CAD Softwares that We Love (or Hate)
- mingyichen95
- Dec 22, 2023
- 11 min read
Thankfully I never had to do drawings by hand. Although I think that might have been useful because it probably forces one to be careful. Today engineers like myself use what is called Computer-Aided Design (CAD) software to do all of our design work. This encompasses more than creating 2D drawings like those done by hand in the old days, but also, in a large part, 3D modeling and analyses. People often use the term Computer-Aided Engineering (CAE) to denote purely the analysis portion, usually involving some form of finite element analysis. Thus, the term CAD, usually would refer to only the design portion, answering the question "will these parts fit together and have the right tolerances" rather than "will these parts endure a random vibration environment”. But then again, many CAD packages also have CAE software integrated into them. So it's not really that separate. There are many flavors of CAD software on the market today, however, in my opinion, no single software can claim to be the best at everything. To the same logic, no software that hasn't gone out of the market can be said to be atrocious at everything. Each company tends to stick with one CAD package for various reasons including costs, important legacy design files that have already been natively created in a particular software, learning curve for a different CAD package, established business relations, as well as technical capabilities of a CAD package. With all that said, allow me to share with you my opinion on some of these.
It is common practice to design the 3D model first and then make 2D drawings from it.
First up, Solidworks by Dassault Systèmes. I'm not sure if it is the most popular 3D Parametric CAD software, but it is certainly popular, I will give it that. It is often the entry point to the world of CAD. And yes, it was also my first CAD software and I did great things with it. Solidworks is quite prevalent in education environments because of the ease of obtaining an education license for it for free, and usually it comes with all the features of the commercial versions, except all the CAD files created would have watermark entities indicating that the file cannot be used for commercial purposes. My first Solidworks project was in FIRST Robotics, and it was quite intuitive to pick up in a few days. Due to its popularity and large user base, copious tips and tricks can be found online in the form of Youtube videos and forums, with FIRST Robotics already comprising a portion of that user base. The next few times I used Solidworks involve my undergrad senior design project, and my first engineering job. One can also show one's expertise by taking certification tests offered by Dassault. And yes, Solidworks skills are great to have on a resume.
The Intuitive Interface of Solidworks
But does Solidworks work technically? Yes actually, not without some downsides as well. It performs well as a parametric 2D and 3D design software (modeling that usually has a time-ordered feature tree with features having parameters like length, width, and height that can be updated and changed at a later time after feature creation).
Solidworks Pros:
Easy to pick up
Buttons and menus are easy to find
Powerful for solid modeling
Imports and exports files of other formats well
Has good suite of rendering support
Easy to get education license for students
Good community support and information
A lot of handy modules and features that decreases amount of work like sheet metal, weldment, copy with mates, or simply just ctrl-c to copy parts, and ctrl-v to paste.
E-drawings viewer software allows a person who doesn't have solidworks installed to view in 3D a solidworks 3D design, hide parts, and measure dimensions. This is particularly useful for design sharing or to save money on another seat of Solidworks.
PDM (Product Data Management) software amenable to be set up with a small server computer and not much training.
Simulation tool is easier to set up and run.
Solidworks Cons:
Not very good with surface modeling
Stability issues are more frequent compared to NX and CREO in my experience
PDM software suite not as polished as Teamcenter or Windchill
Large assemblies can become broken with more ease than NX or CREO, i.e. parts with unsolvable mates will shift and float elsewhere instead of staying where they are.
An older version will not open files saved in a newer version, thus organizations are sometimes reluctant to updated to newest version and users also have to install multiple Solidworks versions when working with teams that may be on another version.
Simulation suite not as powerful as ANSYS or NX Nastran.
Second up: CREO Parametric made by PTC (Parametric Technology Corporation), formerly known as Pro/Engineer and Wildfire. CREO was the next piece of CAD software that I used professionally. It was relatively easy to transfer what I knew from Solidworks and apply it to designing in CREO. However there were also CREO idiosyncrasies that presented challenges. In the community, CREO and NX and CATIA are somehow viewed as more mature and advanced than the likes of Autodesk Inventor or Solidworks. It certainly has to do with the costs as well as capabilities. Inventor and Solidworks are by no means not capable, but aerospace giants and other big companies tend to, one, be able to afford CREO, NX, and CATIA, and two, need some of the more comprehensive capabilities of CREO, NX, or CATIA. In my limited experience, Solidworks and Inventor are great for design, and it was only in a really big organization that CREO, NX, and CATIA shine because better PDM (Product Data Management) systems are more robust and mature with these when huge teams need to access the same design files and when diverse groups of people need the CAD/CAE software package to excel at abilities like thermal analysis of PCB boards and also be good at surface modeling. Usage by big companies does not necessarily mean that CREO, NX, or CATIA are superior to Inventor and Solidworks. It comes down to the specific engineering needs and wants. In fact, Solidworks and Inventor are more intuitive to use.
