Appliance Design - November 2007 - (Page 34)

QUALITY & STANDARDS A semi-anechoic chamber at Material Sciences $15 million acoustic research facility. Do particular tests need to be done such as those from ANSI, OSHA or the European Union, which often require data to be how the human ear will respond? For that matter, what test data is required? Are sound level measurements desired on the standard dB scale, or are they preferred on the A-weighted dBA scale? (A-weighting refers to a standarized means of measurement adjustments that take into account the fact that our hearing is more sensitive to some frequencies than others. So perceived loudness is not the same as actual sound intensity.) Once noise sources are identified, further questions must be posed as to how to deal with it? Do parts need to be redesigned or respecified? Or can the situation be handled by either isolation or damping methods? If damping materials are to be employed, which ones are best for targeted frequencies, where are they optimally applied, and in what quantity and thickness? And, most importantly, will they do the job? Proving out the noise-reduction capability of materials is one reason that in 2006, Material Sciences Corp. of Elk Grove Village, Ill., opened a $15 million, state-of-the art Application Research Center in Canton, Mich., featuring sophisticated acoustic testing chambers and equipment. The facility tests appliances, as well as automobiles and other products, to determine if its sound damping materials such as Quiet Steel, MagnaDamp and SoundTrap can be employed to tune down unwanted noise. “The OEM can find out the exact benefits they can receive from these materials,” says Mark Gresser, vice president of sales and marketing. “That burden had previously been on the OEM to do the actual testing and proof.” Gresser adds that OEMs searching for an acoustic laboratory must be confident that the results are fair and not fudged one way or the other. “We have taken great pains to be scientifically accurate and as neutral as possible so that when we say that Quiet Steel will work great for you, it is not just that we are trying to sell a product.” Dan Eigel, general manager, OEM Products, at Owens Corning, says that being independent is a critical consideration for his lab. He adds, however, that having the ability to determine the cause of noise in the lab and deliver the means to solve the problem is something that many OEMs find appealing. Owens Corning, like MSC, will suggest a material solution involving their materials to dampen sound. Acoustic testing labs can do many different jobs. MSC’s technology center for instance has the capability to analyze individual components and entire units in sizes ranging from the small, such as a disc drive, to the large, such as a truck. It features acoustic array holography capabilities, and fully and semi-anechoic (quiet) chambers, and reverberation rooms, that have all of the needed hook-ups for repeatable and real world analysis and testing includA microphone array at MSC's test facility captures sound levels in an anechoic chamber. Below this room, noise is generated and the microphones measure the decible levels that filter through the component, which is inset into the floor. ing water, gas, and electric hook-ups for all product types. Using state of the art facilities and computer aided engineering and simulation software, the three main parameters that drive noise and vibration problems — temperature, frequency and part design — are identified and the recommended solutions are developed. The anechoic chambers — literally rooms that do not echo — feature walls made from wedges of fiberglass foam. The rooms are isolated so that it is incredibly quiet and the wedges will absorb the sound waves and reflect almost no waves back. “The purpose of this type of room is to simulate the outside world but without any extraneous noise,” says Alan Hufnagel, NVH Technical Manager for Material Sciences Corp. “The room is so quiet it is at the threshold of hearing. If you have a microwave oven in here, any sound that it makes will be recorded without any extraneous sound interfering.” Hufnagel adds that if testing for noise, rooms such as this give the researchers a repeatable and controlled environment. For additional testing purposes, a reverb chamber is located underneath the anechoic chamber and here noise is generated. A stamping can be fixtured to a “window” in the floor of the anechoic chamber. In the reverb chamber, loud speakers can blare noise and the researchers can measure the noise levels that are coming through the part. These rooms can also help isolate where noise is coming from on an appliance, says Herreman, whose lab also features anechoic and reverb chambers as well as the acoustic holography technology. Herreman says that the microphones placed strategically around the test object 34 applianceDESIGN November 2007 www.applianceDESIGN.com http://www.appliancedesign.com

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Appliance Design - November 2007 Contents Editorial Shipments/Forecasts News Watch Today’s LEDs are Brighter and More Colorful than Previous Versions, Allowing Designers More Opportunities to Improve and Differentiate Their Products. When Converting from CCFL to LED Backlights in LCD Panels, New Driving Methods are Needed. Electrowetting Technology Allows Displays to be Designed in an Extensive Range of Colors. Noise Problems are Not Always Easy to Find or Fix, but Acoustic Labs Can Help Designers Ferret Out the “Good” Noise from the “Bad.” A New Sanitization Protocol for Clothes Washers Combines the Best of Three Well-Established Provisions to Ensure Efficiency, Quality and Safety. Stricter EMC Requirements Raise the Bar for Appliances with Electronic Controls and Require Testing to New Levels. Despite Added Cost and Complexity, Gas-Modulating Systems have Migrated from Large-Scale Boiler Applications to Smaller Residential and Commercial Furnaces and Appliances. A New Treatment Technology Hardens the Surface of Light Alloys such as Aluminum and Magnesium and Expands Their Potential Applications. DesignMart Advertiser’s Index Association Report: AHAM

Appliance Design - November 2007

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