Appliance Design - September 2007 - (Page 59) DECORATION specifically been designed for FIM, leading to a condition known as wash out. In particular, problems can occur around the gate area, or the points in each mold through which molten resin is injected and where temperatures tend to be highest. To overcome these issues, special melt-resistant inks, such as thermal-cure, UV-curable or high melt-resistant polymers, are required. Forming represents the second major stage in the FIM process, taking the printed flat sheet to create a three-dimensional shape, prior to final trimming and injection molding. There are a number of methods that can be used, and choosing the right process for each job is important to ensure that print registration and quality are retained. For example, vacuum forming can be carried out at relatively low cost, and it produces shallow and deep drawn parts, and is capable of handling large area sheets, so that higher numbers of components can be produced during each production cycle. The high temperatures used, however, can lead to distortions that adversely affect areas requiring high print registration tolerances. By comparison, high-pressure forming at lower temperatures can minimize distortion errors, and be used for shallow and deep drawn parts alike, but the high clamp forces required mean that the machines tend to be smaller, so fewer parts can be produced per cycle. A third option is hydroforming, which produces extremely high pressures, so sheets can be molded at low or ambient temperatures, thereby eliminating heat distortion. However, although registration is generally excellent, it is difficult to form anything other than shallow drawn shapes, while harder polymer films have to be used to prevent surface damage from contact with the blanket or bladder. The final process stage is injection molding, and this ideally requires mold tools that have been designed for each FIM component to ensure that high levels of detail and graphics resolution are realized. In addition, the forming or molding tool should be formatted to maximize the number of parts produced in each production cycle, as careful part placement will minimize scrap and simplify subsequent trimming operations. When producing the mold tool it is important to ensure that the wall thickness, especially near gates, is carefully controlled, as thin walls will cause extreme shear stress on the pre-printed inks. Detailed graphics should be kept away from deep-drawn sections and gates should be positioned in areas free of ink. If this proves impossible, then one should use a wide fan gate or a gate that produces an even melt-flow across that area of the component to minimize turbulence, ink wash and shear effects. Designers should also try to ensure that particularly detailed graphics are not included in the gate area. FIM is an exciting and rapidly evolving process that offers considerable opportunities for designers, OEMs and end users alike in a wide range of applications. In a world where manufacturers have to respond faster and more cost effectively than ever before to retain a competitive edge, FIM looks set to become a key tool that delivers value and cost savings while cutting time to market. < For more information, enter number. . . . . . . . 304 Or email: pressrelations@autotype.com NORTH AMERICA’S LEADING & LARGEST PERFORATOR Supplying Perforated Components to OEMs since 1915. Our emphasis on quality, on-time delivery, fair prices and the capability of producing materials in tolerances higher than industry standard has made DIAMOND North America’s leading and largest perforator. Call for our 188 page catalog covering all aspects of the perforating process, material information, company capabilities, tolerances and technical studies data. 2 4 3 W. E I G H T H S T. W YO M I N G , PA 1 8 6 4 4 800.233.9601 W W W. D I A M O N D M A N . C O M For more Information Enter 139 www.applianceDESIGN.com AD04071Diam.indd 1 2/22/07 9:20:32 AM AD10064Triml.indd 1 For more Information Enter 140 applianceDESIGN September 2007 59 9/7/06 2:11:25 PM http://www.trimlok.com http://WWW.DIAMONDMAN.COM http://www.trimlok.com http://WWW.DIAMONDMAN.COM http://www.appliancedesign.com
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