CREO Subjectively has a more vibrant color pallet.
CREO Pros:
Relatively easy to pick up.
Windchill PDM software integration is by far the best I have used.
3 types of FEA analysis options available, two Ansys based and one PTC based gives flexibility to chose one that fits one's needs, CREO Simulate live takes advantage of a CUDA enabled graphics card for acceleration (graphics card acceleration is night and day compared to CPU 1 minute vs 20 minutes).
Sketch relations are intuitive to apply.
2D detail and sections views are highly customizable even though drawing the splines can be a bit weird at first; z-clipping is useful.
Software stability: it will slow down and it will take a while to recover from time to time but it almost never crashed outright.
Support through PTC is good if it's paid for by one's company, but on public forums there is less information than Solidworks or NX.
Student version is available.
Very good parts finder in assembly mode, comes in handy when trying to count screws, will highlight said part in green and show location in the assembly.
CREO Cons:
Centering constraint not available in assembly, need to use two center planes as workaround.
Creating patterns and groups has a learning curve. Solidworks handles this better.
Previews on operations not as good as on Solidworks.
The green star indicating which part is activated is not as clear to a new user as having parts boldened or change color in the design tree.
Not very intuitive wire routing tools.
Stacked bubble callouts in 2D mode and brackets require custom templates.
No copy with mates/constraints function.
In summary very powerful tool that can be made to do anything, but many features are not as intuitive or easy to implement.
For some reason, or for good reasons, my next job used NX by Siemens, previously known as Unigraphics. So yeah, every company or even separate divisions and/or programs use different CAD software packages. Does this create chaos when programs and divisions have to work together? Yep, it does. Could it have been avoided? Probably. Was it avoided? Nope. Is there a workaround? Yes, not perfect. Sometimes CAD software can take really good generic universal files in formats like Step and Parasolid and re-establish a feature tree. This is not perfect, and a lot of times, the Step file cannot be translated. This results a sort of dumb solid. Think of Step and Parasolid files as finished dishes. Sometimes a dish can have its original ingredients and the cooking methods inferred, and sometimes it is a solid piece of cake. Another cook can modify this cake by cutting it, but can never take out the sugar in it if it was too sweet. So yeah I ran into this problem when coincidentally working with NX. Old files were in Solidworks. I exported step files from solidworks and had NX read the Step files. Unfortunately, the NX files are now dumb solids, which were still modifiable to some extent by NX. However, I lost the feature tree. 2D drawings became even more challenging as there is currently not much one can do to do 2D drawing translations from one CAD package to another. In this case, even if it were minor changes, to go from Solidworks to NX, I had to re-create 2D drawing files. So yes, once you pick one CAD software package, it is very difficult to switch to another if you also had to modify an old design in the old CAD package to make a new design in the new CAD package.
NX (Unigraphics) Usually have menus with options to give the user precise control.
NX Pros:
Robust support base both paid and on free forums and youtube.
It is powerful and comprehensive, if there's a feature not available you can usually contact your Siemens rep to consider adding it.
Stability and Speed: I have had one crash so far. I would rate it about the same as CREO, with way less hang times (near crashes).
Selection filter is done very well and allows you to pick exactly what you intend to.
Also a con, but also a pro: Many knobs and options to turn and set to do exactly what you want to do. If Solidworks was Mac OS X, NX is windows, and CREO is somewhere in-between. Although it can also work out of the box, if you want it to do specific things, you have to go and set it. It won't read your mind. This is also good power to the real power users.
Assemblies keep parts in place and rarely break if there are unsolvable mates like Solidworks. Of course, this is user error tolerance.
NX Nastran and Simcenter have capabilities beyond ANSYS and Solidworks Simulation, even CREO's simulation tools aren't as capable in niche applications like PCB thermal analysis where the PCBExchange tool in NX can extract detailed copper traces and component reference designators from board design files. In many other simulation tools, one would have to manually create the board model layer by layer and manually. For structural analysis NX also has very configurable nodal and beam elements whereas in ANSYS it's not as straightforward.
