Machine Design

Synthetic Sapphire, Ruby For Precision Uses

Synthetic sapphire and ruby materials are becoming the jewels of choice for their extreme abrasive resistance, five times that of carbide.

Their crystal structure and zero porosity permit microfinishes of 2 to be attained. Other features of the materials include extreme hardness, chemical inertness (even to hydrofluoric acid), low-friction coefficient, high thermal conductivity, and excellent wear resistance.

Ruby balls are used in chemical pump-check valves, wind indicators, probe and test-measurement tips, medical check valves, ball-point pens, master ball gauging sets, ball plug gages, sapphire fiber-optic lens systems, tracer tips, gyroscopic wear points, and precision metering-valve assemblies. Sapphire balls can be drilled for use as precision jeweled bearing rollers for low-friction and long-wear applications. The balls' 2,000°C melting point makes them suitable for high-heat applications with no oxidation.

Bird Precision,
One Spruce St., Box 540569,
Waltham, MA 02454,
(800) 454-7369,

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