Balls and sphere shapes are used in applications requiring a spherical product (eg., valves, bearings). They are fabricated from materials such as carbides, ceramics, sapphire, metals, plastics, rubber, and elastomers. To select the proper material for balls and sphere shapes the end-use applications must first be considered.
Carbides and carbide materials for balls and sphere shapes include silicon carbide, tungsten carbide, titanium carbide and other compounds of a metal (Ti, W, Cr, Zr). Another option is the combination of metalloid (B, Si) and carbon. Because of their excellent wear resistance and high hardness, carbide balls are used in products such as bearings, ball screws, valves, flowmeters, gages, gaging tracers, and ballizing balls. These balls and sphere shapes are also used in other wear applications.
Ceramic materials for balls and sphere shapes consist of inorganic non-metal compounds that include oxygen, carbon, or nitrogen. Examples include aluminum oxide, silicon carbide, silicon nitride, and zirconium oxide ceramics. These materials have high melting points, excellent wear resistance, and provide oxidation and corrosion resistance. Ceramic balls and sphere shapes are used in bearings, check valves, flowmeters, and gaging devices. The brittle nature and lower thermal shock resistance of certain ceramics can be a drawback in some applications.
Silicate-based glass materials for balls and sphere shapes have an irregular, liquid-like (non-crystalline) molecular structure. Heating these materials at an adequate temperature produces a fused melt. Glass balls maintain exceptional corrosion resistance and dimensional stability that can tolerate temperatures up to 600° F. Glass balls and sphere shapes are suitable for check valves, rotometers, flowmeter aircraft instrumentation, and process equipment applications.
Metals and alloys can be heat-treated or tempered to produce balls and sphere shapes. Ferrous metals and alloys for balls and sphere shapes include carbon steels, alloy steels, stainless steels, cast iron, cast steel, maraging steel, and specialty or proprietary iron-based alloys. Steel and stainless steel balls are often used in bearing and check valve applications. Nonferrous metals and alloys include: alloys of aluminum, copper, and/or nickel, including proprietary metals such as Inconel® (Special Metals, Inc.) and Hastelloy®(Haynes International); nickel-copper alloys such as Monel® (Inco Alloys International, Inc.); cobalt (stellite or cast cobalt); precious metals; and refractory or reactive metals.
Balls and sphere shapes that are ground from Inconel® and Stellite® (Deloro-Stellite Corp.) are useful in applications where high corrosion and heat resistance is required; such as, demanding chemical, paper, textile, food, and pharmaceutical applications that require non-ferrous balls and spheres. Hollow aluminum and stainless steel balls and sphere shapes are used for float applications in chemical fluid systems. They are also used to reduce component weight in aircraft valve applications and as anodes in plating processes.
Plastic, rubber, and elastomer balls and sphere shapes are made of organic, synthetic, or processed polymers that are supplied as raw materials or stock shapes. They typically consist of thermoplastic or thermosetting resins that are easily shaped. While most plastics and elastomers are corrosion resistant, they are softer and limited in heat resistance compared to metals, ceramics, glasses, or carbides. Plastics and elastomers maintain good electrical insulation and self-lubricating properties depending on fillers and chemistry. Plastic balls and sphere shapes are useful in light load-bearing, check valve, flow control, and flowmeter applications. Rubber balls and sphere shapes are highly resilient and flexible. They are useful in screen deblinding, cabinetry (eliminating chatter or vibration), mounting, and check valve (quiet or low-noise sealing) applications.
Sapphire balls and sphere shapes are a highly pure, dense, single-crystalline form of aluminum oxide, which may contain chromia, titania, yttria, or other dopants. Sapphire has high hardness, a low coefficient of thermal expansion, and can withstand temperatures up to 3250° F. Sapphire is usually transparent or translucent, and highly resistant to corrosion and abrasion. Sapphire ceramic balls and sphere shapes are used in bearings, check valves, flowmeters, and gaging devices. The brittle nature and lower thermal shock resistance of sapphire can be a drawback in some applications.
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