Preformed liners

Film or preform adhesives are produced by casting the premixed resin and hardener onto release liners. Single or multiple master batches of the resin mixed with the... 

In the WIAM process, the UHMWPE sheets or blocks are first machined into preforms (for acetabular liners) or slabs (for tibial inserts) and placed on a conveyor within an oven maintained at a temperature just below the melting temperature of the polymer (approximately 125°C). The warm UHMWPE pucks are exposed to a 10 MeV Rhodotron electron accelerator, which deposits... 

A loose bolt type of fitting for the liner anchors would not be acceptable to liner designers because it would depend on a nut and washer to seal the preformed hole in the liner. Liner anchors penetrating and projecting from the liner face would not be acceptable either since the resultant thickness of liner around the perimeter of the preformed hole is only the thickness of the fillet weld to the anchor rod. The detail could be... 

With this method, the extruder also works continuously, but the melt is stored in a tubular piston accumulator (Figure 1.139) from which the plastic is intermittently extruded to produce the tubular preform. Figure 1.140 illustrates an extrusion blow molding machine equipped with an accumulator head as it is used, for example, in the manufacture of plastic fuel tanks, barrels, liners, and other similar large structures. The removal of the finished part is done with grippers and a transfer mechanism. The accumulator heads work best with the first in, first out (FiFo) principle. This is necessary in order to accommodate for the limited thermal stability of the plastic. 

SiC whiskers also can be combined with metals to increase the high-temperature strength of the material as well as provide a comparable substitution for heavier traditional materials, such as steel. Metal-matrix composites (MMCs) are being tested for such applications as piston ring grooves, cylinder block liners, brake calipers and aerospace components. MMCs can be fabricated by infiltrating an SiC whisker preform with aluminum or by the addition of SiC whiskers to molten aluminum. 

An interesting design application is the forming of inner door panels for automobiles. First a loose, coarse mat of wood fibers and phenolic resin is thermoformed— stamped in warm molds at 250-350°F. This wood/resin composite preform then serves as the mold for the next process—vacuum forming of a vinyl plastic skin over the wood liner. The composite preform is porous and permits pulling of the vacuum directly through it as shown in Figure 10.10. 

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