NX Cons:
Hidden buttons and functions, often default options are not what the user would want either. Too many knobs to turn for some new users. Again also a pro for the power users who knows what they are doing.
Learning curve is higher than CREO or Solidworks.
Reference sets and assembly load options unintentionally suppress components.
Every new update of NX defaults to a new Sketcher for creating sketches in modeling that is not dimensions and sketch relations based, but tries to infer what the user is trying to sketch. This has broken some of my designs before.
Teamcenter PDM software is not as well-implemented as PTC Windchill that is used with CREO, there is no distinct folder structure and it is hard to search for parts without the exact part number. For example, I was able to find the drawings to a famous contraption that is in space right now with just its name in PTC Windchill.
NX Simcenter and NX Nastran is more difficult to learn than ANSYS or CREO Simulate because there are many hidden knobs and menus that give one powerful options, at the cost of being easy to work with.
Drawing files and 3D part files and assembly files are all .prt files, it might become confusing to new users to have to switch from modeling application to the drafting application on the same .prt to edit each portion of the .prt.
File import and export from different formats are not as straightforward as Solidworks, either there are too many menu options or a certain format like .DXF become imported as vector geometry and become invisible in model because it was not added to the correct reference set.
Many of you might be wondering why I haven't talked about AutoCAD. I get it, CAD is in its name and it is one of the oldest CAD softwares around or maybe Autodesk did do some great marketing. But it really isn't a main staple for a mechanical engineer. At most of my jobs I have came across the need to work with .DXFs. For some reason the industry still likes this format for a lot of things like natively inputting into middleware that drives laser cutters and water jets. Electrical engineers also love .DXFs for doing schematics. This format is what AutoCAD by Autodesk is famous for. AutoCAD .DXF files are great for storing and transferring 2D vector graphics. In my opinion though, many software 2D sketchers like those in Solidworks and NX aren't lacking in capabilities compared to AutoCAD. AutoCAD by comparison is not a parametric CAD tool and it is not too good with 3D. It is thus unfair to compare it with other CAD software we have discussed thus far. The workflow in AutoCAD revolve around drawing lines and curves and inputting their specifications as you draw them. However, unlike parametric sketches, we cannot dimension them later and have them obey certain relations to one another like perpendicularity and coincidence. What AutoCAD is good at is its simple interface and powerful command line that allows users to copy, paste, trim, extend, and move 2D graphics very easily. However, it is rarely used for mechanical drawings because mechanical parts usually need good 3D modeling support. For schematics with 2D lines, AutoCAD is still really good. The learning curve is low also. Yes, you can also do that in Solidworks but it is not as fast as typing in the AutoCAD command line that is always on "LINE", draw a line, and then "TR" to trim what that line you just drew intersected with. And then also put the trimmed geometry on another layer with a click of a drop down.
And I will also comment on some CAD softwares that I have used, but do not feel I have enough experience with to make a full opinion on.
Inventor by Autodesk is a direct competitor to Solidworks. I have used it in my undergrad years because, it worked really well for generating .DXF files from 3D models that can be then fed into a laser cutter. What a surprise that the same company that makes AutoCAD makes it easy for Inventor to work with AutoCAD .DXFs. The reverse is also true: one can easily import .DXFs. For the handful of times I used inventor, it was pretty good for solid modeling. It was even easier to obtain than Solidworks in that you can just go straight to the Autodesk website to download the student version without having to request a license. The feeling I got was that the philosophy was to make everything as easy as possible to do, sometimes at the expense of not having the knobs to turn for fine tuning things as in NX.
CATIA V5 by Dassault Systèmes is another powerful CAD software that has been in use in the aerospace industry since before I was born. In the week that I played with it, I didn't like it and the learning curve I felt at the time was very high compared to any other software on this list. I did find enough support online to guide me to create a simple assembly, but the interface felt like it was from the 90s. The rotation and pan and zoom was very unintuitive. This opinion may have been too harsh on it. From what I have heard and seen, CATIA is great at surface modeling and powerful for working with very large assemblies like jumbo planes, and people do eventually learn to use it well. From what I've heard, CATIA has as many knobs and features as NX if not more. Big aerospace companies sometimes use CATIA for the absolutely big products and then another CAD software for many other products, but having to CAD systems can introduce challenges when the two systems need to talk to each other.
There you have it, most of my honest opinions on CAD softwares. I hope that was informative and I hope I didn't make all these CAD companies cry. I mean come on, there was one instance where the official company website workaround to a missing feature on one such CAD package was an admittance to said feature missing and I didn't call you out.
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