advice needed on revision control
advice needed on revision control
(OP)
Hi All
I'm a freelance engineer working on small design projects (typically <100 designed parts). Projects are generally industrial machines that sell in small numbers. With each sale of a machine, design improvements are made.
I'm looking to devise a simple revision control system. I use Autodesk Inventor. No PLM/MRP system.
I understand from other posts on this forum the rules on form/function/fit. For me that will generally mean that whenever I modify a part, it's part number will change. I'm happy with that.
I'm keen to have the part number the same as the (root) drawing number, i.e. if the part is P-100-12301, then the first released revision of the drawing will be P-100-12301-A. (I'm happy to reconsider this if it makes life a lot easier!).
I won't state drawing revision levels on sub-assy and GA drawings, as I understand this is not necessary as revision levels should be interchangeable.
So, when I modify a part that changes form/function/fit I change the part/drawing number. Does this then mean I need to update the BOM's on the sub-assy drawing and the GA? I guess if the part change changes the FFF of the sub-assy then that also needs to change assembly/drawing number, and so on.
Thanks.
I'm a freelance engineer working on small design projects (typically <100 designed parts). Projects are generally industrial machines that sell in small numbers. With each sale of a machine, design improvements are made.
I'm looking to devise a simple revision control system. I use Autodesk Inventor. No PLM/MRP system.
I understand from other posts on this forum the rules on form/function/fit. For me that will generally mean that whenever I modify a part, it's part number will change. I'm happy with that.
I'm keen to have the part number the same as the (root) drawing number, i.e. if the part is P-100-12301, then the first released revision of the drawing will be P-100-12301-A. (I'm happy to reconsider this if it makes life a lot easier!).
I won't state drawing revision levels on sub-assy and GA drawings, as I understand this is not necessary as revision levels should be interchangeable.
So, when I modify a part that changes form/function/fit I change the part/drawing number. Does this then mean I need to update the BOM's on the sub-assy drawing and the GA? I guess if the part change changes the FFF of the sub-assy then that also needs to change assembly/drawing number, and so on.
Thanks.
Hobbs101
Mechanical Design Engineer





RE: advice needed on revision control
Seems like a lot of work. If I have one small change at the part level that affects interoperability at the top level, then all sub-assy drawings have to be modified up the chain. But, I guess there's no way round this from the control point of view! In practice, I guess a number of changes might be included in an update, thereby reducing the number of times the top level number is changed.
Btw, why do you go from -1 to -3, missing out -2?
My intended scheme is
- part number P-100-123-01 (P = part, 100 = project code, 123 = part no. prefix, 01 = part no. suffix)
- drawing number P-100-123-01-A (note, drawings that are at draft for checking/approval will be P-100-123-01-A-01, -02 ...)
- if FFF is changed, then part number will change to P-100-123-02, and drawing to P-100-123-02-A
Is this workable?
A small point, but is the -A referred to as a 'revision' or an 'issue', or indeed a 'version'?!! Is an alphabetic character ok rather than a numeric one?
Hobbs101
Mechanical Design Engineer
RE: advice needed on revision control
Is it not more simple just to up them in issue.
That way your bom structure never changes.
Each time a part chamges up issue the drawing and write a suitable ECN with a unique number and put this beside the drawing issue field on the drawing, that way you will be easily able to tell what the change was.
RE: advice needed on revision control
Hobbs101
Mechanical Design Engineer
RE: advice needed on revision control
The first, as you mentioned, is form/fit/function.
The second, which is often overlooked, is two-way traceability.
If there is a problem in the field, can my customer give me the part or model number (the item they actually purchased) and can I tell exactly which part at which revision went into the item?
If there is a problem with a part, can I tell which items that part was included in?
Feel free to use the attached, so long as proper credit is given.
--Scott
www.wertel.pro
RE: advice needed on revision control
For my work, traceability is absolutely required. I need to know exactly what parts make up an assembly.
What do you think to my intended numbering scheme?
Hobbs101
Mechanical Design Engineer
RE: advice needed on revision control
While in your situation smart numbering scheme may have some advantages, general consensus seems to be dumb numbering schemes end up being better long term. e.g. start with 000-000-001 and work your way up or similar.
Swertel & I are basing this on what the ASME stds e.g. Y14.100 say about it. Some places do use significant revisions but that's not the preferred way of doing it per my understanding of ASME.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: advice needed on revision control
I see no reason not to use 'smart numbering', although I also understand that it's not essential.
