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For Downloadable CAD Models, Do CAD File Formats Matter

We’ve been asked this question many times and it has aroused some controversy so here’s our detailed answer.

Firstly – what are CAD model downloads and why are they important? Many industrial websites (manufacturers and distributors) now offer online CAD models of their components (such as gears, bearings, etc.) and engineered products (such as motors, gearboxes, etc.) for designers to download and include within their new CAD designs. This serves both parties well, designers save time by not drawing from scratch and suppliers’ get their parts incorporated in new CAD designs for later purchase.

Now to answer the ‘do file formats matter’ question: for CAD models there are two sides to this question, firstly the CAD format in which an industrial supplier’s master models are built and maintained and secondly the CAD format or formats in which derivative models are made available to CAD users for download.

1. CAD Format for Building and Maintaining Your Models

Your master CAD models should be built in a format that leaves you free to use them in any CAD system or any CAD Download system in case you need to change vendors in the future. You don’t want to be constrained or locked into any one vendor’s CAD system (including the CAD systems of any CAD Download Solution vendor).

Therefore you should always choose that your CAD models be built in a top commercially available CAD system – we recommend PTC’s Creo(R), Dassault Systemes’s SolidWorks(R) or Autodesk’s Inventor(R). That ensures portability but also be sure to retain full ownership of your CAD models into the future, whoever might build them for you.

Beware of any CAD download vendors who attempt to lock you into their proprietary CAD formats built using a non-commercially available CAD System and thereby restrict your ability to change vendors in the future.

2. CAD Format for Downloads of Your Models

The CAD format of models that your customers’ download is a more complicated question and there is much misinformation on this topic especially by some other digital part catalog and CAD download solution vendors. For example some CAD download solution vendors even contrive ‘survey questions’ to try to ‘prove’ that native formats are preferred. Similarly survey questions can ‘prove’ the opposite – in our March 2014 survey we asked:

When you download a supplier’s CAD model, do the interchange formats such as IGES, STEP, Parasolids, SAT meet your needs? 90% of those answering said YES (ref: CDS Survey March 2014)

The reality is that CAD formats really don’t matter any more with respect to importing them into a new CAD design because all the major CAD systems import a wide variety of formats including their own proprietary (also called ‘native’) formats, other CAD vendors proprietary formats (for example see Chad Jackson’s Creo-to-Open-Native-CAD-Files or PTC’s What’s New in CREO 3 presentation) and industry standard exchange formats (such as STEP or IGES).

Why? Because these CAD systems have to meet stringent standards of compliance to industry standards in order to be purchased by governments or major corporations. Those organizations frequently use multiple CAD systems internally and/or in their supply chains. Therefore your downloadable CAD models can be supplied in either proprietary or standard formats but there are two good reasons to prefer standard exchange formats.

  • When one of your parts is downloaded as a CAD model and included in a design it is identified by your part number and can later be purchased. If the CAD model is edited it may no longer be the same part that you supply and that could lead to all sorts of problems in the design. Therefore visibly having it as a non-native part within the design discourages accidental editing or changing of that part.
  • As well as interchange between CAD systems, standard formats stopped users from being locked into particular CAD systems because all their data was in a that system’s proprietary CAD format. Today, all major CAD vendors support the standard exchange CAD formats (and often other CAD systems’ proprietary formats) so you can access your models in various formats. However, some CAD download solution vendors still create your models in their own proprietary CAD systems and in CAD formats which no other CAD systems read. So when you select a CAD Download vendor ensure you have access to your master CAD models (which may be parametric) from any CAD system you may choose to use in the future!

Therefore the answer to the title question, “Do CAD download file formats matter” is YES and NO!

YES, the CAD format used to build and maintain your master CAD models matters – today you can and should choose an OPEN rather than a CLOSED solution that doesn’t lock you to any one vendor.

NO, the CAD format for importing CAD models into new designs doesn’t matter any more – they can all work and the majority of users are capable of using many of them.Importance of CAD download models to designers

In conclusion, as the CAD designer survey graph shows, the most important thing is for your website to offer CAD model downloads of your parts. The second most important point is future portability of your CAD models by ensuring they are built in a commercially available CAD system. Least important are the CAD formats of the downloads to users because today’s leading CAD Systems import multiple native and standard formats.

That’s what we think, but please tell us what you think?


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