You May Not Need a PDM After All
Michael Alba posted on December 06, 2019 |
Why Onshape believes data management should be built into CAD.
PDM systems are important, but imperfect. Onshape says it has a better way. (Image courtesy of Onshape.)
PDM systems are important, but imperfect. Onshape says it has a better way. (Image courtesy of Onshape.)

Onshape has sponsored this post. 

Do you care about how your CAD data is stored? Actually, let’s rephrase that: Do you want to stop caring about how your CAD data is stored?

Today, many design engineers use product document management (PDM) systems to keep track of the hundreds, thousands, even millions of CAD files created during product development. PDM offers a way to organize this avalanche of data, and even more importantly, a way to control it. The bigger a design team and the more CAD data generated, the greater the need for strict control over who can access and edit which data and when.

The need for PDM became apparent as CAD came to dominate product design, so many PDM systems are now sold alongside their CAD counterparts. There are also third-party PDM systems available, and some organizations create their own systems to manage their CAD documents. Whatever the specifics of the system, PDM is better than nothing (and much better than Windows File Explorer).

However, PDM systems are not typically well-liked by end users. PDM can feel like a bureaucratic chore that gets in the way of a designer’s real work. And for all their efforts to keep CAD data under lock and key, PDM systems share inherent flaws that can work against this goal.

Perhaps there’s another way. Onshape, the cloud-based CAD system that was recently acquired by PTC for $470 million, believes that stand-alone PDM systems are the way of the past. Not that you should revert to manually searching through a mile-high stack of design files. Rather, what if you didn’t have files at all?

In this article, we’ll explore how Onshape believes it’s found a better way to manage product data.

PDM: Useful, But Flawed

PDM exists for a reason. Without it, design files would routinely be lost to the ether, copies would multiply like rabbits, conflicts would abound, and engineers would never know for certain if a file was up to date. These are big problems that can cost time and money, and delay product launches. A recent survey from found that 71 percent of product designers lose time because they accidentally used incorrect versions of design files.

How does PDM attempt to solve these problems? Essentially, PDM is an index of all your CAD data. It knows where files are located, understands which files are interdependent, and records earlier versions of files. It’s essentially data about data. But more than that, PDM systems are gatekeepers of data. If you want access to that data, you have to go through PDM first.

To edit a model, you first have to request the file from the PDM system (called a check-out). While you’re editing the file, no one else will be able to work on it—they’re forced to wait until you have checked the file back in. While this prevents multiple designers from unintentionally creating conflicts, it also bottlenecks a design by enforcing a serialized workflow.

As long as files remain locked in the PDM system, they’re stable. But as soon as a file is checked out, it can be copied and distributed endlessly. Let’s say, for instance, that an engineer checks out a file, emails it to a contractor, and checks it back into the PDM system. Now there are several copies of the file (one in the system, one on the engineer’s hard drive, one on his email server, one on the contractor’s email server, and one on the contractor’s hard drive). It would be very easy to mistakenly edit one of the copies. For example, the contractor might make a tweak to the file and send it back—but in the meantime, the PDM system file has been checked in and out by several other engineers. In this scenario, there’d be two conflicting versions of the file, despite PDM’s best efforts.

Has this ever happened to you? (Image courtesy of Onshape.)
Has this ever happened to you? (Image courtesy of Onshape.)

There are many further upsides and downsides to PDM that we don’t have time to cover in detail here. But perhaps the main problem with PDM is that it places an unnecessary burden on engineers. To constantly have to worry about checking files in and out can create mental overhead that could be better spent on designing.

How Onshape Manages Product Documents

Many CAD providers have begun to incorporate the cloud into their PDM systems. However, most of these implementations simply replicate the problems of local PDM systems. For instance, to check out a file in a cloud-based PDM system, you still must download that file from the cloud, and the cloud system will still lock other users from editing it.

Though Onshape is a cloud-based CAD system, it takes a fundamentally different approach to design data. Onshape doesn’t use files in the classic sense of the word. Rather, Onshape is built on top of a nonrelational database, and any changes to a design are simply updates to the database. In contrast, traditional PDM systems are relational databases that point to files and their associations with one another. To avoid getting too in the weeds here, this blog post from Onshape goes into much more detail.

The bottom line is that Onshape’s database approach enables a new way of interacting with design data. There’s never a question as to what is the most up-to-date version of a model, because there’s no files associated with that model—it’s just data in a database. For the same reason, multiple designers can edit the same model at the same time without ever causing conflicts. Best of all, users never have to check files in or out, because there are no files. Onshape’s database approach obviates the need for a separate PDM system—in a sense, PDM is built right in.

“Onshape is the first and only professional 3D CAD system where the CAD system and the CAD data live in one place in the cloud,” Onshape CEO Jon Hirschtick wrote in a blog post. “Neither the CAD system or the CAD data are ever copied anywhere. There’s no problem finding the latest version because there is only one place to look.”

PDM Without PDM

Keeping files organized and controlled is just part of a PDM system. PDM should facilitate product development with customizable approval workflows, automatic part numbering, advanced search filters, version control, real-time analytics, security features, collaboration tools, and more. A nonrelational database doesn't automatically engender these additional features, but you'll find them all in Onshape--the company has focused a lot of its development energy toward better design data management.

Example of real-time analytics in Onshape. (Image courtesy of Onshape.)
Example of real-time analytics in Onshape. (Image courtesy of Onshape.)

One of Onshape’s most interesting data management tools provides the ability to create branches of a model, similar to branching a Git repository. For example, you could create a test branch to experiment with a new idea while leaving the master model untouched. If you’re satisfied with your experiment, you can merge the branch back into the main design. This feature also enables designers to work on multiple engineering change orders at the same time, rather than enforcing the serial workflow that’s necessary with most PDM systems.

Every single update to a model is recorded in the Onshape database, allowing unlimited undos and redos. This record also allows for detailed analytics. Project managers can see exactly who made what changes and when, with updates occurring in real time. They can add and revoke user permissions as necessary. Additionally, they can share data with suppliers and contractors using a link, not an email, so there are never any unsecured copies.

Example of branches in Onshape. (Image courtesy of Onshape.)
Example of branches in Onshape. (Image courtesy of Onshape.)

Onshape occupies a unique position in the CAD landscape as the only platform that’s entirely in the cloud. While other CAD platforms make use of the cloud, they do so in ways that necessitate files, and those files necessitate separate PDM systems. With Onshape’s approach to managing design data, there are no files, so there’s no need for a separate PDM system.

But recognizing the value that PDM provides, Onshape still provides data management features like versioning, approval workflows, analytics, and more. For more information on data management in Onshape, visit the Onshape website.

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