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

Form, Fit, or Function

Form, Fit, or Function

Form, Fit, or Function

Hello to all,
This is my first post here! I wanted to start off by thanking the community for this chance to discuss a few topics that has come up a few times already.

So I have been designing for 17 years now in the fields of Mechanical machine parts and assemblies, MEP, and Architecture disciplines. Just recently the company which I have been with of going on 5 yrs, has been looking at setting up standards for ECO process and revising drawings. We had a large debate on when to revise or create a new P/N for changing parts. I have always worked off the three "F"'s. To my surprise, ANSI does not follow that. My question is "how was I misled this whole time or did the standard change when ASME and ANSI combined?

All of my experience says to revise a drawing if there is a change to the Form, Fit, or Function of a given part. ANSI states if a part is not backward compatible then is gets a new part number not a new revision.

What are the thoughts of this community?

Nathan Gardner
Mechanical Designer / CAD Admin
Wood Carver - Cheese Maker - Goat Farmer

RE: Form, Fit, or Function

If a part is not backwards compatible, then it is considered a new part and should get a new part number. You are correct too, if FFF changes it should always be revised. The caveat is that some FFF changes should require a new part number as well. I also think it matters if you are building one-off products or not. Example: a safety bar that is 32" long, and it is rev'd to 32.5" long. Customer order new bar and complains it doesn't fit. That change should have triggered a new part number.

"Art without engineering is dreaming; Engineering without art is calculating."

Have you read FAQ731-376: Eng-Tips.com Forum Policies: Eng-Tips.com Forum Policies to make the best use of these Forums?

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


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