Archive for February, 2015

Rolling Bearings: Parts and Cage Types

Friday, February 27th, 2015

The main parts of the ball bearing are the races and the balls. There is an outer and an inner race. The outer race goes into a bore, and the inner races carries the shaft. In between these two parts is where the balls are placed to create the bearing’s rolling properties.

Likewise, roller bearings follow suit with this placement. In both roller and ball bearings, the rolling element lies between the outer race and inner race. Then, there is a separator between the inner race and the outer race, in which the rolling element actually sits. On the inside of the inner race is where the shaft sits.

Without these basic parts, there is no ball or roller bearing. The image here, from Encyclopedia Britannica Online, shows us how roller and ball bearings are set up within the races.

There are, however, other bearing parts to consider such as flange, shield, and bore. Here you will find a description of these types of parts explained in detail and with a map of terms, from SKF.com.

One additional part, for example, is the bearing cage, or retainer. All rolling bearings contain a cage. Depending on the number of ball or roller sets, the bearing may contain multiple cages. The purpose of the cage is to:

  • Reduce frictional heat in the bearing by separating rolling elements.
  • Evenly space the rolling elements to optimize load distribution.
  • Help avoid damaging sliding movements by guiding the rolling elements while in the unloaded zone.

Cages are stressed by friction, strain, and inertial forces, and can be degraded by high temperatures and certain chemicals. Thus, the design and material of a cage influence the suitability of a rolling bearing for an application. There are different types of cages for different bearing types and operating conditions. Below are three common types of cages.

Stamped Metal Cages: Typically made of sheet steel, stamped metal cages are lighter weight, and provide ample space inside the bearing to help maximize the effects of the lubricant.

Machined Metal Cages: Machined metal cages, typically made of brass or steel, generally permit higher operating speeds.

Polymer Cages: A third type of cage, the polymer cage, which is a fabric reinforced phenolic resin, has characteristics of both strength and elasticity. These cages are able to operate smoothly under poor lubrication conditions.

ABCs of Bearing Terms

Friday, February 20th, 2015

The phrase “you learn something new every day” is true across all industries. Take the time today to review some bearing terminology from A to Z. Whether you work with these nifty devices daily or only occasionally, keeping up to date and expanding your industry knowledge is always time well spent.

Below is a list of some useful bearing terminology from A-Z:

ACCELERATED LIFE TEST:
Any set of test conditions designed to reproduce in a short time the deteriorating effect created under normal service conditions.

BORE:
The inside diameter of the inner ring or cone.

CONE:
The bearing’s inner ring that is fixed to and/or pressed onto a rotating shaft.

DEAD-END HOUSING:
A housing that is not through bored. The machining stops part way through the housing forming a blind hole.

END PLAY:
The amount of axial or end-to-end movement in a shaft due to clearance in the bearings.

FPM:
Feet per minute.

GALLING:
A form of wear in which seizing or tearing of the gear or bearing surface occurs.

HUB GREASE CAP/DUST COVER:
A metal cap that fits over the outer end of the hub to keep grease in and dirt out of the bearing assembly.

INNER RING RACE:
The surfaces on the cup and cone where the rolling elements make contact.

LOAD-CARRYING CAPACITY:
The property of a lubricant that forms a film on the lubricated surface, which resists rupture under given load conditions. It is expressed as the maximum load the lubricated system can support without failure or excessive wear.

MAXIMUM CAPACITY BEARING:
A bearing with filling notches to allow the loading of the maximum number of balls.

NEEDLE ROLLER:
Cylindrical roller with large length to diameter ratio. The length is between three and ten times the diameter, which does not usually exceed 5 mm. The ends of the needle roller may be one of several shapes.

OUTSIDE DIAMETER:
The diameter of the outer ring or cup. It also is known as O.D.

PRELOAD:
Thrust load applied to bearings that support a rotating part

RADIAL LOAD:
A load applied perpendicular to the axis of the shaft.

STRAIGHT MINERAL OIL:
A petroleum oil not containing compounds, animal or vegetable oils or chemical additives.

THRUST:
The continuous pressure of one object against another, parallel to the center of the axis.

UNIPAC BEARING:
A double-row tapered bearing configuration originally designed for light- and heavy-duty automotive applications.

