Feature Distribution
The Model World of 3D CAD
David Pike at RS Components explores some of the basic differences between ‘feature-based modelling’ and ‘direct modelling’ tools, and also what RS is doing to help engineers with the easy availability of component 3D models
E
lectronics engineers need to be thinking more in the third dimen- sion of space and not just the two- dimensional PCB footprint to deliver space-saving designs. The addi- tion of electro-mechanical components for extra connectivity for example can make a substantial difference to what was initially a low-profile design in the early concept phase, potentially introducing significant delays in time- to-market and additional costs. Clearly, this is where the use of 3D CAD tools can reap dividends for companies of all sizes, bringing enhanced productivity and significant time-to-market benefits. But it is not uncommon to find engineers using 2D CAD tools or even paint packages for engineering design, in addition to simply using pen and paper. Looking at the 3D CAD software tools market today, there are options available from many vendors including SolidWorks and AutoDesk. However, it is reckoned that approximately 25 million engineers globally would benefit from using 3D design software, as only one million CAD seats have been sold in total across the major CAD software vendors. Unfortunately, it seems, there have been a couple of major barriers that have meant the use of 3D CAD in the engineering environment has not been as widespread as it might have. Certainly cost is a factor: the price of most 3D CAD tools is high. The latest 3D CAD tools from leading vendors are in the range of $5000 to $30,000 per
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licence, and usually come with high- priced annual subscriptions. Another barrier is the significant learning curve sometimes associated with traditional 3D modelling. Entry- level users may take anywhere between 6 and 18 months before they become fully productive with an advanced 3D CAD tool.
Often, this can lead to CAD designs being outsourced to a CAD specialist company, which can introduce bottle- necks in product development with the processing of even simple changes in the design taking many weeks.
Feature-based modelling The 3D CAD tools that have historically led the market for the past 25 years or so have been ‘feature-based’ CAD tools. This dominance has essentially been a result of the limits of processing power delivered by computers back in the 1980s – whereas the computers of today are some 100,000 times more powerful in comparison.
Because of this lack of number- crunching performance, at the time at least, feature-based modelling held the advantage over other potential techniques – such as direct modelling for example – in that it broke down the construction of the geometry into indi- vidual steps or features, enabling the software’s ability to create and work with complex models.
In the ‘feature-based’ modelling tool, it leads to the creation of a ‘his- tory-tree’, which comprises what are known as ‘constraints’, which in turn
RS Component’s ModelSource component library offers 3D models from 55 different manufacturers available to
download for free
basically describe the relationship between the individual steps or features.
However, because of the computing power now widely available, direct modelling is staking a serious claim as an alternative technology, and in a way it does not really compete directly with the feature-based tools.
One large advantage for direct modelling is that it is generally more intuitive and very easy to learn for non-CAD specialists. Direct modelling technology has been described as being like modelling with virtual clay. In essence, the tool works at the base geometry level and dynamically changes any requested modifications into geometry.
Another advantage offered by direct modelling is greater interoperability, whereas proprietary feature-based sys- tems have incompatible data formats. The direct modelling approach also allows quick iteration on concepts, whereas traditional CAD can often be a cumbersome approach when concep- tualising new ideas in response to RFQs (Request-for-Quotation). However, it is not just the 3D CAD tool that is important. An absolutely crucial piece in the jigsaw for the electronics and electro-mechanical engineer is a product or component model library. Around three years ago, RS created access to an extensive library of 2D and 3D models down- loadable completely free-of-charge as part of its initiative with DesignSpark, building up a community of developers to share open-source designs and ideas, in conjunction with the launch of DesignSpark PCB tool, which is free for engineers to download.
David Pike is Mechanical Applications Manager at RS Components
Now called ‘ModelSource’, this component library contains more than 80,000 component schematics and PCB footprints of semiconductors, passives and electromechanical com- ponents from leading manufacturers. In terms of 3D, this platform also offers more than 36,000 3D models from 55 manufacturers covering key technolo- gies including electronics, electro- mechanical, mechanical, pneumatics and automation and control. RS has recorded more than 440,000 downloads of 3D CAD models. The company is also introducing an addi- tional 1000 models every month from both new and existing suppliers. 3D CAD is undoubtedly going to become an increasingly important tool in our industry, and the distributor is continuing to make significant steps in this area by providing the tools to help design teams get to market more quickly. RS’ 3D page is available now on the company’s website. RS Components
www.uk.rs-online.com Enter 200
SEPTEMBER 2013 Electronics
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