Computer Aided Design tools have been around for many decades and all are likely to be able to do most, if not all of what you need from it, so how do you choose which is the best one to buy if you are just starting out, or if you are thinking of changing?
There will also be some questions you will need to ask before you hone down on your choice of CAD. Some typical questions will be:
Which CAD supplier has the best future planning?
Do you want the CAD to be installed and run on your computer or in the cloud?
How should it be licenced?
Locked to a user/computer
Cloud managed
Any user on a network
How can you pay for the licence?
Subscription (only access while paying an on-going fee)
Perpetual (yours to run as long as computer lasts)
Let’s be honest, most of us prefer the first CAD system we learnt first, either what we were taught at school or University, or on our first job, but does this mean that it is the best or most efficient solution?
The first point I will make, is that the strength of any design comes from the designer, not the tool, so good and bad designs are created using all CAD tools. What you are really looking for in a CAD tool is the one that is going to give you the most flexibility, the best ease of use, the best stability and has the best vision for the future. You also need to make sure that you choose one that will stay with you as your needs grow. The need for re-training and migrating all of your legacy data are often given as excuses for not changing your CAD tool, but are these valid?
Yes, re-training will take a little time, but you are only likely to be slower for a small period of time and if you choose a more efficient and flexible CAD tool, then you will re-coup that short learning curve and reap the rewards of getting more work done and more quickly in no time!
Legacy data is a more complex issue and is the reason why users are less keen to change. CAD tools have two tiers, the kernel and the interface by which the geometry is created. The underlying layer is the kernel, which you can think of as the geometry engine. The program feeds the kernel instructions, and the kernel produces geometry. There are many geometry kernels in existence, but only a handful are in broad commercial use. The big players are Solid Edge, NX (Siemens), Solidworks and OnShape, who all use the Parasolid kernel (owned by Siemens), CATIA and 3DEXPERIENCE (Dassault Systèmes) with the CGM kernel, Inventor and Fusion 360 (Autodesk) using Shape Manager, with Creo (PTC) using their own Granite kernel. Dassault Systèmes also owns the ACIS kernel, which Autodesk used as the basis for their ShapeManager kernel.
The other part of the CAD file is proprietary and defines how the geometry is built. You can think of this as the intelligence in the CAD file and it is not shared and is not transmitted in a data translation.
There is no common language between programs to share this kind of information—even between programs that use the same kernel. Programs cannot, by default, use each other’s proprietary formats and most importantly, cannot share the parametric details of the feature tree. The most you can share is the stripped-down data from the geometry kernel.
This is the basic conflict engineers must resolve when attempting to use CAD data created in different tools. The tools are not meant to talk to one another, and you can only get them to share the geometry, not the intelligence that went into creating the geometry. Therefore, you need a tool that is going to handle converted/imported geometry so that you don’t have to re-build designs from scratch.
Furthermore, you also need to look at how collaboration will work. Migration tools are all well and good when you wish to move your own data to a new system, but what happens when you outsource parts of your own design to specialised contractors who may be using a different CAD system? Therefore, the CAD system you choose should be one that enables you to easily encompass their designs without having to convert their CAD data into your own systems’ proprietary format, because when updates are done, there is no easy way to update and replace the new design.
One other thing to consider is where will our investment takes us as the company grows? You may only need CAD to start out with, but if you need to get CAM, electrical, plant design, PDM, etc, are there ways of expanding your tools with the same supplier and do they have a plan for the future?
Personally, and I am obviously biased, I can’t see a better solution that what Siemens are offering, so let’s look at some of the reasoning behind this statement.
Future-proofing
Both of the CAD tools from Siemens, Solid Edge and NX, are built on the same kernel, so the basic concepts, tools and workflow are similar, even more so with the latest release of Solid Edge. Furthermore, as Siemens own Parasolid and the geometry solver (DCubed), they are in total control of all development. There is a tight integration between both, enabling files from one to be inserted into the assembly of the other. Like most companies in the industry, Siemens have been known to buy out other software to extend into areas that they have not yet got a full solution. The strength of how Siemens do this is that they then integrate it into the ecosystem of their product offerings and ensure that there is proper collaboration to ensure that efficiency is paramount.
Now compare this to the other main players in the market. Dassault own Solidworks, which is built on a kernel owned by a competitor, so they have developed 3DExperience, which is built on their own kernel, CGM, to replace it. Dassault seem to have been pushing for users to switch from Solidworks to 3DExperience for several years (as they have renamed their annual conference Solidworks World with 3DExperience World), but the traditional Solidworks users don’t seem to be buying it. The main reasons for this may be due to the fact that 3DExperience is subscription only, while many of their users prefer the maintenance (perpetual) model? Autodesk have a habit of releasing many products (either developed in-house or purchased), but often don’t integrate their offerings. What is the integration between Inventor, Fusion 360 and even AutoCAD? They also have a history of dropping products too, so is there a market for both Inventor and Fusion?
