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Toughest Diamond Bearings You'll Ever Use

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.

Diamond Sintering

The extreme hardness, wear resistance, and thermal conductivity of diamond make it an ideal cutting tool material. However, individual diamond crystals cleave quite easily when struck parallel to certain planes (the process used to facet diamond gemstones takes advantage of these relatively weak planes). As a result, individual diamond crystals do not make good cutting tools—unless they are meticulously oriented.

Diamond sintering overcomes the problem of weak planes in diamond gemstones by bonding a mass of small diamond particles onto a larger, coherent structure. Sintered diamond provides greater toughness and durability than single crystals because the individual crystals in a sintered body are randomly oriented. This prevents cracks from propagating along the weak planes where traditional diamond crystals cleave most easily. Sintered diamonds also provide more uniform wear than a single crystal, while maintaining similar thermal conductivity and hardness properties. All of these factors combine to make sintered diamond the preferred material for cutting rock.

At US Synthetic, the sintering process begins with premium saw-grade diamond crystals. These crystals are sintered together at temperatures of approximately 1400°C and pressures of around 60 kbar in the presence of a liquid metal catalyst. Typically, the diamond is bonded to a tungsten carbide substrate during the same high-temperature, high-pressure process. This sintered diamond and tungsten carbide composite is known in the industry as a polycrystalline diamond cutter (PDC).

Diamond Finishing

The extreme hardness of diamonds presents obvious machining and finishing challenges. In typical machining situations, the finishing tool is harder than the work piece. With diamond inserts, this isn’t possible, since diamond is the hardest known substance. This makes machining diamond analogous to cutting through a wooden beam with a wooden saw. As a result, US Synthetic uses millions of carats of industrial diamond each year to machine and finish PDCs to their final dimensions. Over the years, we have developed specialized techniques and machines for lapping, grinding, polishing, brazing, and cutting PDC inserts. These techniques make it possible for us to finish PDCs to exacting specifications, despite the inherent challenges of machining sintered diamond.

Thrust Bearings

Polycrystalline Diamond (PCD) thrust bearings are comprised of a series of PCD inserts assembled (usually by brazing) in carrier rings. A typical PCD thrust bearing set includes a rotating and stationary bearing ring. These two rings oppose each other with the planar PCD surface of one ring in direct contact with the PCD surface of the mating ring.

During operation, the PCD surfaces of the rotating and stationary rings rub against each other. This rubbing contact exhibits very low friction (typically between 0.05 and 0.07). At higher speeds, the friction in PCD bearings can be further reduced as the bearings transition to mixed lubrication and even hydrodynamic lubrication regimes. Hydrodynamic lubrication occurs when a thin film of fluid separates the opposing bearing surfaces, resulting in very low friction coefficients. Laboratory tests conducted by US Synthetic have measured friction coefficients below 0.01 when hydrodynamic lubrication has been achieved.

The ultra-high hardness and strength of PCD allows US Synthetic Bearings’ thrust bearings to sustain very high loads during operation. In addition, wearing at a very low rate, results in the PCD bearings lasting from 1000 hours to many years, depending on the application. PCD thrust bearings are ideally suited for process-fluid-lubricated applications, particularly those where abrasive particles are present in the fluid. The PCD inserts used by US Synthetic Bearings also utilizes the highest quality steel grade available.

PCD Bearing Capabilities:

  • Specific loads in excess of 22,000 psi (152 MPa)
  • Speeds from 1 rpm to more than 6000 rpm
  • Wear rates less than 0.0004 inches/1000 hours (0.01 mm/1000 hours)
  • Friction coefficients from 0.07 to less than 0.01

US Synthetic Bearings’ thrust bearings are typically custom designed for each application. US Synthetic Bearing’s engineering team can create a specific design for each customers’ application and provide performance estimates. Contact us for more information.

Radial Bearings

Polycrystalline Diamond (PCD) radial bearings are comprised of a series of PCD inserts assembled (usually by brazing) in carrier rings. A typical PCD radial bearing set includes a rotating and stationary bearing ring. These two rings oppose each other with the PCD surface on the inside diameter of one ring in direct contact with the PCD surface on the outside diameter of the mating ring.

