As today’s products become more and more complex—from both a design and functionality standpoint—the accompanying highly detailed product models become very complicated as well. These models are often composed of extremely large assemblies that add great complexity to the design process. Fortunately there are advances, both on the software and hardware sides, that are helping companies cope this with the challenges of designing in context with so many pieces and parts.
The Challenges
Large assemblies can choke PCs and test the patience of engineers waiting for these gargantuan files to load into their CAD software. In a recent industry study, over 40% of respondents say they often experience excessive delays in loading and then interacting with large assemblies.
No longer just geometric representations of products, these mammoth-size models are also often packed with associated product data (metadata, specifications, material properties, manufacturing options and cost estimates), making them identical digital representations of the real-life product. As such, engineers can perform stress, thermal, fluid flow and electromechanical simulations on them as if they were physical prototypes.
While there have been significant advancements in software and the speed and power of today’s workstations, this issue is still quite common for design engineers in the automotive and heavy equipment industries, among others. With part counts ranging from 10,000 to hundreds of thousands, large assemblies quickly overcome the limits of workstations.
According to a new whitepaper by CIMdata entitled, “CAD Selection Considerations: Product Assemblies,” users often resort to workarounds to compensate for unresponsive CAD software. Unfortunately these shortcuts can potentially lead to an increase in design errors that generate downstream problems in the product delivery process.
The Soft Side
There have been several advances on the software side of the equation that have made it easier for engineers to work with large assemblies. Filtering or selective loading is one option for users. It enables engineers to load a subset of their data that provides the context, and go to work on it immediately, or filter what they want to load by size, internal/external parts, or using other rules.
Most CAD programs now offer the option of opening large assemblies without some of their internal components, or with reduced level of details, greatly improving the model response by reducing memory overhead. This works well when engineers simply need to inspect the assembly visually or examine its outer surface or structure.
PTC’s Creo Parametric boasts improved visualization of large assemblies, thanks in part to the 64-bit Windows operating system, which offers more addressable memory for CAD. The company has also borrowed lightweight visualization technology from its annotation and viewing app, Creo View, and incorporated it into its main CAD line.
Here’s how it work: when engineers look at models from an overall perspective, the software doesn’t load all the data, just the graphics and structure. When they zoom in for a more detailed view of a specific area, it begins to load the geometry and feature histories for that part of the model.
The Hard Side
The larger and more complex an assembly becomes, the more computing resources it takes to manage it so engineers should make sure their workstations are up to the task. Beefing up your computer’s RAM is one place to start. Users must be sure that their workstations’ RAM exceeds the minimum requirements of their CAD application. Shoot for anywhere between 8 GB and 16 GB. Other factors, however, also weigh in, such as the speed of your hard drive and your graphics card bus.
The additional processing power available in multi-core processors might eventually come into play, though most CAD programs are still single-threaded. Multi-processors could help by speeding up the display, retrieval and navigation of large assembly structures, but until more software is written to take full advantage of the multiple processors, the promise remains unfulfilled.
While there are strategies that help engineers when dealing with large assemblies, it will require the concerted efforts of both software developers and hardware providers to stay ahead of the tide of demands of engineers tasked with designing today’s increasingly complex products.
