×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Bill of materials pt # verses Assembly drawing pt #

Bill of materials pt # verses Assembly drawing pt #

Bill of materials pt # verses Assembly drawing pt #

(OP)
Bill of materials part number verses Assembly drawing part number: should they have the same part number, or different?

At my company, we’ve had some disagreement on the above topic.  I would like to get some outside options on how to handle this.  Currently, we have a program that helps us structure our bills of materials.  We’ve been assigning the same part number to our BOM’s and assembly drawings.  Both BOM and assembly drawing have revision control.  Using this configuration, should the BOM and assembly drawing always have the same revision letter?   Should the BOM have a different number entirely, so that if a purchased component is changed it won’t affect the assembly drawing revision?  Any options would be greatly appreciated.

RE: Bill of materials pt # verses Assembly drawing pt #

The dwg and BOM don't have to have the same rev level.  They can share the same basic drawing number, but need to be differentiated somehow, such as "1234-56" for the dwg and "PL1234-56" for the BOM.

RE: Bill of materials pt # verses Assembly drawing pt #

(OP)
Thanks for the reply.  You methodolgy is exactly what I was thinking of implimenting.

RE: Bill of materials pt # verses Assembly drawing pt #

Agree with ewh.

At my last place we didn't use the BOM to define the build standard of the item.  

We had what was called a drawing list for top level assemblies.  This was a list of all the drawings with their rev.  It was maintained as part of the drawing pack.  It had the same number as the drawing it related to but with DL prefix when required.  Parts without a drawing were only listed on the relevant part list.

The drawing list did not have to have the same rev as the top level drawing it related to.  It had its own rev and it was this rev that controlled what the latest build standard of the item was.

Manufacturing created the BOM based on the Drawing list and all assembly & subassembly drawing parts lists there on.

At my current place the BOM is the controlling document as regards the rev level of all drawings and is kept at the same rev as the drawing, when there is one.  Historically here many higher level assemblies are only a BOM - no drawings, it causes problems and we are trying to correct it.

RE: Bill of materials pt # verses Assembly drawing pt #

Drawing numbers and part numbers should be different but in general are similar enough that it is easy to find the drawing/file if you know the part number.  Another reason that part numbers and drawing numbers shouldn't be the same is because many times a drawing will show more than one assembly, left hand and right hand, for example.  Or maybe it will show two or more very similar assemblies.

In my opinion the drawing and part should have the same rev levels in order to keep track of corresponding parts lists and associated drawings.  When a drawing changes sometimes there is no change required to the parts list, but I would still rev the both.  It depends on what you require and if everyone understands the rules.

I suggest going back over threads in this forum, I've seen some fairly good discussions on this topic.

Regards,
-Mike

RE: Bill of materials pt # verses Assembly drawing pt #

Per ASME Y14.35, para 7.1.1(b) - "Revision letters are assigned in an independant sequence against each different type of associated document."

To revise a drawing when a simple change was made to the PL is unnecessary work.  To revise a PL when a simple change is made to the drawing is the same.  The $$ will quickly add up if you make it a rule to keep the revision levels the same (the time required to write the change order, to make the change, to check the change, to release the change).  Change orders can be quite an expense, and I wouldn't want to increase the cost when it is not needed.

RE: Bill of materials pt # verses Assembly drawing pt #

(OP)
Thanks for all your inputs.  The only "grey" areas with my companies part numbering system is this shared part number between assembly BOM and assembly drawing.  As Ewh stated, adding a "PL" to the BOM part # will hopefully straighten things out.

RE: Bill of materials pt # verses Assembly drawing pt #

amckenna,

I see now that I didn't answer the question you were asking.  If you are interested in more information on this subject I suggest the following book..

"Engineering Documentation Control Handbook, Configuration Management in Industry."  Frank B. Watts
This is a good book with both practical information and the theories or reasons backing up his recommendations.  It covers part numbering, revision control, and configuration management.

-Mike

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close