What are the major differences between High-End and Mid-Range CAD ? 1

[John2004]

Hi everyone,

I would like to get some feedback on the major differences between the so called high-end CAD / CAE programs like Unigraphics-NX & Catia, and the mid-range programs like Inventor, Solidworks, and Solid Edge.

What I would mainly like to know is, in general, what can the high-end programs do that the mid-range programs cannot?

Also, where does Pro-Engineer fall in these categories, is it considered a high-end program or is it somewhere in-between a mid-range and high-end program ?

I downloaded a brochure on Pro Engineer and it gave an overview of the Foundation, Advanced, and Enterprise versions, (XE and SE), but it did not say how Pro-Engineer Wildfire compares. Is Pro-Engineer Wildfire the best Pro-E version for mechanical design and how does it compare to the other Pro-E versions mentioned above ?

I would appreciate any thoughts or feedback.

Thanks
John

 

[KENAT]

These days there really doesn't seem to be as much difference between the high end & mid range.

Pro E used to be considered toward the high end, and the pricing certainly reflected this, but I'm not sure that's the case any more.

I will say SE (and I believe SW) are a bit more intuitive/easier to pick up than Pro E, at least when I was learning SE & Pro E at the same time almost 10 years ago.

I had colleagues telling me all kinds of things that Pro E was better at than SE being high range but never really witnessed any. There are certainly areas that it's different and that may be more beneficial in some applications but for what we were doing with it they were equally capable for the most part and SE was easier to use to most of us.

KENAT,

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[ewh]

I can't speak for ProE, but NX is very powerful in surface creation and control, as well as it's integration with CAM and CMM. It is a hybrid modeler, so you aren't limited to fully constrained sketches to create your geometry, but can use a mix of parametric and dumb features as required.
SolidWorks is a very good package for the money, but is more limited in surfacing abilities and downstream integration, and model creation is much more structured.
It boils down to "what do you need".

"The ambassador and the general were briefing me on the - the vast majority of Iraqis want to live in a peaceful, free world. And we will find these people and we will bring them to justice." - [small]George Bush, Washington DC, 27 October, 2003[/small]

 

[KENAT]

ewh is right, surfacing is an area that high end packages are often considered better. This is also an area where Pro E perhaps drops behind the other 2 high end CAD you mention, at least from what I know.

However, my current package has a bunch of surfacing capabilities but I've never got round to learning them so don't know how good it really is.

KENAT,

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[John2004]

Thanks for your feedback guys,

My question is mainly from the standpoint of curiosity & general interest rather than need.

I recently began moving from AutoCAD / AutoCAD Mechanical to Inventor Professional. From what I can tell so far, Inventor will do most everything I need. I have not seen any real CAM support in Inventor whereby you can take a 3D solid model and generate most of the required CNC programming from the model. I'm not sure how the high-end and other mid-range programs I mentioned compare in that regard.

Most of the shops I have worked with tell me CNC programming time is significant, especially for more complex models and models with curves. I would have thought the manufacturers of the CNC machines and/or CNC controllers would have put more time into developing software that can provide the CNC code direct from the 3D model. It seems to me integrating the code generation software right into the CNC controller would be the best option.

It would be nice to be able to provide the CNC programming code to the shops along with the 3D models, just to keep costs down. Will we likely ever be able to generate 100 percent of the CNC programming automatically from a 3D solid model ? As I understand it, it is not really possible to do that reliably and consistently at present.

As far as my initial question, I'm hoping someone who has had a fair amount of experience with at least one of the high-end and one of the mid-range programs can give me the basic rundown on what the high-end programs can do that the mid-range programs cannot.

John

 

[ewh]

Automatically, maybe some day. You can do the CAM programming directly on the NX models, and machine from the same model that was detailed on the drawing. Same with CMM. Finally you can rely on only one version of a part to do the downstream operations instead of relying and controlling multiple translations.

"The ambassador and the general were briefing me on the - the vast majority of Iraqis want to live in a peaceful, free world. And we will find these people and we will bring them to justice." - [small]George Bush, Washington DC, 27 October, 2003[/small]

 

[KENAT]

Solid edge has a 'partner' product that does the CMM from the SE model.

One issue to really take advantage of taking the model straight to CAM is to have, and enforce, modelling rules/conventions that support this. For instance do you model features at max, min, nominal or mean tolerance?

