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"Class A quality" surface

Valued Contributor
Valued Contributor
Some NX features claim to create "Class A quality" surface. In the official documentation very little information can be found on "Class A quality" surface. Some information from other software documentation can be found on web.
 
Q1: What does it mean exactly (not roughly "better quality") when a feature claims to create "Class A quality" surface"?
 
Q2: Where can I find more information on "Class A quality" surface, especially guidelines for constructing it with common NX features?
 
Thanks!
6 REPLIES

Re: "Class A quality" surface

Phenom
Phenom

Ciao @surfactant,

in some threads as

 

https://community.plm.automation.siemens.com/t5/NX-Design-Forum/conic-vs-spline/m-p/455282#M19004

https://community.plm.automation.siemens.com/t5/NX-Design-Forum/resources-on-aesthetic-design-cases/...

@StevenVickersgave you some very effective and good tips.

 

When I did my first works of this kind, the best definition of class A surfaces was given to me by a customer: it must be 'bella' (beautiful in english Smiley Happy). 

More than a mathematical definition a class A surface is defined whit what you must NOT to do, never use three sides surface, for example.

Some customers require specifications such as never using Blend command for radii higher than 5 mm, an so on.

I design small parts, I don't work in the automotive industries, I try to work on the details. Below only the red one is a blend.

 

blend.png

 

Re: "Class A quality" surface

Valued Contributor
Valued Contributor

Hi @Cesare Thanks for the very helpful guidance!

Re: "Class A quality" surface

Siemens Phenom Siemens Phenom
Siemens Phenom

Class A, as Cesare states, are surfaces that look good.

Mathematically it is generally seen as a collection of surfaces were the reflection lines are clean, usually this means curvature continuous (G2) or higher continuity (G3) between surfaces and no odd indentations/bulges. But it is more an aesthetic evaluation.

Main commands to get to know are the surface analysis ones such as reflection lines and highlight lines.

 

Steve V

Re: "Class A quality" surface

Valued Contributor
Valued Contributor

Hi @StevenVickers Thanks for the reply!

Re: "Class A quality" surface

Siemens Legend Siemens Legend
Siemens Legend
Another, maybe fading feature is that designer of those surfaces must be able to prove that the surfaces are as good as intended, before going into production. When you are cutting a tool, and find that there are bumps or other defects...
The traditional way of proving this is to look at the pole structure of the surfaces. A skilled surfacer can then decide .
The logical foundation for this is that the surfaces must be as clean and simple as possible, a surface of 20x20 patches is very difficult/ impossible to prove the quality using this method, compared to a single patch surface.
surfaces with high numbers of patches should probably never be considered class A, because NX had to create all these patches to fit the tolerances, which in turn probably means that the curves either are bad , or the shape too complex.
in this, there might be bumps which are difficult to spot before production. This shape should have been created in separate surfaces instead of a single.
Someone mentioned "Class A as informed modeling", - Knowing the result that just got created. -How many patches at what degree did i get ? How are the patch seams ?

Regards,
Tomas


Re: "Class A quality" surface

Valued Contributor
Valued Contributor

Hi @1u7obd Thanks for your comments!