Production of an Artificial Knee Joint

2048 WordsFeb 1, 20188 Pages
Production of an artificial knee joint begins with investment casting, a process that involves little to no shearing. Investment casting produces products that have good surface quality and high spatial accuracy. It is advantageous for parts with more complex shapes or materials that are difficult to form. This method involves seven steps and results in the preliminary shapes of the femoral and tibial parts. 1. Wax Pattern Production Wax patterns function to shape the cavity within the mold. Though it is called a wax pattern, the pattern may also include materials such as wax, stearic acid, plastic and other industrial chemicals [3]. There are two ways to produce a wax pattern. For both, a wax cylinder is first taken from heat preservation equipment and placed on a hydraulic die-casting machine to remove any air or geocerite from the wax. In one process, the wax is then poured into the mold and swirled around until the inner surface is covered with an even coating. This is repeated until an appropriate thickness is reached. The second method is to pressure-inject the liquid wax into an aluminum mold. The mold is then turned upside down so the liquid wax is removed and the remaining wax layer is left to cool and harden. 2. Wax Pattern Assembly In order to improve productivity, workers usually assemble multiple patterns on a holder made of wax. They are held together with melted wax, producing a “pattern tree” so that many wax patterns can be made at once. Patterns with
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