, and work has been cut/outsourced to save $$. from my experience, companies are switching to 3d cad and laying off drafters, designers and checkers. just because everything has gone 3d, doesn't mean we don't need checkers.
i tell the engineers and managers, when you were in college, didn't you have somebody else read your papers to check for errors? the same goes for drawings.
chris
systems analyst, i.s.
solidworks 06 4.1/pdmworks 06
autocad 06
interesting.
i started this thread just seeing if anyone had any really good methods, figures or even, though i’m loathed to admit it, sound bites that justify having drawings go through drawing check.  thanks to those that came up with ideas on this.
it seems to have turned into a discussion of whether or not checking is worthwhile.
my opinion, for what little it’s worth, is that drawing check is invaluable; and if you have high enough thru-put to justify it then having dedicated checking staff is the best option.  
as such my post was more to find ways of justifying it to management, especially those who don’t know the sharp end of a cad package from pac man.
i guess i didn’t make it clear, or perhaps it’s just a logical continuation of the thought process, i went into it with the pre conceived notion that drawing was invaluable and that i just wanted to justify it, others have reversed the question and asked if it’s even worthwhile and perhaps it can’t be justified.
quote:
finally does having a checker lead to bad work? if you were a high wire walker would your mind be more focused knowing you did not have a safety net?
does having traffic police lead to bad driving?  presumably if they all passed their driving test then they know better and don’t need checking up on.  at the very least surely traffic enforcement don’t need to worry about checking on truck & taxi drivers as they are ‘professionalsâ€?and so will presumably step up to the plate?
as an extension of this, does having law enforcement lead to lawlessness?
there is a slightly trite, though arguably true saying i’ve heard on this subject.
quote:
people do not do what you expect, people do what you inspect.
the best engineers and drafters i’ve worked with made mistakes, perhaps fewer in number, but mistakes none the less.  if most publishing houses can justify proof readers then is it too much to expect the same for drawings?
there is no point having drawing standards and conventions if no one enforces them.  if you abandon conventions then just think how long it would take to detail a drawing in such a way that it cannot be misinterpreted.
just my thoughts, probably not worth the paper they’re written onj.
i doubt many would dispute that having a checker improves things the question is does it make economical sense?
even if drawings are checked things will get missed so do you have a checker to check the checker and then someone else to check their work, how far do you go for the quest of perfection? in some cases probably a long way a flight to mars for example will cost many millions with no simple get out if things go wrong, it may well be worth having many levels of checking. if however you are producing paper clips that sell for 50 cents for 500 it is far less likely to make economical sense.
whether it makes sense for a particular company or product depends on so many variables that i doubt there is a fits all answer.
going back to focusing your mind, if you replaced a few of the air bags in your car with metal spikes would it make you drive more carefully? i am not suggesting that it would make driving safer, but it would make you a more careful driver, well it would me at least.
agreed, it does depend on the product.  paper clips shouldn't need much checking.  the machine producing them should be more fully checked.  anything involving advanced gd&t should be thoroughly checked, as mistakes of this type can cause considerable cost increases.
i would hope it wouldn't take a checker long to review the drawing of a paper clip.
the $30 worth or so of his time is well spent if it prevents production of several thousand non functioning paper clips.  which with the added cost of modifying the machine producing them could be surprisingly expensive.
the cost of drawing check on 'simple' parts is reduced because it wont take as long to check.
certainly i'm not proposing that every small design house that churns out a few drawings should have a dedicated checker but the concept of having drawings checked is i believe important.
the one time i can think of that it's perhaps least important is for any low volume, low cost items, especially if they can be easily modified.  i'm thinking some assembly & tooling fixtures.
personally i found the grief (mostly good hearted leg pulling but annoying none the less) i used to get from the checker & other senior designers for producing bad drawings and the desire to get one through without red pencil more than adequately focused my mind
certainly you need to look at the economics of it which was the reason for my initial post, my concern is that it's very difficult to accurately estimate those costs.  tracking ecos is a good start but what about scrapped parts, re-work time, unnecessarily difficult to manufacture parts, or even worse scrapped/delayed parts which then prevent a $1500000 tool shipping on time which causes the major customer to look elsewhere for equipment in the future etc.  no checking process can guarantee catching all the mistakes but not having one is asking for trouble.
ajack1,
imo, the small seemingly simple drawings are often the ones we need to check the most. they are the ones that we are most likly to cut and paste and rush through. i find that i get more phone calls from fabricators about the simple drawings that our engineers sent out without a check(and consiquently have missing dimensions) than the complex drawings. usually if i get a call about a complex drawing it is just to make certain that they understood something, rather than "what was this dimension supposed to be". i would rather have someone look at my drawing to verify that i hadn't overlooked something and take an extra hour than to hold up production for days because my parts got bumped because they had to track down a dimension.
