×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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!
  • Students Click Here

*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

Best Practices to prepare CAD model for CAM
3

Best Practices to prepare CAD model for CAM

Best Practices to prepare CAD model for CAM

(OP)
Are there any best practices to follow regarding CAD model preparation for CAM?

Nowadays, most of the CAM are feature based CAM, which is going to use the CAD model for tool path generation. Hence, the accuracy of CAD model affects output of CAM.

So regarding this, I have the following questions:
1. What are all the best practices?
2. Suppose if my part tolerance as per engineering drawing is 50 microns, what should be my model tolerances?
3. Should I increase the no. of poles / control points using the X-form or I-form to increase the accuracy of surfaces? (Note: Assume the model we get is in unparametric form)
4. If we use different CAM package (other than NX CAM), then what is the best neutral data format(IGES or STEP or parasolid) to have minimum data loss? Is there any setting which we should take care while exporting the model?

Any ideas are much appreciated. Thanks.

RE: Best Practices to prepare CAD model for CAM

2
I always check the solid model for errors before passing it on for CAM.

MENU -> ANALYSIS -> EXAMINE GEOMETRY

If any of the seven Checks within the red rectangle give a negative result they need to be fixed.
The other four Checks depend on the application.

Jerry J.
UGV5-NX11

RE: Best Practices to prepare CAD model for CAM

Perhaps drop the default OOTB modeling tolerances a little. I had a manufacturing tolerance issue a while back and GTAC determined the modeling tolerances were at fault. I seem to recall the variance was in the .0002"-.0004" range. On the large end that is approximately 25% of your 50 micron tolerance so perhaps using slightly smaller modeling tolerances could help.

I second Jerry's recommendation for Examine Geometry which will give you a good idea as to model quality although you could go directly to using Optimize Face in Synchronous Modeling to clean things up. File-Export-HealGeometry can fix a lot of anomalies too. Not sure about other cam software but NX seems to be very forgiving with dirty models with only very rare problems rising from anomalies. If your models are complicated then I recommend cleaning them up as part of your prep workflow.

I haven't heard that increasing surface poles/control points accuracy impacting cam. It really comes down to what you require for model accuracy; not so much for machining; it will give you what the model is.

As for data format obviously native is best; feel free to delete model parameters for IP considerations. Parasolid is a very commonly used format and STEP behind that and lastly IGES, IMO. Some software have issues with IGES. If you don't mind creating multiple files I would make a Parasolid file and a STEP file. Another consideration is the Parasolid version. You could run into a rare version issue if someone is using an older cam software. I wouldn't worry too much about it; most companies keep their software up to date but if you want you can easily output Parasolids a couple versions old.






NX 12.0.2
Testing series 1872
EVP's

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


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