US Synthetic Bearings prides itself in its ability to precisely shape polycrystalline diamond. This has allowed Bearings to provide PCD radial bearings that have accurate diameters, tight clearance tolerances, and ultra-fine surface finishes.

During operation, the PCD surfaces of the rotating and stationary rings rub against each other. This rubbing contact exhibits very low friction (typically between 0.01 and 0.05).

The ultra-high hardness and strength of PCD allows USS Bearings’ radial bearings to sustain very high loads during operation. In addition, they wear at a very low rate, resulting in the PCD bearings lasting from 1000 hours to many years, depending on the application. These PCD inserts also utilize the highest quality steel grade available.

PCD radial bearings are ideally suited for process-fluid-lubricated applications, particularly those where abrasive particles are present in the fluid. The PCD surfaces maintain their geometry and exhibit minimal wear in the presence of these abrasive-laden fluids.

US Synthetic Bearings’ radial bearings are custom designed for each application. The Bearings’ engineering team can create a specific design for your application and provide performance estimates for its bearings in that application. Contact us for more information.

Combination Bearing

Some loading scenarios may require bearings that sustain both thrust and radial loads. Polycrystalline Diamond (PCD) bearings can be manufactured by US Synthetic Bearings to meet these requirements. PCD inserts can be assembled in carrier rings and finished with a tapered profile. The taper angle can be adjusted to accommodate higher thrust loads or higher radial loads as required by the application.

In some applications, PCD thrust and radial bearings have been integrated into a single bearing unit to provide for a more compact bearing assembly. In these assemblies, the PCD inserts that sustain the thrust load are assembled into a single carrier ring with the PCD inserts that sustain the radial load rather than the standard configuration where two carrier rings are used – one for each loading direction. Our PCD inserts also utilize the highest quality steel grade available.

USS Bearings prides itself in its ability to precisely shape polycrystalline diamond. This has allowed us to provide PCD bearings for combined loads that have accurate surfaces, tight clearance tolerances and ultra-fine surface finishes.

US Synthetic’s bearings for combined loads are custom designed for each application. The engineering team at USS Bearings can create a specific design for your application and provide performance estimates for our bearings in that application. Contact us for more information.

combination bearing

Wear and Custom Applications

Polycrystalline diamond is an extremely wear resistant material that can be used to protect drilling tool components from abrasive wear caused by contact between the exterior of the tool and the bore-hole wall.

US Synthetic wear parts made of PCD can be used on internal drilling tool components to protect critical surfaces from erosion caused by high-velocity abrasive fluids. In one case, PCD has been used as a replacement for tungsten carbide components that were subjected to accelerated erosion.

Tilting Pad Bearing

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.

Diamond Tilting pad Datasheet (PDF download)

Why Diamond Bearings Underwater?

Hydro kinetic power generator

PCD bearings are ideally suited for operation in process fluids where abrasive particles can cause accelerated wear. Pumping abrasive-laden liquids or mixed phase fluids is a tough job. That’s why, US Synthetic offers the most durable, longest-lasting bearings specifically designed for transfer pumps, Electric Submersible pumps (ESP), stationary pumps, and injection pumps.

Case Study: Diamond Bearing in Renewable Energy  (PDF download)

Pumps and Waste Water Datasheet (PDF download)

Oil and Gas Drilling

Drill String

When there’s simply no room for error or failure, US Synthetic prides itself on offering the longest-lasting diamond bearings and components on the market for down hole drilling tools.

Oil and Gas Drilling Datasheet (PDF download)

Other Applications

US Synthetic uses diamond to solve important problems today, but we also realize that we’ve only begun to explore the possibilities. Because synthetic diamond has many unique properties, that makes it ideal for a wide range of uses both inside and outside the oil and gas exploration industry, and new possibilities and opportunities are continually be explored.

For new ideas or suggestions for using diamond, please contact US Synthetic business development. US Synthetic welcomes the opportunity to put synthetic diamond to work for your business.

The Unique Properties of Diamonds

  • Hardest known material
  • Highest thermal conductivity
  • Highest wear resistance
  • Excellent electrical insulator
  • Extremely low thermal expansion
  • Low coefficient of friction
  • High sonic velocity
  • Optically transparent
  • Wide band-gap semiconductor
  • Chemically inert
  • Biologically compatible