【转帖】parts list - using delete = config mgm

yang686526

parts list - using "delete" + config mgmt.
we have several issues we are attempting to resolve related to the use of "delete" in a parts list for a drawing that has field repairable units.  global drm states non-interchangeability dictates a new p/n.  when is it acceptable to use the word "delete" in the description field of a parts list versus rolling the p/n?  we've been looking for good cm reference material covering this and have come up with none.  interchangeability is discussed here and there but attempting to define when interchangeability is "re-established" is futile.  what is everyone using as cm guides from a practical laymans' standpoint?  also, the use of "nx" next to balloons in an assembly versus "plcs" and "reqd" is popular and we are looking for something to back this up.  any help?
don't recall ever seeing use of delete.  i have seen items given as an either/or option where it didn't affect interchangeability of the completed assembly.  on old manual drawings i've seen items lined through but that isn't really the same.  do you use - numbers in your system?  it allows you to have several similar components/assemblies defined on the same drawing but use of the - number gives each configuration a separate part number.  for assemblies the parts list will have a separate quantity column for each - number.  however, given that it sounds like you've got a lot of what are effectively -1 in the field already but not labeled/tracked with the -1 it may not help.   if in doubt probably a new assembly number is safest.  of course if the new part in the assembly is interchangeable with the old part do you need to track it in the drawing pack other than with the eco anyway?
i believe nx would be the preferred way to the newer asme standards.
that said unless it鈥檚 needed for clarity i prefer to just rely on the quantity in the parts list.
i'm sure you've heard of the phrase "fit, form, and function"?    when the fit, form, or function of a part or assembly has changed to where it is no longer backwards compatible, it is time to issue a new part number.
in assemblies that have a single-level bom, you can replace changed components all day long, but you have to rev the top level part number to inform the world the assembly has changed.  if an assembly has a multi-level bom, you may be able to replace certain sub-assemblies with new part numbers, and not have to change or rev the top level part number.  this is because the system as a whole has not changed.
as for the use of nx for quantity, that is the current standrad over other methods to describe quantities.  my company does not use the nx designator on assembly drawings, but rather uses a parts list on the drawing that defines teh quatity to use.  usually nx is only used on single part drawings to define instances of radii, same sized holes, etc.
art without engineering is dreaming; engineering without art is calculating.
the nx is standard.
the use of "delete" in boms, i have not seen before.
but, "delete" is used in notes. when a note is removed, it is replaced by "delete". it's in a standard, i need to find it and re  
asme y14.5m-1994 section "1.9.5 repetitive features or dimensions. repetitive features or dimensions may be specified by the use of an x in conjunction with a numeral to indicate the 鈥渘umber of places鈥?required. see figs. 1-52 through 1-56. where used with a basic dimen-sion, the x may be placed either inside or outside the basic dimension fiame. see figs. 4-26 and 5-14."
however if you have a bom on the drawing that specifies the qty of parts you should not put nx by the part bubble, as this is double dimensioning, unless it is necessary for clairity.
asme y14.100 section "4.26.6(d) general notes and flagnotes shall be numbered consecutively as a single listing starting with note 1. filling in voids (open spaces) to accommodate deletions is not required. note numbers of deleted notes shall not be reused."
david
thanks david.
chris
solidworks 06 5.1/pdmworks 06
autocad 06
as an end user of part drawings i have to say;
i prefer it when the manufacturer has created a new item number (or item 1a vs. item 1) for a new equivalent p/n whether it follows "form fit function". change the number in the circle/leader and then in the revision notes state item 5 has replaced item 1.  
that way i know;
a) my old part is still valid and;
b) i know what the difference is (e.g. buna vs. teflon, etc.)
c) i know what to order when i run out of it. (maybe i still want buna)
frank "grimey" grimes
you can only trust statistics 90% of the time.
davids second paragraph states why it is customary to use "deleted" in general notes when that note is no longer being used.  having a missing note number looks like a typo.  having a note number without anything behind it looks like a printing error.
that same philosophy goes to find (item) numbers in parts lists.  when you delete a part from the bom, you should not reuse that find number.  instead, use "deleted" as a placeholder.  this is only indirectly related to cm, because cm defines when you can delete a part from an assembly and replace it with another one.
--scott
no worries chris.
david
thanks for the input from everyone.  asme 14.5 reference does cover the "nx" use with all features and dims - thanks. we use global's drm as our guide and 10.11.7.3 explains deleting items and the use of "deleted".  they kind of contracdict themselves with 23.12 (figure 23-5) and the use of "removed" for suffix identifier numbered items.  we are attempting to define this internally from a cm perspective.  if you've got a field repairable item that was deemed to not work due to fit, then the next higher assembly (installation kit) which calls this out must also be changed and on up until interchageability is re-established.  arguements are to use a "deleted" in the parts list of the installation kit calling out the faulty item, add a new find number, and put the new superseding part in.  however, you lose cm control of the original installation drawing configuration...or not?  if i now have two installation kits on the shelf (installation-001) how would you know which one has the good and bad part in it?  these are the fuzzy cm-related rules applied to boms that we are trying to understand.
your erp system (or whatever corporate software you have for managing engineering changes) should provide expiration dates and effectivity dates.  if something is expired, you should do a line clearance to remove the offending components from all locations.
art without engineering is dreaming; engineering without art is calculating.