【转帖】manufactured to purchased drawings

yang686526

manufactured to purchased drawings
my company has a hard time keeping the purchasing and manufacturing departments from changing the status of drawings after they are released from eningeering.  they will change a manufactured part to a purchased part, but the drawings never get flaged to change them to vid or scd.  or purchasing will find a new vendor that was not listed on the vid... or will change vendors from what was specified on an scd.
how are other companies managing this issue?
art without engineering is dreaming; engineering without art is calculating.
why do you have drawings for purchased parts?
i have always just used part numbers on the bom's/pl's for purchased parts, and drawings for manufactured parts.
purchasing should never have control to change any engineering drawings.
chris
systems analyst, i.s.
solidworks 06 4.1/pdmworks 06
autocad 06
i am familiar with drawings for purchased parts, namely scds, but am in total agreement with chris as to the legitimacy of any department other than engineering having any change control on drawings.
they don't have control to change the engineering drawings, sorry if that came across in my post, but when they change the status of a component, the drawings never get flagged to be changed to the proper type of drawings (vid/scd).
why have drawings for purchased parts?  we are a manufacturing company, making 90% of our own components.  the other 10% is hardware, bearings, electrical connectors, etc.  due to volume of required parts, or capacity on the manufacturing floor, components are sent outside to be manufactured for us.
art without engineering is dreaming; engineering without art is calculating.
my suggestion is ... if the part is a company standard part (hardware, bearings, electrical connectors, etc.), put scd on the drawing. leave it off everything else. less confusing.
chris
solidworks 06 4.1/pdmworks 06
autocad 06
i may be missing something but if the vendor is manufacturing to your drawing why does it need to be changed from when you are making it?
my last place had a large machine shop but sometimes due to work load parts were outsourced.  they still manufactured to our drawings, essentially the parts were identical regardless if made in house or externally.  
we left it up to manufacturing purchasing which way they wanted to do it.
the standard of drawing was the same even if we knew in advance it would be outsourced.
only if design control were being transferred to the vendor would i expect you to need to make them into a scd/vcd, or am i missing something.  i thought an scd/vcd was only used when you didn't control the design (ie drawings)?
now in terms of changing vendor to an unapproved source this is a quality issue that should be enforced through qualtity audits.  if you have any approvals faa, caa, iso 9001 this should probably be part of you system.
so for custom parts they are not really changing the status, they are changing the sourcing - which i suspect is their justification.
if the part comes in to print, why do you care where it came from?
the "or equal"s for cots parts is another issue.  you need a process to ensure engineering review of any non-qualified suppliers' stuff to ensure that it really is equal.
"equivalent parts" for cots is a different headache, but along the same lines.  i get blind-sided everyweek to approve fais for parts i didn't know were being made outside.
i understood vcd to mean you have no control over the design, and scd meant you have total internal control, at least to the point that the component is critical enough that it must be obtained from source x, not y or z.
vid/vcd... these are used for cots (commerical off the shelf) components.  i'm not too concerned about them.  the scource control drawings are another matter.  purchasing in their all encompassing quest to purchase the cheapest least expensive components will haggle and brow-beat vendors so badly, they will "cut corners" to get our account.
i know my company is crazy is ill-run is disorganized isn't perfect, i just didn't realize it was unique in this case.
art without engineering is dreaming; engineering without art is calculating.
at my last place quality worried about fais.  unless there was a deviation from the design engineering didn't normally get involved.
our copy of asme y14.24 (i think that's right) has gone missing so i can't check but i don't think you have full control with an scd, at least in so much as you don't control the whole drawing pack.  it is typically an outline drawing defining only critical dimensions/requirements and listing approved sources of supply with their details for an item which a vendor supplies but to your specific requirements.
taking an example of a 'black box' specially designed for you an scd would probably define the envelope, mounting/interfaces and inputs/outputs.  it wouldn't detail what was in the box.  this could change completely so long as the dimension and input/output remain constant.
now in terms of deviating from the approved sources of supply for scd this is a quality issue and i would have thought they would deal with it as i posted before.  i'd only expect engineering to get involved if purchasing want to formally qualify a new vendor, and this of course should happen in advance not when the first (or perhaps 2nd or third) batch of parts gets there which it sounds like is happening.
do you have a quality department at your place?  we have one at my current employer but they seem to have defined quality differently from what i was used to in aerospace/defense
outsourcing is a different matter than scds.  enough information should be on the drawing or in the drawing package (procedures, specs) for a competent vendor to produce the item.  as long as the print is met it shouldn't matter if it is made in-house or outsourced.
purchased parts only have to meet the requirements set forth in the scd, and purchasing should have the option of getting the best product for the money, provided the source is approved.
quite often the difference between "purchased" and "manufactured" has nothing to do with engineering at all, but rather with the mrp (manufacturing resource planning) side of the business control software.  i was involved with baan for quite a while, and at one point we had a part that flipped mfg/purch/mfg... 14 times in 3 days because of a squabble in the purchasing group.  for the way that the system was set up at that point, every change of purch/mfg status required an eco (stupid, yes, but that's what happens when business types control the mrp/erp system!!), and thus a revision change as well.  the problem was that you couldn't cut a po for a manufactured part, and you couldn't schedule a purchased part through the shop.  the business group eventually recoded the flags so that purchasing could individually toggle these company-standard parts as needed.  of course, we were literally thousands of wasted eco's down the road before it happened.  it took the engineering manager to finally crunch some numbers on the cost of the repetetive changes and justify the cost of the changes to the software.   
jim sykes, p.eng, gdtp-s
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