Is someone able to comment/answer the queries from my previous post -
Btw, why do you go from -1 to -3, missing out -2?
My intended scheme is
- part number P-100-123-01 (P = part, 100 = project code, 123 = part no. prefix, 01 = part no. suffix)
- drawing number P-100-123-01-A (note, drawings that are at draft for checking/approval will be P-100-123-01-A-01, -02 ...)
- if FFF is changed, then part number will change to P-100-123-02, and drawing to P-100-123-02-A
Is this workable?
A small point, but is the -A referred to as a 'revision' or an 'issue', or indeed a 'version'?!! Is an alphabetic character ok rather than a numeric one?
Hobbs101
Mechanical Design Engineer
RE: advice needed on revision control
So in his case -02 may have been 'Saxe Blue' - he just didn't use it as part of his example.
What you're suggesting may not be a typical application of 'dash' numbers.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: advice needed on revision control
The original part is a -1. The mirror of a -1 is a -2.
If I need to make a completely new, non-interchangeable configuration (aka dash number), it's a -3.
I can't quote from memory the exact specification, but it reads along the lines of
"even number dash configurations are the opposite hand of the preceding odd number dash configurations."
--Scott
www.wertel.pro
RE: advice needed on revision control
If you apply a revision status to a physical item, you essentially created a "new" unique identifier for that physical item. Adding an alpha code at the end of a base number is no different than adding a numeric dash number.
@hobbs101
Changing the part number is the easiest way to guarantee traceability, but not the only way. As my flowchart shows, if you assign serial numbers or lot numbers to your physical items, then your as-built records provide the necessary traceability. That is, if you have as-built records and properly manage effectivity of change. (A can of worms not worth exploring in this thread.)
Numeric or Alpha Revision Characters
It doesn't matter. But, historically, numeric revision identifiers are used to designate pre-production documentation. In other words, when the design is in a prototype or development phase. Alpha characters are used to designate production level drawings. I have even seen a third designation, revisions preceeded by "X" example: X1, X2, X3, or XA, XB, XC.
- Level I - Conceptual (napkin sketches, brainstorming ideas, etc) | Rev 1, 2, 3
- Level II - Development (formal drawings but not all material data or dimensions included, used for first run, test, prototype manufacturing) | Rev XA, XB, XC
- Level III - Production (complete technical data package, all i's dotted, all t's crossed) | Rev A, B, C.
Significant (aka Smart) or Insignificant Part NumbersSome people like to start out initial revisions at "Rev -" or "Rev N/C" (no change). I hate it, computer systems don't like it either.[/li]
It's totally up to you. But you definitely need to have an insignificant portion to any part numbering system or it will soon fail.
My favorite part numbering scheme is to have an intelligent prefix followed by an insignificant sequential number followed by a dash configuration, although the prefix can also be insignificant and sequential.
Example:
Part Number AAA-100000-1 where:
AAA = prefix designating a certain model of a machine, product, tool, or other end-item deliverable.
100000 = the insignificant sequential number.
-1 = the unique configuration identification.
Part number AAA-100000-1 would be defined on drawing AAA-100000^A (I use the caret symbol to delineate the revision).
If I need to make an interchangeable change to AAA-100000-1, I would revise drawing to AAA-100000^B.
If I need to make a noninterchangeable change to AAA-100000-1, I would revise drawing to AAA-100000^C and create AAA-100000-3, still defined on the same drawing. I may have to add another sheet to fully define it. I may have to deal with some pretty labor intensive drafting standards to avoid confusion, but it works. If I AAA-100000 is an assembly drawing with an integral parts list, I may have to play around with how I want to show and balloon the components of AAA-1000000-1 and AAA-100000-3.
By the way, my next prefix for a new machine would be AAB. Thus, insignificant and sequential. But you could make the prefix "smart" by abbreviating the product name, as one example. Just make sure you have a log of prefixes so you don't re-use one.
--Scott
www.wertel.pro
RE: advice needed on revision control
Now I'm confused! I don't understand your favorite part numbering system. I can see that the part number would change from AAA-100000-1 to AAA-100000-3, but I don't understand why the drawing number doesn't go from AAA-100000-1^B to AAA-100000-3^A. The -3 is a new part, so why not create a new drawing?
On your drawing AAA-100000^C, how is part AAA-100000-3 referenced?