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

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[John2004]

I model the part exactly as it is, i.e., whatever dimension or feature is theoretically perfect, is how I model the 3D part. Then on the production 2D drawing, I add dimensions and tolerances to the theoretically perfect part.

Whether the theoretically perfect part would fall in the mean, min, or max of the tolerance would depend on whether I used bilateral or unilateral tolerances, but in any case, I always make the 3D model at it's theoretically perfect dimension, and then tolerance the 2D print as necessary.

If the part or a part feature would work better at it's low or high tolerance, perhaps I would model it accordingly, it all depends on design intent and function. For example, if I have a hole or bearing bore in a part and it's best to have the hole at it's low side of the tolerance, then I will generally model the hole at it's low side of the tolerance. In that case, on the 2D print I would go with a -0.000 / + XXXX tolerance as appropriate.

I generally think more in terms of function and design intent rather than CNC programming. I tend to think that CNC programming should adapt to a theoretically perfect model that is designed with function in mind, rather than adapt an imperfect model to the CNC programming.

Does it make sense from a standpoint of CNC programming to model the 3D solids at the min or max tolerance instead ?

Thanks
John

 

[ajack1]

I would say the three main differences are surfacing, surfacing and surfacing. If you don’t need that then fine.

Also it is possible to machine to models now with very limited manual input provided you have the right CAD/CAM software, but some is still required to get the best and quickest results. It does take time and effort to set up controls and standards and as far as I am aware they will be unique to your company rather than some world wide standard, but when you see the time savings and the amount of errors it eliminates it is well worth while IMO, but once again this depends largely on what you are trying to achieve.

 

[TheTick]

w.r.t. surfacing:
Pro/E lets you play doctor; UG/NX lets you play god.

 

[KENAT]

John, what is theoretically 'perfect' to you may not be to the machinist, that was my point.

I've had people claim that to support importing the model to CMM you should model at mean and others argue you should model at I think it was LMC to allow for tool wear.

You'd need to talk to your machinist (or investigate your CAM software or whatever), work out what's best for them and then implement those rules.

We mostly rely on 2D prints as the master but often send a copy of the model to aid with programming. However, we haev a disclaimer (or are meant to) stating the print is the master and the model for reference only.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

http://eng-tips.com/market.cfm?

 

[looslib]

I think the difference is becoming blurred, but surfacing is a big difference. One other area that was hinted at was the integration between CAD and CAM. High-end systems have integrated CAM while mid-range systems have CAM add-ons.


"Wildfires are dangerous, hard to control, and economically catastrophic."

Ben Loosli

 

[John2004]

I do what you do Kenat, I consider the 2D print as the master but I always send the 3D models along to aid in programming and in visualization, i.e., they can rotate the part around in their own CAD / CAM and see it from any view they want.

I understand the point you are making in that the machinist may want the CAD model to be a certain way for programming.

IMHO, I tend to feel that design intent and function should be the governing factor and it makes sense to create the CAD models and/or virtual assemblies with that in mind. I would rather see CNC programming techniques adapt to a model that is dimensionally perfect from the standpoint of function, rather than create a model that is perfect for CNC programming but not so perfect as far a function (even if it's still within tolerance).

I have heard before that surfacing was the big thing with the high-end programs. Is it mainly a matter of efficiency, (i.e., the high-end programs are just quicker at surfacing) or can you model things with the high-end programs that simply cannot be modeled with the mid-range programs ?

Thanks
John

 

[KENAT]

John, that's where the conflict of getting the most out of the model from a manufacturing point of view V capturing design intent/based on function comes in.

It's a carry on from the arguement of should your drawing dimension scheme be based on function or to ease manufacture.

I like you lean toward design intent & Function and believe from a drawing point of view that's what the standards say, or in some cases maybe only imply (at least US ones). However, when direct cost is more of a concern than Quality, the argument might be made for making it suit manufacturing.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

http://eng-tips.com/market.cfm?

 

[mcgyvr]

Inventor also has partner companies that support direct importing of the 3d model into the cam package. Mastercam as well as many of the other more popular cam packages support direct importing of just about every cad package format now.

I use inventor all the time and while I do very little surfacing there is almost nothing that can't be accomplished with Inventor. I always send a 2d print and a step file to our vendors, they import the step file to program the fabricators and use the prints for any details/specs that cannot be defined in the 3d model.