Manufacturing vs Engineering issues

[james_kashuba]

Good Afternoon Folks,
I have been reading the posts here for a number of years and have finally become a member. As a result, have a few questions for all you guys. Our company in dabbling in the manufacturing realm of our product line. Where we once did just the design and engineering work, now we are pursuing in house manufacturing for some of these items. This has raised a number of questions amongst us concerning our drawings, part numbers, BOMs, revisions, and routing.

From an engineering standpoint we desire to keep the engineering and manufacturing drawings separate, but how do we accomplish this in our PLM system? How do we control revs of one drawing type without affecting the other? Our BOM group is already questioning the part numbers of individually inventoried parts as they go thru their processes. They seem to think that everywhere an item comes to rest it needs to have its own part number to control inventory. Example:
Part comes in sized and in its raw state (P/N), same part gets some holes put in it (P/N), same part gets some additional feathers (P/N), same part gets bent (P/N), same part gets tumbled (P/N), and finally the same part gets panted (P/N).

I disagree with all the part numbers they are trying to assign to an existing part that already has a finished part number. That, I believe, should all be captured in a routing, and those different stages should be on or controlled by manufacturing drawings. Am I incorrect in my view? How does your system or company deal with issue? Is there a document or standard practice that could be helpful during this infant stage?

Thanks ahead of time for your help and advice!
Jim

[Hudson]

Every time you change one drawing, you'll have to change two? Think that through.

[james_kashuba]

Every time you change one drawing, you'll have to change two? Think that through.

I think I understand what you are saying. Depending on how the engineering drawing is being updated it may affect the manufacturing drawing, however, changes to the manufacturing drawing should not affect the engineering drawing - typically speaking. If a bend line on a sheet metal part needs adjustment due to tooling when proving the part, that adjustment or update to the manufacturing print has nothing to do with the engineering print because the engineering side is not necessarily concerned with the process, only the finish product. Hopefully that makes more sense.

What my company wrestles with is how to control two streams of information concerning a single part or item. I'm sure it is an everyday occurrence for some companies, but not for ours. I would rather get this right the first time then make changes mid-drift. So I was really hoping for some sound wisdom would be provided by people with experience in this or at least direct me where to look.

[james_kashuba]

Good Morning Folks,
I have recently posted this in the Manufacturing side, but I haven’t had any helpful responses so I am moving to this side in the hopes of a larger draw pool. I am also adding one of my responses to a fellow member to possibly clarify anything I might missed in the original post.

I have been reading the posts here for a number of years and have finally become a member. As a result, have a few questions for all you guys. Our company in dabbling in the manufacturing realm of our product line. Where we once did just the design and engineering work, now we are pursuing in house manufacturing for some of these items. This has raised a number of questions amongst us concerning our drawings, part numbers, BOMs, revisions, and routing.

From an engineering standpoint we desire to keep the engineering and manufacturing drawings separate, but how do we accomplish this in our PLM system? How do we control revs of one drawing type without affecting the other? Our BOM group is already questioning the part numbers of individually inventoried parts as they go thru their processes. They seem to think that everywhere an item comes to rest it needs to have its own part number to control inventory. Example:
Part comes in sized and in its raw state (P/N), same part gets some holes put in it (P/N), same part gets some additional feathers (P/N), same part gets bent (P/N), same part gets tumbled (P/N), and finally the same part gets panted (P/N).

I disagree with all the part numbers they are trying to assign to an existing part that already has a finished part number. That, I believe, should all be captured in a routing, and those different stages should be on or controlled by manufacturing drawings. Am I incorrect in my view? How does your system or company deal with issue? Is there a document or standard practice that could be helpful during this infant stage?

------------------------- added reply ----------------------
Depending on how the engineering drawing is being updated it may affect the manufacturing drawing, however, changes to the manufacturing drawing should not affect the engineering drawing - typically speaking. If a bend line on a sheet metal part needs adjustment due to tooling when proving the part, that adjustment or update to the manufacturing print has nothing to do with the engineering print because the engineering side is not necessarily concerned with the process, only the finish product. Hopefully that makes more sense.