Hobbs101
Mechanical Design Engineer
RE: advice needed on revision control
It's completely optional to have a 1:1 relationship between parts and drawings, or a many:1 relationship to show multiple configurations on the same drawing. Whatever works better for you.
Our standard is to show multiple configurations, those with the same base number, on the same drawing. This is very similar to the tabulated drawing technique.
--Scott
www.wertel.pro
RE: advice needed on revision control
Hobbs101
Mechanical Design Engineer
RE: advice needed on revision control
What happens when you want to use the same part on another project/product?
People used to strict adherence to 'all the parts for this machine start with XXX' may be confused by apparantly random 'YYY' & 'RRR' parts showing up in it.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: advice needed on revision control
Hobbs101
Mechanical Design Engineer
RE: advice needed on revision control
Mike Halloran
Pembroke Pines, FL, USA
RE: advice needed on revision control
I'm currently working on projects re-using a whole bunch of legacy parts in new ways - people get confused just by the descriptions let alone if they were tracking intelligent part numbers too.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: advice needed on revision control
There is a prefix for Standard Parts (I always joke that I should make it "STD" because they are shared among many partners).
{Who says engineers don't have a sense of humor.}
1) Create a part that I think is unique to a project, customer, machine, etc. It's assigned the specific prefix.
2) Find out I want to use that part on another project.
3) Re-create the part, but with the standard parts prefix. It's a new part number.
4) Cancel the specific drawing and in the cancellation notice state that it is superseded by the standard part. This creates your breadcrumb trail so I don't have to revise the next level assembly to point to the new standard part. Revising the next level assembly is still a good idea, though.
--Scott
www.wertel.pro
RE: advice needed on revision control
However, maybe I'm missing something.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: advice needed on revision control
The main benefits are 1) human readable information, regardless if integrated into a PDM/PLM system, and 2) most PDM/PLM/ERP systems can easily be configured with naming and numbering rules that handle two insignificant sequential series concatenated into the unique ID.
--Scott
www.wertel.pro
RE: advice needed on revision control
If you are systematically not changing form, fit and function of your parts, then you do not care about the revision number. If you need new parts, you fabricate or build to the latest revision of the drawing. The revisions to the fabrication drawing are corrections of errors, clarification of instructions, or formatting of the drawing. I suppose that a non-functional modification affecting the cost of the part would be okay.
--
JHG
RE: advice needed on revision control
It would, but sometimes non-functional modifications turn out to be, er, functional, or erroneous, so your production records really should tell you what, exactly, went into any given assembly/product, or you will be recalling products that are perfectly okay in order to correct the subset that are not.
Mike Halloran
Pembroke Pines, FL, USA
RE: advice needed on revision control
Peter Truitt
Minnesota
RE: advice needed on revision control
Let's take a soft good like O-Rings as an example.
In my vendor item drawing, I'm going to model the O-Ring at nominal diameter and circularity. But everyone knows an o-ring at installation is squished or stretched. That means for every assembly that I install an o-ring, it will have to have a different representation. By decoupling the part number with the document number, I can cross-reference each of the representations of the o-ring with its original defining part number and document definition.
--Scott
www.wertel.pro
RE: advice needed on revision control
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: advice needed on revision control
Peter Truitt
Minnesota
RE: advice needed on revision control
I was trying to make the relationship in the "digital thread." That which is modeled virtually compared to that which is purchased physically. When filenamining, part naming, and document naming get intertwined, there must be a way to cross-reference each of them. So, in my example, how can I 3D model an O-Ring in a unique configuration, give it a single identifying part number used by any number of other uniquely modeled configurations each with their own unique identification, that all point to a single document that provides the purchasing information for the O-Ring that has its own identification.
I believe this would get off-topic from the original question and should be started into another thread. But it is a very interesting predicament into document, part, and phantom IDs. Relating to the original topic, do I have to revise the document every time I create a new representation of the part?
--Scott
www.wertel.pro
RE: advice needed on revision control
Peter,
When you design in 3D CAD, you need to account for how you will send information to purchasing and production. If you cannot tabulate drawings, you must not generate multiple functional configurations of your models. I am not allowed to tabulate at my site. I feel your pain.
I have had the experience of taking over a design project where someone attached multiple assembly drawings to configurations of one assembly model. This is an unsustainable mess. There is no reason to assume that the model attached to drawing A also affects drawings F and H.
--
JHG
RE: advice needed on revision control