Blow molding injection, insert

Beryllium copper n. Copper containing about 2.7% beryllium and 0.5% cobalt, used for blow molds and insertable injection-mold cavities. The small percentages of Be and Co greatly increase the strength and hardness of the copper whole preserving its high thermal conductivity and corrosion resistance. Beryllium copper is easily pressure cast and bobbed into mold cavities. 

Injection and blow molded products based on inhibited PE and PP produced by the Northern Instruments Corp. (USA) have become world standard for anticorrosion plastic containers. Similar plastic products modified by VCI are manufactured by the German companies Rose Plastic and Brangs and Meinrich [20]. Another original sort of inner packages for small diameter metal tubes is a tube strip. Tube strips are extruded PE tubings inserted into metal tubes to protect their interior surfaces from corrosion [21]. 

Aluminum and beryllium copper are often used for blow molds for plastic bottles. Beryllium copper has better heat transfer and resistance to wear, but is more expensive. Aluminum is used most because it is significantly less expensive and provides good heat transfer, although it does wear more quickly. Because blow molds are not subject to pressures nearly as high as the pressures in injection molding, the molds can be less rugged. Beryllium copper or steel inserts are often used in the parts of the mold most subject to wear, such as the pinch-off in an extrusion blow mold. A typical blow mold can produce about 12 million containers before it must be discarded, provided some refurbishing is done periodically. 

Injection blow-molding requires two molds one for molding the preform or pari-son, and the other for molding the bottle. The preform mold consists of the preform cavity, injection nozzle, neck-ring insert, and core-rod assembly. The blow mold consists of the bottle cavity, neck-ring insert, and bottom-plug insert (see Figs. 6-10). 

In extrusion blow molding, molten resin is extruded into a cylindrical shape called a parison. This parison hangs downward, and then two mold halves close around it. At the top and the bottom of the mold, the cylindrical shape is pinched together, leaving a hollow tube in the middle. A needle is inserted into this tube, and pressurized air is injected into tube, forcing the walls of the tube to stretch and expand outward, until they conform to the mold. Once the material cools and solidifies, the mold is opened and the part is removed. 

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