Part of the future-proofing involves the product offerings that are surrounding the mechanical CAD tools, so when your needs grow, you know that there are good integrated tools that allow you to branch into differing disciplines, such as electrical, FEA, CAM or data management.
As shown by this graphic, Solid Edge (and even more so with NX), has many tools that are fully integrated to help get designs done faster, including bi-directional updates between applications. Solid Edge has built-in FEA tools and also strong links with Femap for higher end analysis. The CAM tools also have a tight integration, whereby the tools are separate (as CAD and CAM users are usually different people), but there is a direct link from the CAM to the CAD model, ensuring that updates to the models can flow directly into the CAM without having to rebuild the tooling operations. As you grow, data management will become a higher priority to ensure that designs are managed properly. Solid Edge has some basic built in data management tools to handle the early phases and Teamcenter is there as your needs grow, offering a PDM that not only works with NX and Solid Edge, but most other CAD formats and is also embedded into Microsoft application so storing data from there is an easy click away.
Solidworks has a good suite of tools available, but on further investigation, there may be some concerns. Solidworks CAM seems to be a solution that is tied to a partner (HCL Technologies) rather than being owned by Dassault. SolidWorks PDM is their 3rd time attempt at PDM, with little or no upgrade path from their earlier attempts. SolidWorks PDM manages files not containers, thus references need to be created manually which is a time consuming and error-prone process. With the drive to push users into 3DExperience, there will also be a push to move users over to Enovia, which appears to be a start-over affair. Many of the new tools seem to be added to 3DExperience, so beware if you are not keen on the subscription model.
Autodesk have a good range of complimentary products, although their CAM offering is embedded into the CAD, which ties up a CAD seat when CAM is being used. Autodesk Vault is their PDM option, but is not as fully featured as Teamcenter, which has integration for a lot more products and more advanced tools for managing the lifecycle of products. Electronics with Inventor seems to be weak, while fusion has ECAD functionality, and is again built into the CAD, whereas in most cases the electrical and mechanical engineers would be working collaboratively, but separately.
PTC is a high end system, similar to NX from Siemens, and so has a good array of add-on products, but is considered much harder to learn and use, compared to the mainstream CAD tools, such as Solid Edge and Solidworks.
Migration
You need to make sure that if you are switching from one CAD tool to another that there are adequate tools to help with a full migration. The migration tools should be able to read in 2D and 3D geometry and also transfer the links between parts, assemblies AND drawings. As stated earlier, even if you can migrate your old data to your new CAD tool, you will still need to be able to edit the designs and so you will need to make sure that the new software has a good means of making edits above the simplistic move and delete faces options.
Solid Edge provides bulk migration tools for parts, assemblies and drawings from popular CAD systems (such as Solidworks, Creo and Inventor), reading in 2D and 3D geometry, which also transfer the links between parts, assemblies and drawings.
Solid Edge comes with a range of tools to facilitate a smooth migration. Designers and engineers can directly open models, drawings and other deliverables created in other CAD formats using native Solid Edge. This allows designers to avoid data translation by using neutral formats. As a result, they no longer have to spend hours painstakingly fixing broken geometries, resulting in massive time savings. In addition to opening individual files, these capabilities provide an accelerated and more straightforward path to transitioning to Solid Edge, enabling designers to make a strong business case to switch to Solid Edge from most CAD applications in the market.
Like most other CAD tools, Solid Edge cannot bring in the feature tree, but due to the direct edit (synchronous technology) tools available, edits can be made with a lot more efficiently and capably that just moving faces.
Solidworks seems to assume that migration isn’t too important and offers very limited tools for bringing in legacy data. The options include leaving the geometry as is and just placing in an assembly if needed for reference, using feature recognition, which is fine on simple parts, but not so easy on complex parts and also very time consuming. The last option is to use direct edit (or move face), which is very limited if trying to make detailed changes. There is no mention of linking drawings to models, so that would require more re-work if you can manage to make changes.
Inventor appears to have the same set of tools to solidworks in terms of dealing with imported files – reference model (have the file as an un-editable reference in an assembly) or convert model, which creates no features and can only be edited by adding new features (Cuts/protrusions) or moving faces. There does not appear to be any way of converting and linking 2D data. Fusion 360 is no different.
Creo has a number of tools for editing imported models, similar to synchronous technology in Solid Edge and NX, although tools such as the design intent (which allows you to turn off or on the geometry recognition) and selection manager (which allows you to recognise series of face as features, etc) seems to be lacking. There also seems to be a lack of migration tools that will keep assemblies and drafts linked to the model.
