Appliance Design - November 2007 - (Page 33)

QUALITY & STANDARDS At Material Sciences Corp., a front loading clothes washer undergoes acoustic testing. nies who turned to Lyon for help in dealing with noise and sound issues was a maker of vacuum cleaners. “Everybody knows that vacuum cleaners are very noisy and people in general object to the sound,” he says, “but it is also true that people judge the power and the cleaning ability of a vacuum cleaner by the noise it makes. The question is how can the OEM possibly win?” For the manufacturers of this appliance, the path toward a winning solution started by finding an acoustic expert — Lyon — to test the product, explain the conundrum, and find a way to make a product that is quiet, but not too quiet. Or, to put it another way, quiet the part of the noise that is annoying, while keeping the sounds perceived as reassuring of the product’s performance. As it turns out, consumers think the vacuum cleaner does a good job when they hear airflow from the nozzle where it meets the rug, but are annoyed with the noise created from the main suction fan and the motor cooling fan. By redesigning the components, including tweaking the impellers, the annoying sound was reduced and was masked by the less annoying sound from the nozzle. From an OEM’s point of view, finding and fixing suspected noise problems can be pivotal in a marketplace where products are sold as being “three decibels quieter” than their competitor’s. In some cases, municipalities and other regulatory agencies address the noise issue from a comfort and health perspective. Many cities, for example, have laws regarding the operation and noise levels of www.applianceDESIGN.com leaf blowers. But, as in the vacuum cleaner example, noise problems are not always easy to find or fix. Appliance manufacturers face a number of potential noise sources including fans, compressors, pumps and motors, some of which have intermittent operation. The vibrations from these components resonate off of nearby support columns and stamped parts, creating the noises that grate on nerves. Acoustic testing facilities offer OEMs the expertise and the state-of-the-art equipment that is used to track down noise and suggest ways to civilize it. But how do designers go about finding the best lab for their needs? Determining what lab to choose is not simply a matter of going to the NIST Web site and finding a list of certified labs, although that is a good resource. (For details, visit http:// ts.nist.gov/Standards/scopes/acots.htm) The manufacturers first need to determine their objectives, says Kevin Herreman, program leader for the Owens Corning Acoustic Testing Center, Granville, Ohio. The objectives may range from simply reducing overall noise levels, to improving sound quality, and may include providing technically accurate marketing materials or meeting governmental and industry standards. The objectives then logically lead to essential testing procedure questions. Will the product as a whole be tested, or will tests be conducted only on noise-producing components? Will the product be tested in an anechoic chamber or in a simulated end-use environment? A clothes washer undergoes testing in a reverberation chamber at Owens Corning. Acoustic holography is used by Owens Corning researchers to test where noise is emanating from an automobile. applianceDESIGN November 2007 33 http://ts.nist.gov/Standards/scopes/acots.htm http://ts.nist.gov/Standards/scopes/acots.htm 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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