Appliance Design - August 2007 - (Page 41)

JOINING tener does more than just limit the number of versions needed, it also makes it possible to compensate for deviations in the thicknesses of the panels as well as plating thicknesses used. Holding and pull forces vary depending upon the application. Stronger forces such as weight and lateral forces come into play when using a hinge on a door. The layout of the DSNAP fasteners can be designed in various ways to satisfy these diverse requirements. Holding and pull forces need to be absorbed by the fastener with a clamping mechanism. In order to function properly once the D-SNAP elements are in place, it is important that they do not get pushed back into the channel by the forces acting upon them. The layout of the D-SNAP fastener’s defined pitch addresses this issue. A clamping pitch with an angle of 14 Deg or 15 Deg is most effective, as it provides the necessary clamping and exhibits a self-locking effect. This was confirmed during a test where it proved impossible to pull out a D-SNAP fastener installed on a 0.059 in. (1.5 mm) thick panel until the pull force reached approximately 4,500 N. The panel first buckles and the cutout hole enlarges before the D-SNAP fastener comes free. (See Fig. 6.) The height of the D-SNAP elements and the length of the wings are virtually insignificant, as long as an appropriate clamping range has been chosen and the angle of the clamping pitch lies between 14 Deg and 20 Deg. The width of the wings is unimportant, but extra width can increase stability. Wider wings are recommended for thicker panels. The length and the width of the channel play important roles for the forces acting on the panel plane and for the force that could distort the D-SNAP fastener within the panel cutout, but only in an indirect way. Larger D-SNAP fasteners are recommended for heavy doors. In addition to the existing lineup of DSNAP fastener components, more such components using the technology are on the way. There are currently many concepts still under development, including D-SNAP fasteners for round profiles and T-Channels. It will be possible to develop many more such application concepts in the future due to the adaptability of the fastening technology. < For more information, enter number. . . . . . . . . . . 319 Or email: options@dirak.com applianceDESIGN August 2007 41 Fig. 6. In a pull-out test with a D-SNAP fastener in a 0.059-in. metal panel, the fastener came free only when the metal buckled and the cutout hole enlarged (right) at about 4,500 N. depth as possible. Generally, these fasteners can be installed in edge areas and other dead spaces. Minimum installation depth of a D-SNAP fastener is only 0.276 in. (7 mm). As long as the minimum specification is maintained, D-SNAP fasteners can generally be made in all desired user-specific installation depths. The D-SNAP fastener needs to adapt to the thicknesses of the panel for a secure fit. This is true whether the fastener is used to join two panels or to install hardware on a lamping itch Height of the pitch Height of the wings Fig. 5. Proper clamping pitch ensures that the element engages securely. panel. This is achieved by the layout of the DSNAP fastener’s clamping range. (See Fig. 4.) In any D-SNAP element, the clamping pitch, the height of the wing, and the height of the pitch together create a right-angled triangle. The clamping pitch represents the hypotenuse of this triangle. The clamping angle amounts to 14 Deg to 15 Deg. Based on the tangent function, a ratio of the legs of the right-angled triangle of approximately 4:1 results, so that with the height of the wing at 0.157 in. (4 mm), the height of the pitch amounts to 0.039 in. (1 mm). (See Fig. 5.) The height of the pitch of 0.039 in. (1 mm) is, however, not fully utilized for clamping, which allows it to compensate for the various panel thicknesses. At the beginning and at the end of the clamping pitch, approximately 0.008 in. (0.2 mm) of the height of the pitch is intended as a safety clearance in order for the D-SNAP element to engage securely behind the edge of the panel within the area of the clamping pitch. The clamping range of the D-SNAP elements thus lies in the center of the clamping pitch and occupies approximately 0.024 in. (0.6 mm) of the height of the pitch, resulting in an application clearance of ± 0.012 in. (0.3 mm) and a clamping range of 0.024 in. (0.6 mm), within which the DSNAP element guarantees secure bracing. Due to this clamping range, it takes only a few different versions of D-SNAP fasteners to accommodate the variety of panel thicknesses available. The clamping range of the D-SNAP fas- www.applianceDESIGN.com http://www.appliancedesign.com

Table of Contents Feed for the Digital Edition of Appliance Design - August 2007

Contents Editorial Shipments/Forecasts News Watch A Reed Switch is Simople, yet Versatile, and Designers are Finding New Uses for this Time-Tested Technology A Novel Actuation and Sensing Technology can Register a Light Touch, but Resist Blows from a Hammer Tracing the Source of Noise is Made Easier with Noise Source Identification Methods Appliance Noise can be Annoying, but Designers have Many Material Choices to Help Rein in the Racket Nanocomposites are No Longer a Technology for the Future. These Plastic Materials are Already on the Job A New High-Strength, Low-Density Glass-Microsphere Additive can Improve Plastic Part and Molding Performance A New Electromagnetic Weld/Bonding Process Helps Ensure Long-Term Integrity of Joints in Plastic Parts Snap-Based Technology Eases Installation and Makes Products More Serviceable Two-Part Silicone Adhesives Provide a Rapid-Cure Alternative to Traditional One-Part Silicones Classified DesignMart Advertiser’s Index Association Report: GAMA

Appliance Design - August 2007

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