How to maximize the impact resistance of molded medical components

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In order to determine how long the plastic can be exposed to UV cured adhesives before the properties start to diminish, a study was completed involving Makrolon 2458 polycarbonate and several UV adhesives from different manufacturers.

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Polycarbonate medical parts in multi-use sterilization applications are exposed to more potentially damaging sterilization treatments and longer exposures to potentially aggressive substances than single-use devices. Multi-use parts, therefore, need to be more durable. Improvements in specific areas of part design, along with adherence to good molding practice, can produce better parts for multi-use applications.

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Designers can successfully design premature failure out of plastic parts and assemblies by giving proper consideration to proper part design.

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As the usage of engineering plastics increases, more attention has to be paid to the structural and functional design of the molded parts to avoid expensive field failures. Experimental stress analysis aptly fills the gap between theoretical stress analysis and failure analysis.

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Gas-injection technology (GIT) provides a unique means of manufacturing plastic parts, many of which could not be produced through conventional injection molding. The process opens up new possibilities in terms of design flexibility, metal replacement potential and cost/weight reduction. This paper centers on elements of design, processing and material selection that differ from conventional injection molding.

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Multi-component molding is one of the fastest growing trends in injection molding. This technique provides the ability to mold sophisticated end products of two or more materials, while reducing several molding processes to a single molding cycle on one machine. Multi-component technology has tremendous benefits, including high cost savings and quality improvements in parts. Many medical applications already include multi-component techniques and combine thermoplastic urethanes (TPUs) and polycarbonate (PC) or polycarbonate blend (PC/ABS) resins. The objective of this paper is to examine the chemical adhesion between two dissimilar materials by studying the effects of processing on adhesion.

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Methods for manufacturing hollow-cored plastic components, such as manifolds, are now in a position, both technically and economically, to replace current metal designs. The multishell technique, when properly utilized, provides the simplest and most economical approach to manufacturing these high-quality, hollow-bodied components.

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The finite element technique is a well-established tool to aid the engineer in optimizing a design. For many cases, linear analysis is sufficient when dealing with plastic materials under low level loading. However, for some problems such as snap fits, buckling, impact, high loadings, etc., nonlinear analysis is necessary. The engineer must recognize the limitations of linear techniques and understand how to deal with nonlinearities. Proper use of nonlinear techniques may allow for a wide range of material options and provide added flexibility and confidence in a design.

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This paper presents an assembly of two hypothetical medical device parts that have several problems stemming from improper design. It is relevant to all plastic part designs.

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This paper focuses on the use of plastic/metal hybrid technology in the design and development of an instrument panel support beam. A roughly 40% weight reduction with the use of 7 fewer pieces, a 10% lower cost, and lower investment are among the advantages. This technology can be applied in other non-automotive applications.

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Polyurethane structural foam has been utilized in a wide variety of market applications because of its unique range of performance benefits, such as low-density molding, thickness variations, encapsulation, large part capability, and in-mold paint finishing. This paper briefly reviews the processing parameters used to mold rigid PUR structural foam, offers some design considerations, and describes a simple method used to derive material properties necessary to analyze the load-bearing performance of the integral PUR sandwich. An example is provided which shows predicted results versus actual performance.

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Solvent stress testing is a proven method for identifying areas of elevated stresses in parts and assemblies made from polycarbonate. The testing usually involves immersing molded samples in stress-cracking solutions for 3 minutes at room temperature. The samples are then promptly rinsed and inspected for signs of stress cracking. The presence of stress cracks indicates that the stress level in the part exceeds the stress threshold for that test.

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