Beryllium copper cast

Beryllium-copper Cast 5.24 Very good Very good 0.004... 

Table 4. Physical Properties of Cast and Wrought Beryllium Copper Alloys...

The mechanical properties of wrought alloys depend on composition and metallurgical condition. At the extremes, annealed pure copper has a tensile strength of 180MN m and a hardness of 40 Hy, and heat-treated beryllium copper can have a tensile strength of 1 300 MN m and a hardness of 390 Hy. Summaries of typical properties of some of the more important wrought and cast copper alloys are given in Tables 4.9 and 4.10. 

Production molds are usually made from steel for pressure molding that requires heating or cooling channels, strength to resist the forming forces, and/or wear resistance to withstand the wear due to plastic melts, particularly that which has glass and other abrasive fillers. However most blow molds are cast or machined from aluminum, beryllium copper, zinc, or Kirksite due to their fast heat transfer characteristics. But where they require extra performances steel is used. 

The pressed and cast formulations can also be machined afterward if required but this is carried out remotely because of the hazards involved during the machining process. Also, the tools which are used for machining purpose should be of non-sparking type viz. made of brass or beryllium-copper alloy. 

These alloys are available as wrought or cast alloys. The principal wrought copper alloys are the brasses, leaded brasses, phosphor bronzes, aluminum bronzes, silicon bronzes, bciylhum coppers, cupronickels. and nickel silvers. The major cast copper alloys include the red and yellow brasses, manganese, tin, aluminum, and silicon bronzes, beryllium coppers, and nickel silvers. The chemical compositions range widely. For example, a leaded brass will contain 60% copper, 36 to 40% zinc, and lead up to 4% a beryllium copper is nearly all copper, containing 2.1% beryllium, 0.5% cobalt, or nickel, or in another formulation, 0.65% beryllium, and 2.5% cobalt. 

As blow molds do not have to withstand high pressure, a wide selection of construction materials is available. The ultimate selection will depend on a balance of the following factors cost, thermal conductivity, and required service life. The more commonly employed materials for small parts are aluminum and aluminum alloys, steel, beryllium copper (Be/Cu), and cast zinc alloys (Kirksite, etc.). Aluminum molds are excellent heat conductors, are easy to machine, can be cast, and are reasonably durable, particularly when fitted with harder pinch blades and neck inserts (Table 4-9). 

Generally, the blow mold is a cavity representing the outside of a hlow-molded part. The basic structure of a blow mold consists of a cast or machined block with a cavity, cooling system, venting system, pincholls, flash pockets, and mounting plate. The selection of material for the construction of a blow mold is based on the consideration of such factors as thermal conductivity, durability, cost of the material, the resin being processed, and the desired quality of the finished parts. Commonly used mold materials are beryllium, copper, aluminum, ampcoloy, A-2 steel, and 17-4 and 420 stainless steels. 

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. 

Annealed brass and copper Beryllium copper, phosphor bronze Aluminum sheet Cast irons, aluminum alloys... 

Aluminum, steel, or beryllium-copper is used for the bottle cavity and neck ring. For polyolefin resins, aluminum No. 7075, as well as QC-7, is used. The surface is usually finished with No. 120-grit sandblast, which increases the venting of trapped air. For rigid resins, A-2 tool steel air-hardened to 52-54 HRC is used. The surface finish is highly polished with chromium plating. Cast beryllium-copper is often used for minute detail. As with the parison cavity, water lines are drilled as closely together as possible, perpendicular to the cavity axis. 

With today s CADAM and CNC equipment, the blow-mold industry is producing large blow molds via machining rather than cast almninum (Table 2). However, there are some industries that because of the blow-mold cost and short nm volumes rely solely on cast aluminmn blow molds. They also live with the problem of aluminum pinch-offs, rather than insert steel or beryllium-copper. 

Cores and cavities are often polished and chrome plated to obtain a glossy surface appearance and in some instances to facilitate ejection. Chrome plating is also used vdth corrosive resin molding systems such as polyvinyl chloride. Stainless steel molds have also been used successfully and should not be overlooked. Cast beryllium-copper may be used for production cavities but should be flash-chromed to prevent surface staining with some resin systems, e.g., polycarbonate. 

BRUSH ALLOY 25, a heat-treatable beryllium copper product contains 1.80 to 2.00% beryllium. BRUSH ALLOY 25 is resistant to hydrogen embrittlement, and not susceptible to either sulfide stress cracking or chloride stress cracking. Moreover, in marine and certain industrial environments this alloy outperforms stainless steel, titanium, and most copper based alloys. Beryllium copper is available in a wide range of forms, including strip, tube, rod, bar, extrusions, casting and master alloy, and forging billet. 

The most common heat-treatable copper alloys are the beryllium coppers. They possess a remarkable combination of properties tensile strengths as high as 1400 MPa (200,000 psi), excellent electrical and corrosion properties, and wear resistance when properly lubricated they may be cast, hot worked, or cold worked. High strengths are attained by precipitation-hardening heat treatments (Section 11.9). These alloys are costly because of the beryllium additions, which range between 1.0... 

Castable refractories, ASTM classifications and specifications for, 27 510 Castables, 27 482 Cast alloys, 73 524 Cast copper-beryllium alloys, 3 653t,... 

Impurities above maximum levels indicated in published specifications (42) can affect the properties of the finished casting. Silicon, for example, is normally added to many of the copper—beryllium casting alloys to promote fluidity, but excess silicon reduces ductility. Excessive zinc, tin, phosphorus,... 

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