Deployment
An important decision for your CAD choice is what is your preferred deployment model. This chart shows clearly whether your chosen CAD tool will be run and stored in the cloud or on your own desktop.
| | On-Premise | Cloud |
Siemens | NX | X | |
| Solid Edge | X | |
Dassault | CATIA | X | |
| 3DExperience | | X |
| Solidworks | X | |
Autodesk | Inventor | X | |
| Fusion 360 | | X |
PTC | Creo | X | X |
| OnShape | | X |
Modelling
There are two styles of modelling cultures, one is parametric modelling (developed by PTC with Pro/E) to manage designs feature by feature, where you can roll back a design to that feature, edit it and the whole design will then rebuild back to the end. The other is direct edit, where features are created in a similar way, but once the feature is created, intelligence is lost and it reverts back to basic geometry that is edited by pushing, pulling and rotating. Synchronous technology from NX and Solid Edge extended direct edit tools to make it parametric and controllable through automatic geometric constraint recognition, geometric
constraints and controlling dimensions. It does not stop there either, as you can combine both styles of modelling in the same file ensuring that you have the best of both worlds. This graphic shows where the strengths and weaknesses of both exist and how Synchronous Technology takes the best of both worlds. Most other CAD products claim to possess direct edit tools, but are still another feature in the feature tree.
This table shows what style each of the main CAD tools use.
| | Feature | Direct Edit |
Siemens | NX | X | X |
| Solid Edge | X | X |
Dassault | Catia | X | |
| 3DExperience | X | |
| Solidworks | X | |
Autodesk | Inventor | X | |
| Fusion 360 | X | |
PTC | Creo | X | X |
| OnShape | X | |
Licencing
This is another area that has polarised many uses and there are two areas that it covers – how you purchase and how the licences are allocated.
A few years back, Autodesk took the step to make all new licences subscription, ie paid annually, so when you stop paying your subscription/rental, you lose access to the software, and this is now a very common practice in the IT industry. The older style is perpetual, whereby you pay for the software and then pay an annual maintenance that entitles you to support and upgrades, but when you stop paying the annual maintenance, you can continue to use the software at the last available version.
The licence allocation is achieved by issuing the licence in one of three ways. With a floating licence, the licences are purchased (at a slightly higher cost) and are served out from a server such that users can check out licences until all have been allocated. With this method, the software can be installed on any computer in the network and provided the licence is free, then the user can open the software. Node locked licences, often called named user, are locked to an individual user or computer. The cloud licence is one that works like the floating licence, but instead of allocating the licence from the server, the user logs in over the cloud to obtain the licence, but the software is still installed locally.
| | Perpetual | Subscription | Floating | Node Locked | Cloud |
Siemens | NX | X | X | X | X | X |
| Solid Edge | X | X | X | X | X |
Dassault | CATIA | X | X | X | X | |
| 3DExperience | | X | | X | |
| Solidworks | X | X | X | X | |
Autodesk | Inventor | | X | | X | |
| Fusion 360 | | X | | X | |
PTC | Creo | | X | X | X | |
| OnShape | | X | | X | |
Training
This is becoming less of an issue these days as there are so many tutorials on youtube that can help you get started. Most programs will have an in-built tutorials and resellers will have their own courses which they can offer. A good reseller will be able to customise a course specifically for your company too. As explained above, once you have an understanding of how to build models in CAD, then skills should be quick to transition to a new CAD program, remembering that the real skill is in the designer.
In Summary, I believe that Siemens, who are synonymous with engineering across the board, offer the best choices. Solid Edge and NX have two modes of working with feature based and direct edit, meaning that you can choose what works best for you for each design. The tools that they offer are intuitive and easy to use, which includes a tool to help you find the commands you are used to from other applications. The suite of complimentary tools available cover most areas of the engineering industry and are also well integrated to ensure that you are working in the most efficient manner possible. The licencing options on offer provide a great choice (which includes free licences for students, schools and hobbyists and a minimal cost to tertiary). With products that are established in the market, such as Teamcenter, Femap and NX/SE CAM, to name a few, there is always a way to have your software options expand if and when you do. If you need to switch from a different CAD program, then Solid Edge and NX give you so much more in terms of migration by offering not only translation from the old system, but a set of linked files, from parts that can be easily modified using synchronous technology, to assemblies that have relationship converted rather than grounded parts and the additional advantage, that seems lacking in most others, a linked 2D drawing.
Disclaimer – while I have done my best to research competitive products, there is a chance that I have missed details. For full details on competitive products, please consult a reseller.
If you want to learn more, then contact me on alan@cadcentral.co.nz