HobbyParts Speed - Bearings - Technical Information

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HobbyParts Speed - Bearings - Technical Information

Bearing Speed / Limiting Speed

Limiting speed is the speed at which a bearing can operate at light loads and normal operating conditions without failing prematurely. It is a guide only. Application speeds can vary greatly.

Bearings in dental handpieces often run at speeds of up to 3 times their limiting speed, however they are not expected to last as long as bearings in less demanding applications.

Published limiting speeds apply to applications involving a rotating shaft. Speeds for applications involving a rotating housing can be up 30% lower.

Many factors combine to affect the attainable speed and expected life of a bearing. Factors affecting speed and life include ...

load
vibration
lubrication
cage type
operating temperature and internal clearance
moisture / contaminants
mounting
precision
closures

Limiting speeds can be found on our Minifind CD which can be ordered by our resellers.

Load

The limiting speed of a bearing is based on lightly loaded running conditions. Increasing the load will adversely affect the attainable speed and/or bearing life. An increase in either load or speed may sometimes be compensated by a decrease in the other resulting in a similar life expectancy.

It is important to note that a deep groove radial ball bearing should not be subjected to undue axial loads, and axial type bearings (such as angular contact or thrust bearings) should not be subjected to undue radial loads.

Vibration

Vibration is a major cause of bearing failure by causing brinelling or flaking of the races. If your bearings are operating under vibratory conditions you will not be able to achieve the same speeds that you could under perfectly smooth conditions. Attempting to increase speeds under vibratory conditions will quickly lead to bearing failure.

Lubrication

Lubrication is a major consideration with regards to bearing speed. We list a limiting speed for both standard oil and standard grease lubrication in the datasheets on our Minifind CD

Oil lubrication generally achieves higher speeds than grease lubrication. Increasing lubricant viscosity will reduce the permissible speed, whilst decreasing the viscosity will increase the permissible speed. Oil mists are used for very high speed applications. Use of silicone based oils and greases requires lower speed.

Cage Type

Often, the first part of a bearing to fail under high speed is the cage. The use of a synthetic cage designed for high speed helps to correct this. Synthetic cages are made from a variety of material including nylon, polyamide and phenolic. The datasheets on our Minifind CD show the limiting speed allowing for each bearings cage type.

Temperature and Clearance

Low or high temperatures can adversely affect bearing life. Low temperatures can cause components to become brittle and lubricants to harden. High temperatures can cause parts to bind due to expansion and lubricants to melt and evacuate the bearing. These effects can be somewhat controlled by use of an adequate high or low temperature lubricant and purchasing bearings with increased internal clearance to allow for expansion.

Moisture and Contaminants

Strict cleanliness is essential to the correct functioning of bearings. Bearings requiring contact with excessive moisture or even lubrication by water should be made from 316 stainless steel, acetal or even full ceramic. These materials are only suitable for low speeds and loads.

Mounting

Correct mounting is essential to the correct running of the bearing. A poorly aligned assembly, or incorrect housing/shaft tolerances will result in slower attainable speeds and premature failure. Incorrect housing/shaft tolerances can result in a lessening of the bearing internal clearance

Precision

The use of higher precision may be suggested if the bearing is to run at speeds above the standard limiting speed. MBA limiting speeds are already adjusted to take consideration of this effect.

Closures

Contact seals reduce the speed capabilities of a bearing. MBA limiting speeds are already adjusted to take consideration of this effect.

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Tables and information on this web site should be read as a general guide only. The relevant standards should be consulted to ensure accuracy

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Site Summary:

H.E. Supplies (Hobby Engineering Supplies) offers thousands of products including remote controlled cars, planes, boats, and helicopters. We stock spare parts for remote controlled models. Our range includes the popular Solarbotics solar model kits and spares. We also distribute the full range of miniature engineering products from Miniature Bearings Australia. This range includes small bearings, timing pulleys, timing belts, seals, o-rings, gears and more. Also available from our store in Mansfield Queensland are a full range of lubricants, adhesives, kites, balsa wood and plastic rod and sheet materials. See our Online Catalogue for more information. Our main business is handled from our sales counter and showroom at 186 Wecker Road Mansfield, Queensland, Australia, but we also sell by phone, fax, online and mail order. We offer all of our hobby parts through our online store and some of the more popular MBA items. If you would like to purchase other MBA items online, Small Parts and Bearings offer the full range in their online catalogue.

Using the links at the top of this page you will find extensive information including catalogues (Products and Store link), technical data, and other product specific information.

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