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Bearing Basics: Just Plane Confusing


Plain Bearings VS. Plane Bearingsplain-plane-bearing

There is some disagreement in the engineering community as to whether a plain bearing is the same as a plane bearing.  Is a plane bearing a flat bearing, or can it refer to bearings with round surfaces, like journal bearings?  This article may not establish a firm answer to this question, but it will give food for thought.

 

The controversy began from the first Bearing Basics post.  Here are other articles on polymer bearings :

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Six Kinds of Polymer Jacket Materials for Spring-Energized Seals


Spring-Energized Seals Jacketing Material

 

polymer-spring-seal-jacket

When selecting a jacketing material for a spring-energized seal, engineers look at the

  • operating temperature,
  • pressure (including whether or not it is static or cyclic),
  • dynamic conditions,
  • media involved,
  • amount of seal squeeze,
  • and the geometry involved

In this article, we are going to look at some of the options out there for a polymer jacketing material.

 

Get even more information on Spring-Energized Seals from the following posts from Advanced EMC Technologies:

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Five Energizers for PTFE Spring-Energized Seals


PTFE Seals

5-energized_PTFE-seals

PTFE spring-energized seals are a popular choice for engineers.  The reasons are many, including their long service life, even wear, and their ability to perform in some of the harshest environments.  They work well in extreme temperatures; can even perform well in situations where operating conditions can vary significantly.  They usually offer a low compression set, have a long shelf life, and work very well in non-lubricated applications.  The use of PTFE results in extremely low friction and excellent chemical compatibility and users can choose from a variety of spring energizers.

ptfe-teflon-spring-energized-sealsAs one of the key components of spring energized PTFE seals, each of these energizers offers a different set of characteristics that allow engineers to find just the type of seal to suit their application’s needs.  In this article, we are going to look at five different categories of energizers, and in what conditions they provide the best service:  coil springs, V springs, helical flat springs, cantilevered finger springs, and elastomeric O-rings.

 

Need more energizing? Check out these informative PTFE Spring Energized Seals articles from the Advanced EMC Technologies blog:

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Polymer Rolling Element Bearings: Deep Groove Ball Bearings


Polymer Roller Bearings

BallBearing-animation -CC licensing
Working principle for a ball bearing 
CC BY-SA 3.0

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:

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What is a Rolling Element Bearing?


Anatomy of a Rolling Element Bearingroller-element-bearing-advanced-emc

A rolling element bearing (which is a type of anti-friction bearing) involves the motion of two surfaces separated either by rollers or balls (the rolling elements) whose primary purpose is to reduce friction.  The typical rolling element bearing will consist of

(a) an inner race,
(b) an outer race (which together form the raceway),
(c) the rolling elements between them, and
(d) usually some type of cage (also known as a separator or retainer) to hold the rolling elements in place and prevent them from contacting each other. 

The only kind of rolling element bearing that does not have a cage is a called a full complement bearing.  The inner and outer race will have a groove in them, in which the rolling elements rest.  

Here are some additional excellent posts on bearings and bushings from Advanced EMC Technologies:

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Polymer Bushings Taking a Beating: Two Important Concepts behind the Wear and Tear


Polymer Bushing Mechanisms of WearPolymer_Bushings_on_Black-Shelf

Bushings have two mechanisms of wear: adhesion and abrasiveAdhesion, as discussed in a previous post, occurs when two surfaces come into direct contact and the atoms from one surface adhere to the other surface.  Abrasion occurs when a harder surface contacts a softer surface and removes material from the softer surface.  For polymer bushings, the primary mode of wear is adhesion.  The key to understanding wear by adhesion is a proper understanding of how polymers respond to friction.

 

Here are some other articles relating to polymer bushings and bearings from Advanced EMC Technologies:

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Bearing Basics: Facts Your Boss Hopes You Know about “Plain Polymer Bearings”


Plain Polymer Bearings

In this article, we are going to look at the different types of “plain” (or “plane”) polymer bearings.  Both spellings are correct, it’s only a matter of blogger preference.   “Plain polymer bearings” is preferred for this article.  Recall that the purpose of bearings in general is to:

  • support shafts,
  • reduce the friction between contacting surfaces,
  • and to constrain motion along one or more axes

There are different ways to classify plain bearings, and in this article we will look at one possible means of classification:  sleeved, flanged, and thrust bearings.   

plastic-bearing-chart

Want even more Bearing Basics? Check out these articles from the Advanced EMC Technologies blog:

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Breakout Torque for Ball Bearings


What Is Breakout Torque?ball-bearings-breakout-torque-Advanced-EMC

Breakout torque (also known as break out torque or break-out torque) refers to the amount of torque required to initiate relative rotation between a rotary shaft and a seal or bearing, and plays a key role in systems that involve oscillatory movement.  Breakout torque is a function of both the inertia of the mechanisms involved and static friction.  In ball bearings, you will often see it referred to as the starting torque, and there it refers specifically to the amount of torque required to start the rotation of one ring of the bearing.

For more articles, infographics, and information check out: 

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PFA and TFM–to PTFE as Excellent Material Choice for Bellows and Diaphragms


Polymer Bellows and Diaphragms

PFA--TFM-Bellows-Diaphragms-Advanced-EMC

PTFE (polytetrafluoroethylene), aka Teflon, is typically the first choice polymer for bellows and diaphragms, but did you know that PTFE isn’t the only polymer you can choose from?  In this article we are going to compare two other polymers – PFA and TFM – to PTFE as a material choice for bellows and diaphragms.

 

 

Need more information? Check out these Advanced EMC Technology posts.

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