Assembly Planbook - June 2008 - (Page 29)

strength, and offer excellent chemical and temperature resistance,” adds John Lafond, market development manager for appliance and electric motors at Henkel Technologies (Rocky Hill, CT). “As a result of these advancements, appliance manufacturers are using structural adhesives to replace or augment rivets, bolts, welding and other traditional methods.” Numerous Applications Structural adhesive is now a viable option when assembling large appliances. It is used to attach reinforcement ribs in the corner of large sheet metal assemblies, such as dishwashers; bond refrigerator shelf assemblies; attach dryer drum assemblies; and bond retaining gears to shafts for washing machines. Appliance manufacturers use acrylics to bond stainless steel brackets used in electric and gas ranges. Methacrylates are used to bond plastic inner liners to metal frames and metal doors and frame joints in refrigerators and freezers. Acrylics are used to bond compressors to pans. When assembling clothes washers, manufacturers use methacrylates to bond and seal console panels and drum casing covers. Acrylics and epoxies are used to bond door windows to door frames of front-load washers and dryers. Other common applications include electronic components, control panels and motors. For example, magnets are often bonded to electric appliance motors. Epoxies, both one- and two-part types, have traditionally been used for motor assembly. But, newer technologies, such as acrylic-based products, are used at an increasing rate because they set and cure rapidly without heat. “Older appliance motor technology involved the use of clips and other mechanical means to fixture magnets,” says Robert Wallach, technical manager at National Adhesives (Bridgewater, NJ). “High-strength adhesives have all but replaced that method of assembly. Efforts to increase productivity have also led to the use of fast-curing acrylic adhesives for magnet assembly within the electric motor.” Wallach claims there is an increasing amount of bonding and sealing done on household appliances today. Of course, many adhesives are used for nonstructural applications. For instance, as the electronic components of appliances become more complex, many devices are encapsulated with epoxies and sealants to protect their circuitry against heat and moisture. But, engineers are also finding more uses for structural adhesives. “The replacement of spot welding with adhesives is gaining more acceptance than five year ago,” explains Harry Arnon, president of Hernon Manufacturing Inc. (Sanford, FL). “More joints are being designed for structural adhesive bonding instead of spot welding. This design modification will increase the usage of structural adhesives within the appliance industry.” Although many new adhesives can be stronger than traditional joining methods, screws, bolts and rivets still remain popular with appliance engineers. “Fasteners often allow for disassembly and removal of components,” Faced with rising prices, many appliance manufacturers have been forced to use thinner sheet metal. Photo courtesy Indesit Co. The appliance industry continues to use more plastic components. This dishwasher features an adjustable basket mechanism that is made from nylon. Photo courtesy DuPont Engineering Polymers www.assemblymag.com June 2008 / ASSE M B LY 29 http://www.assemblymag.com

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Assembly Planbook - June 2008 Contents Editorial Bonding Lines Quality in Assembly Assembly Lines Assembly in Action Fastening or Bonding? Loose Lips Sink Assembly Systems DFMA Cuts Downstream Costs Robots Lend a Hand Products Advertisers Index Classified Leading Lean

Assembly Planbook - June 2008

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