Articles

Using custom hybrid ball bearings that go in rocket-engine controls, and can withstand both cryogenic temperatures and the vacuum of space, is the focus of this article entitled "Bearings Are Rocket Science".

An article discussing self-lubricated PTFE lead NU bearings and acetal-lined pre-lubricated NX bearings, both plated with sintered-bronze substrate on the OD.

This article is about how graphite-metal bearings can handle harsh environments that liquid-lubricated types cannot. A grease-filled ball bearing on an oven-door latch can seize at +550°F as oven temperatures solidify the grease over time. A graphite-based dry lubricant can better tolerate the high temperatures but eventually the bearing balls will skid and damage the race. Graphite-metal bearings can survive temperatures to 1,000°F.

An article discussing how radial play, end play, and contact angle all provide a measure of bearing movement. However, it's not always clear which is the best indicator to typify movement for a specific application. Radial play has been the most commonly used because the other two are usually functions of it.

There are many copper alloys available to be used as bearing materials. Copper lead, copper tin, leaded bronze, aluminum bronze, and beryllium copper are basically the five classes these alloys can be grouped in. Generally, in these alloys, a higher lead content will promote compatibility with soft alloy shafts and can reduce friction in low-lubrication conditions, such as in a start-up. Slightly sacrificed wear resistance is one drawback.

This article shows how to calculate machine reliability based on the life of several bearings. A good way to begin is to define what constitutes failure. Then move on to identifying the most significant modes of failure for the machine. A next step should analyze test data for each failure mode. The article goes on to offer equations to help quantify measurements.

When current passes through them rolling bearings in electric machines can be damaged badly. Craters and fluting in the raceways can cause premature bearing failure under the most severe conditions. Hybrid bearings offer several benefits.

This article deals with car racing and how proper wheel bearing preload can help a race car's performance. Getting the adjustment right can be tricky and will consume valuable time on race day, but not enough preload can cause handling and controllability to suffer. Excessive amounts of preload can rob horsepower and might overheat the bearings, which can lead to early failure.

Cylindrical roller bearings offer high radial capacity, low friction at high speeds, and thrust loads of decent magnitudes. Cylindrical rollers are usually crowned or end relieved resulting in low wear and low sensitivity to misalignment. Precision grade materials like RBEC5 are typically used because cylindricals are almost always used in high speed applications.

Thermally induced seizure (TIS) can completely close running clearance between a compressor sleeve bearing and the mating shaft, causing large commercial air conditioning compressors to lock up after sitting all winter. Opening up running clearances in sleeve bearings can help prevent seizing when oil runs dry.

Cylindrical rollers offer greater radial stiffness and vibration damping than ball bearings. This is because the cylinders can be preloaded, improving accuracy, and is especially true on machine tool spindles and high-speed grinding machines. Grinding wheel life expectancy is extended because the bearings will run truer and the wheel will not have to be dressed as often. Another advantage is that the bearings will run cooler.

A "golf ball like" surface will improve the flow of lubrication inside bearings. A golf ball has dimples because it offers superior aerodynamic characteristics versus one that is smooth. Researchers at SKF have found that dimpled ball and roller bearings produce similar benefits in terms of lubricant flow.

Equipment relying on sleeve or journal bearings can benefit from lower operating temperatures. Cooler running extends oil life, reduces differential thermal expansion of the journal, and causes fewer alignment problems. This article discusses how taking steps to bring down the operating temperature can be necessary and desirable for oilfilm bearings.

Hollow cylindrical roller bearings are designed for light loads, including grinding, machining and milling spindles. By using hollow cylindrical rollers, instead of solid rollers, advantages are provided over standard ball bearings, including reduced vibration, higher operating speeds, low-radial runout, better radial stiffness, and lower operating temperatures.

An article offering basic guidelines to creating the best possible operating environment to prevent bearing failure in electric motors. Rolling element bearings play a pivotal roll in the smooth operation of electric motors. The right bearings for an application allow a motor to run efficiently across its design speed range, minimize friction and power loss, produce less noise, and attain a longer service life.

Journal bearing design involves complex equations for optimizing clearances, viscosity, flow rate, bearing length, minimum film lubricant, and inlet slots. Design equations can be time consuming but, fortunately, are available in chart form. A variety of design problems can be solved with various charts in the literature.

Hydrostatic bearing design is complex because of the greater number of components requiring decisions. The pressure pads in hydrostatic bearings carry the load and most hydrostatic systems use several evenly spaced pads so nonsymmetrical load distributions can be handled. This article shows how to estimate performance by treating pads separately.

Thrust bearings need different cooling designs for each type of thrust bearing. They are similar to sleeve bearings in that the performance of thrust bearings deteriorates with rising operating temperatures. Oil viscosity drops tremendously due to heating in the tight film gaps. This causes the oil film to thin, making it less able to cool the bearing.

Knowing which thrust bearings to use depends on operating conditions and design constraints. Designs range from small flat washers in appliances to large assemblies several feet in diameter. This article goes through the six basic types of thrust bearings and how they should be considered for differing applications.

Journal bearings can operate in harsh environments without any external lubrication. External lubrication systems plague many design engineers by adding design complexity and one more item to be serviced. Added to this is the fact that liquid lubricants are increasingly regulated, creating environmental issues regarding waste grease and oil. But journal bearings made from self-lubricating materials can eliminate secondary lubrication in some cases.