What my company wrestles with is how to control two streams of information concerning a single part or item. I'm sure it is an everyday occurrence for some companies, but not for ours. I would rather get this right the first time then make changes mid-drift. So I was really hoping some sound wisdom would be provided by people with experience in this or at least direct me where to look.

Thanks ahead of time for your help and advice!
Jim

[Kelly_Bramble]

As an engineering trainer and consultant I always tread carefully on the topic of engineering vs manufacturing drawings.

Best practices are as follows..

An engineering drawing is the end item drawing and is not a manufacturing detail process specification document. The reason for this is that the end item part or assembly can be manufactured in an infinite number of ways.. The end item manufacturing party will build the part using the machinery or people skills that they have however if that machinery changes then the process may change. Also, the part or assembly may be produced in a different capacity manufacturing facility and the best procedure or equipment used to build the end item will be different. Manufacturing personnel are the most logical and capable people to define the manufacturing process, tools, procedures etc.. Not the design engineer.

Therefore;

The drawing should define a part without specifying manufacturing methods. Thus, only the diameter of a hole is given without indicating whether it is to be drilled, reamed, punched, or made by any other operation. However, in those instances where manufacturing, processing, quality assurance, or environmental information is essential to the definition of engineering requirements, it shall be specified on the drawing or in a document referenced on the drawing.

Sometimes it is necessary to specify Nonmandatory processing or manufacturing features, details or dimensions. This data should be identified as “NONMANDATORY (MFG DATA).” Examples of nonmandatory data are processing dimensions that provide for finish allowance, shrink allowance, and other requirements, provided the final dimensions are given on the drawing.
Manufacturing drawings, routing documents, travelers are separate documents and are document controlled as such. These document are normally produced by manufacturing personnel not design engineering. However, just as design engineering personnel engage manufacturing for a document review – it may be a good practice for manufacturing engineering or other to engage design engineering in a review of the manufacturing procedure.

[Kelly_Bramble]

What my company wrestles with is how to control two streams of information concerning a single part or item.

Manufacturing organizations generally have their own document numbering system in place. A documentation project to produce a part or assembly is clearly linked to the engineering drawing part by program numbers, PO, or engineering drawing acronyms.

For an acronym an internal manufacturing organization may append the engineering drawing number as follows:

Engineering Drawing Number: 123456
Traveler: tra123456
Routing: Rt123456
Manufacturing: MAN123456

There are infinite ways to identify separate manufacturing documents and associate with an end item engineering drawing.
To define that an engineering drawing change has occurred we use Change Notices. These are named all sorts of creative names – like ECN (Engineering Change Notice), ECO (Engineering Change Order), ECR (Engineering Change Requirement), etc..

[Hudson]

You are correct. You do not want prints for every stage of manufacturing. It would be difficult to keep all of the changes straight. (That was the point I was trying to make.)

There are some cases where manufacturing processes must be called out on a finished drawing but this should be minimized. Prints should address fit, form and function. If the function requires a specific manufacturing process, say heat treatment, call it out. You may need casting drawings if you create something in a foundry that requires the ability to conduct incoming inspection.

You are probably best served by focusing your efforts on manufacturing instructions. Digital pictures might function quite well in lieu of prints to describe your operations.

[james_kashuba]

thank you both for your input. Kelly, you nailed it with the part numbering schemes. That is the exact way I am trying to get them to go. Do you know of any best practice documentation that could be helpful, especially for the manufacturing side?

Thanks

[Kelly_Bramble]

thank you both for your input. Kelly, you nailed it with the part numbering schemes. That is the exact way I am trying to get them to go. Do you know of any best practice documentation that could be helpful, especially for the manufacturing side?

Thanks

Probably, Global Engineering Documents "Drawing Requirements Manual". It is per. MIL-DTL-31000.