  we have had a chance of having the checker design an assy tool. after designing it and putting together the check package, we gave him the job to check. the mistakes were basically the same we all make, tolerance issues, typos calcs and incomplete information.
  the lesson learned is that any one of a professional team would be able to repeat this process.
  as of now we no longer use drawings, but do have a model base definition check list and that is first checked by the designer, then a checker will go down the list.
  this has taken away some of the subjective checking that we had with a check group, and made them specific adjective points.
i don't know anything but the people that do.
if you had the checker design it and then check it, you end up with the same problems of having everyone check their own work.
mbd does do away with much of the subjective "style" checking, but the gd&t and assembly method is still critical.
again ... i agree with ewh
chris
systems analyst, i.s.
solidworks 06 4.1/pdmworks 06
autocad 06
posting in the eng-tips forums is a member-only feature.

  
unauthorized reproduction or linking forbidden without express written permission.
research implemeted change orders and what it cost to correct existing parts and documentation.  do this with several "problem" parts, and you should get a good idea of minimum cost per change order.  proper checking should eliminate much of this.
i have heard of a lockheed study regarding what ewh describes, as in average cost per dcn; i don't know what was said in it, but i re  
just think about your business process regarding design releases.  i've looked at how many people in my company have to touch a ecn before it is released and it's eye opening.  it's a wonder we stay profitable and it's frustrating because a little forthought could enable us to have a bonus at the end of the year.
best regards,
heckler
sr. mechanical engineer
sw2005 sp 5.0 & pro/e 2001
dell precision 370
p4 3.6 ghz, 1gb ram
xp pro sp2.0
nvidia quadro fx 1400
      o
  _`\(,_
(_)/ (_)
never argue with an idiot. they'll bring you down to their level and beat you with experience every time.
kenat,
   i am pushing for two things where i work.
1.  design checking must be done by a qualified person, in my opinion, an experienced, competent mechanical designer.
2.  design checking is optional, at the discretion of the project manager.
   unfortunately, our checking is mandatory, but it can be done by the secretary's cat.  there is no qa definition of what it means when something is signed off as checked.
   unless your office works on a narrow range of assemblies and parts, you cannot write general rules of how economical checking is.  you can decide on a task by task basis.
   what are the consequences of failure?
   the design checker consumes man-hours and schedule time which could be spent producing new designs and drawings.  if the mistakes they catch cost more than this, the design checking is economical.
   if you can take the parts back to the shop, quickly make corrections and then fix the drawings, there is a good chance design checking does not pay for itself.  if the parts are expense and require long lead times, you had better get it right the first time.  also, there had better not be any safety problems.
   design checking also is an opportunity for an experienced person to get a look at everybody else's work.  if the drawing office is not properly supervised, someone could be producing absolute crap.
                       jhg
all of the big major corporations and the military have a checking process. if you want to do long term business with any of them, you will need to have a system that is similar. a small contract with them probably would not matter.
i worked with a checker that quit. the errors multiplied from some designers and parts were scrapped. we hired an experienced checker, errors greatly reduced. this is for new drawings.
checkers don't make much salary compared to $$ lost and losing contracts because of errors and parts shipped late.
chris
systems analyst, i.s.
solidworks 06 4.1/pdmworks 06
autocad 06
the aberdeen group (sorry, no url) just completed a benchmark report concerning the transition from 2d to 3d.  in it, they listed some costs associated with change orders.
very complex products- $5,886
moderately complex products- $2,021
simple products- $1,492
art without engineering is dreaming; engineering without art is calculating.
and re  
drawoh, i think you sum it up nicely with your comments
“What are the consequences of failure?�br />
“The design checker consumes man-hours and schedule time which could be spent producing new designs and drawings.  if the mistakes they catch cost more than this, the design checking is economical.â€?br />
however the answer to your question will vary widely depending on many factors.
just some other thoughts.
how good are your designers as with any walk of life there are good and bad and the good make far less mistakes, is it more cost effective to have a bad designer and a checker or a good designer?
how good are your checkers? whilst they will spot some mistakes, how many do they spot?
how much feed back from production does the design department receive? is the same mistake being made over and over with no one being aware of it?
finally does having a checker lead to bad work? if you were a high wire walker would your mind be more focused knowing you did not have a safety net?
i can't see that having a checker will lead to bad work, as the drawing creator (drafter) will still have to make those corrections, and after a couple of times back and forth, the last thing the drafter wants is to revisit that drawing.  if anything, this encourages that it be done right the first time, which in turn encourages the drafter to learn how to do a drawing correctly.
interesting post.
so far we've included:
- drawing checking
- drawing sign-offs
- ecn/eco sign-offs
i'm willing to bet all of us have had to deal with non-value added sign-offs regarding all three.
i am a firm believer in cross-checking work within a design group at a minimum. from my experience, this catches most errors and also provokes discussions within the group.