WEAR:
Damage resulting from the removal of materials from surfaces in relative motion.

ZERO CLEARANCE:
No clearance between the roller and races.

*Note this list is not comprehensive. This bearing terms glossary from Timken is very helpful for any bearing terminology you may not be familiar with, or have questions about.

Guide to Timken Greases

Friday, February 13th, 2015

Bearings need lubrication to help reduce friction, transfer heat and protect from corrosion.

The Timken Company, a global leader in bearing and steel technology, also understands the importance of lubrication and friction management. Timken lubricants help bearings and related components operate effectively in demanding industrial operations. They also offer additives for high-temperature, anti-wear and water-resistance, which help to give superior protection in difficult environments. You can turn to Timken for a single source and a variety of lubrication options.

This post will spotlight 7 different Timken grease products, to give you more of an idea about what applications they can help you with.

Timken Premium All Purpose Industrial LC-2 Grease:
Environment – High-wear, moderate loads, moderate speeds, and moderate temperatures.
Application – Agriculture, bushings/ball joints, truck and auto wheel bearings, heavy duty industrial.

Timken Construction and Off-Highway Grease:
Environment – Extreme heat, heavy loads, high sliding wear, dirty environments, slow speeds, shock loading.
Application – Ag/mining, cement plants, construction/off road, rock quarry, earth moving equipment, fleet equipment, heavy industry, pivot pins/splined shafts

Timken Ball Bearing Pillow Block Grease:
Environment – Wet and corrosive conditions, quiet environments, light loads, moderate to high speeds, and moderate temperatures.
Application – Lightly loaded pillow blocks, idler pulleys, oven conveyors, electric motors, fans, and pumps.

Timken Mill Grease:
Environment – Corrosive media, extreme heat, heavy loads, wet conditions, slow to moderate speeds.
Application – Aluminum mills, paper mills, steel mills, offshore rigs, power generation.

Timken Food Safe Grease:
Environment – Incidental food contact, hot/cold temperatures, moderate to high speeds, medium loads.
Application – Food and beverage industries, pharmaceuticals.

Timken Synthetic Industrial LC-1.5 Grease:
Environment – Extreme low/high temperatures, severe loads, corrosive media, slow to moderate speeds.
Application – Wind energy main bearing, pulp and paper machines, general heavy industry, marine applications, centralized grease systems.

Timken Multi-Use Lithium EP1/EP2 Grease:
Environment – Moderate speeds, light to moderate loads, moderate temperatures, moderate water.
Application – General industrial, pins and bushings, track rollers, water pumps, plain and antifriction bearings.

V-Belt Matching – Date, Code, Machine

Friday, February 6th, 2015

For transmitting power, V-belt drives often utilize multiple belts. Belt “matching” is a term used to define V-belts that are of equal length. It is important to have matched belts in these applications to ensure even load distribution.

Should a set of V-belts be operating outside the matched RMA (Rubber Manufacturers Association) tolerance limits, several issues can become problematic – belts will fail prematurely because they are unable to work together; the act of transmitting maximum horsepower will be compromised; the sheave grooves will wear unevenly; and belt whip and vibration will be increased.

Manufacturers do make V-belts within RMA tolerances, but each will be slightly different based on their unique manufacturing processes. Because of this, it is not wise to install a drive with V-belts originating from different manufacturers.

Three common V-belt matching methods:

1. Manufacturing Date Matching

This method is the assumption that you can match V-belts by using a manufacturing date code of the same production time period. There is no assurance that a v-belt made in the same production time frame will have a length within matching limits. This method is therefore not recommended.

2. CODE Matching

The RMA publishes match tolerances based on overall belt length. Some manufacturers offer code matching to designate matched length compliance – like codes mean V-belts fall within the matching limits. Not all manufacturers use code matching and instead fall within standard tolerances.

3. Machine Matching

Although code matching, if possible, is satisfactory for the majority of V-belt applications, some require length variation that falls below RMA matched standards. For these very specific applications, some manufacturers offer machine matching from the factory. This service may come at an additional cost. The manufacturer will offer a secondary physical measurement of each belt prior to shipping to ensure V-belt lengths are identical and meet or exceed RMA standards.

For information on acceptable v-belt length deviations click the link to see our previous post.