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Custom Bearings

All US Synthetic PCD bearings and wear parts are custom designed for each application. We work closely with our customers to develop bearings that can be easily integrated into existing or new tools. The US Synthetic Bearings engineering teams provide design support, prototype manufacturing, and in-house laboratory testing to help our customers meet the needs of their specific applications.

Custom Applications

Diamond as a Bearing Material

Polycrystalline diamond is known for its high thermal conductivity, low coefficient of friction, high toughness and other preferred physical and mechanical properties. Having a bearing material with high thermal conductivity reduces localized temperature extremes that lead to bearing degradation. During starting and stopping, a high thermal conductivity will reduce the likelihood of causing localized welding of the surfaces, which in turn leads to scoring and galling of the bearing surface. In sliding bearings, low coefficients of friction are desired in order to decrease heat generation and reduce power loses. A bearing material exhibiting a large fracture toughness will decrease the likelihood of race damage during extreme operation conditions. Because of its extreme hardness, polycrystalline diamond is very resistant to wear from abrasive particles in lubricants or process fluids.

Physical and Mechanical Properties of Bearing Materials


Properties Polycrystalline Diamond (PCD) Tungsten Carbide Steel (4140) Silicon Nitride Silicon Carbide
 
Coefficient of Friction 0.05-0.08** 0.2-0.25† 0.42‡ -- --
Thermal Conductivity (W/m*K) 543 70 42.6 30 85
Fracture Toughness (MPa√m) 13-15 10-25 50 4 3.5-4
Hardness (GPa, Knoop) 49.8 1.8 0.2 1.8 2.4
Compressive Strength (GPa) 6.9-7.6 2.68 -- -- 2.5
Young’s Modulus (GPa) 841 669-696 205 296 434
Tensile Strength (MPa) 1,300-1,600 334 415 520 500

*ASI 4140 Steel, annealed at 815°C (1500°F) furnace cooled 11°C (20°F)/hour to 665°C (1230°F), air cooled, 25 mm (1 in.) roun(1100°F) temper)
** PCD on PCD in H2O, dynamic, dynamic
†Tungsten Carbide on Tungsten Carbide, static
‡Steel (Hard) on Steel (Hard), dynamic
YAt 100˚C
Sources: Bertagnolli, US Synthetic; Roberts et al., De Beers; Cooley, US Synthetic; Jiang Qian, US Synthetic; Glowka, SNL; Sexton, US Synthetic; Lin, UC Berkeley, MatWeb.com, Cerco

Coefficient of Friction

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Thermal Conductivity

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Hardness

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Fracture Toughness

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