Naim Audio, creating a high-end audio component with SolidWorks

Solution:

Use SolidWorks Flow Simulation software to model the airflow through the component and guide modifications that promote passive cooling.

Results:

· Reduced prototyping from as many as 10 prototypes to 2

· Final design is self-cooling up to 25° C (77 ° F)

· Hard drive manufacturer validated all analysis and testing results.

All of Naim’s products receive the same care in design and engineering, from a $30,000 CD player to the $4,000 Naim Uniti all-in-one unit. In designating Naim Uniti the best product in its class for 2009, Tone Audio magazine observed: “Naim  has packed the heart and soul of their famous NAIT 5i and CD5i onto one chassis, no cheesy class-D chip amps here.”

Naim has a policy – expressed on its Website – of not creating a new product “unless it has something genuinely new to offer and integrates perfectly into our product range.” In 2008, the sales and marketing departments decided that a hard disk player met that standard.

New product, new design challenge

Hard disk players store digitized music and play it through stereo systems. A hard disk player is just another stereo component in most regards, but the hard disk player had a complication that Naim’s other components didn’t. The hard drive itself. It presented one of the biggest challenges that Naim’s 30+ person design team faced in producing its hard disk player (HDX): how to keep the component cool enough to prevent the hard drive from failing prematurely. Naim products are sold worldwide in a variety of climates, so the HDX had to resist overheating even in tropical temperatures.

“We had to be very conscious of the temperature inside the unit. Hard drives have a temperature they like to turn at, and it reduces their life expectancy if they run too hot. The bearings wear out, for example,” said Naim Audio Mechanical Design Manager Paul Neville. “The HDX was our first product with a hard drive, and it also has significantly more software than anything else we’ve designed. A complex product means more electronics, and more electronics generate more heat. At the same time, they reduce the amount of room in the unit that allows heat to circulate through. We had to do a lot of thermal analysis before we went to market to make sure the unit wouldn’t overheat.”

Guarding against overheating required even more analysis than Naim Audio usually devotes to a new product, Neville said. Also complicating the task was Naim’s desire for the internal fan to operate only at extreme temperatures, not at regular room temperatures.

“We wanted the HDX to operate at ambient room temperature without the fan kicking in, so it had to be passively cooled,” Neville said. “That meant incorporating heat sinks into the design and using positioning of the interior components to promote airflow through the product.”

SolidWorks analysis provided fast answers

Naim has designed and analyzed its products using SolidWorks CAD, Simulation, and Product Data Management software since Neville came to the company 3½  years ago. He had worked with SolidWorks and a competing product in his previous job. Based on Naim’s size and its analysis requirements, he recommended switching to SolidWorks because of its integrated analysis tools and cost effectiveness. Also, because of SolidWorks’ growing footprint in the engineering community, Neville said switching to SolidWorks gave Naim access to a bigger talent pool to hire from in the future.

“We design all of the physical elements of our products in SolidWorks, except for PCB boards. We do those in a specialized PCB application then convert the results into a solid model. For everything else – chassis, knobs, buttons, connectors, internal components, cable accessories – we use SolidWorks CAD software. To validate our designs, we use SolidWorks Flow Simulation.”

Neville’s team used SolidWorks Flow Simulation to model the heat flow through the HDX. Flow Simulation enabled the Naim team to analyze:

• radiation heat transfer between high-temperature surfaces;
• heat flow between and around components;
• transient flow analysis for simulating unsteady flow over time;
• conduction and convection heat transfer.

HDX was the first time Naim used SolidWorks Flow Simulation in new product development. Designers used a CAD model of the HDX as a starting point to create a thermal analysis model in SolidWorks Flow Simulation. The model enabled them to predict the flow patterns and maximum temperatures inside the HDX. Designers modified the CAD models in response to the thermal analysis, then ran another analysis to ensure the modification would work.

“The SolidWorks Flow Simulation software worked very well at giving us comparative solutions,” Neville said. “For example, if we changed the material or thickness of a heat sink, we would run another analysis to see what effect that had on key components. Otherwise, we would have had to use physical prototypes, and that would have taken a lot of time. We ended up doing two prototypes to look at the thermal side of the design, but using the software we tried 10 different scenarios. If not for the software, we would have needed 10 prototypes.”

Neville said SolidWorks Flow Simulation’s ability to clone a project to compare two versions side-by-side and the setup wizards for starting tasks also helped cut time off the design process.

Analysis yields self-cooling product

Using SolidWorks Flow Simulation results as a guide, Naim settled on a design that includes a 5mm thick aluminum product case that provides a built-in heat sink for the components and a path to remove heat from product. Components were mounted to the case so their heat would radiate out of the product. Designers moved the primary hard drive close to the cover to shorten the path heat had to travel to get outside. The internal air flow keeps the fan off unless the temperature rises above 77 degrees.

The HDX went to market in late 2008 to praise from the audiophile press. “We didn't expect to be won over by a computerized box of tricks, but we have been,” said TechRadar U.K.

“Naim Audio, a name synonymous with high-end, has recently launched its very own hard drive-based music server, and on paper, it's a fairly mesmerizing piece of kit,” wrote Engadget.

Neville said Naim sent the HDX to hard drive manufacturer Seagate’s test center before it went into production, to double-check its test results.

“They confirmed all of our analysis and testing,” he said. “It’s a testament to how intuitive the SolidWorks Flow Simulation software is that we were able to achieve results like that our first time using it.”

For more information about Naim Audio’s HDX visit www.naimaudio.com