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Polymer Roller Bearings

BallBearing-animation -CC licensing
Working principle for a ball bearing 
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Radial Deep Groove Ball Bearings (also known as Conrad bearings) are some of the most commonly used ball bearings.  In deep groove ball bearings, the dimensions of the raceways are almost the same as the dimensions of the balls.  The grooves consist of circular arcs with a radius just a little bit larger than the ball radius.  The groove depth is typically ¼ of the ball diameter.  This geometry of the bearing to carry radial, axial, and combined loads.  However, they are used when the primary load is going to be radial.  Its ability to carry an axial load depends on how much clearance there is in the bearing after installation: if the balls are able to contact the groove at an angle, then they can support a radial load.

plastic-bearing-double-rowYou can find them with either single or double rows. Double rows work well supporting moment loads that may be acting on the shaft. These bearings are usually not separable, and the raceway is continuous.  They are also not self-aligning, so it is important that they be correctly aligned when they are installed.  Also note that even if they are not going to be lubricated, deep groove bearings are going to need some type of seal or shield to protect them from contaminants that will compromise both their performance and life span.

 

More information on polymer bearings from Advanced EMC Technologies:


Raceway and Cage Materials

Polymer radial deep groove ball bearings usually consist of a polymer raceway and cage with balls that are either stainless steel, glass, or plastic. Raceways and cages may be made from a variety of polymers, including POM (Polyoxymethylene), PA (Polyamide), PE (Polyethylene), PP (Polypropylene), PEEK (Polyethertherketone), or PP (Polypropylene).

deep-groove-polymer-bearing-diagram
Radial-deep-groove-ball-bearing din625-t1 2rs 120” 

Ball Materials

Steel balls have pretty good chemical resistance, but weight more and thus have more inertia.  Glass balls are usually chosen when the engineer is trying to completely avoid the use of metal; they weigh less than the steel balls and have excellent chemical compatibility.  Polymer balls weigh less, can have excellent chemical resistance, and are the quietest running of the three options.

Applications

They work well for high speed applications, and are known for low torque and low noise operation.  They are also preferred when one of the design goals it to reduce power loss.

There are many industries that can benefit from these bearings.  These include the chemical, food, pharmaceutical, medical, and photography industries.  They are also used in office products, vacuum applications, and prototyping.

Benefits

Deep-groove radial ball bearings offer low noise and low torque.  They can be used in high speed applications.  Due to their design, they can be manufactured to achieve excellent rotational accuracy.  They can also tolerate a small amount of misalignment.  Note that if subject to impact loadings they can be seriously damaged.

 

For more information get your free copy of Advanced EMC Technologies, ” 7 Step Process in Bearing Selection.”

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