Antifriction bearings ppt

1. GOVERMENT POLYTECHNIC HOSADURGA
MECHANICAL ENGINEERING
2021-2022
PRODUCT DESIGN AND DEVLOPMENT
1.RANGASWAMY S
2.SHAMITH S M
3.SHARATH P
4.SYED SIDDIQ
5.SYED SADATH
6.TEJAS H N
7.THIPPESH D
8.THIPPESH D B
PRESENTATION ON ANTIFRICTION BEARINGS
GUIDED BY: SWAMY S R SIR
PRESENTED BY :

2. What is a Antifriction bearing?
• An antifriction bearing is a bearing that contains moving elements to
provide a low friction support surface for rotating or sliding surfaces.
Antifriction bearings are commonly made with hardened rolling elements
(balls and rollers) and races.

3. Bearing Functions
• All bearings have three main functions:
• • Reduce Friction
• • Carry Load
• • Guide Parts
•
• Friction
• Friction is the resistance to movement between two or more
bodies. Friction has several forms, but the most relevant
• concerning bearings are static, sliding and rolling friction. Note that
sliding and rolling friction are also sometimes referred
• to as dynamic forms of friction.

4. • Static Friction Holding a Box Stationary
•
• Rolling friction – friction between two bodies when one
rolls across another. For example, when an car wheel rolls
across a
• road. Rolling friction is usually less than sliding friction.

5. • Rolling Friction (roller slides left to right)
• Loads
• Bearings are expected to carry loads during their working life.
Loads may be axial, radial or combined. Bearings must
beselected based upon the loads and service conditions they
are likely to encounter. Incorrect sizing and selection of a
bearing may lead to bearing failure.

6. • Bearing Loads
• Axial loads – loads which are applied parallel to the shaft;
sometimes called thrust loads.
• Radial loads – loads which are applied perpendicular (90 degrees)
to the shaft.
• Combination loads – loads which are a combination of both axial
and radial loads; sometimes referred to as angular loads.

7. Anti-Friction Bearing Components
• The subject of anti-friction bearings is made more difficult due to the
varying terminology that is used to describe identical
• parts. The below table lists bearing components along with additional
common colloquial names.

8. Anti-Friction Bearing Types
• Journalball Bearing
• Cylindrical Bearing
• Needle Bearing
• Foot step Bearing
• Plumber Bearing

9. Journalball Bearing
• Journal or sleeve bearings make use of a pressure wedge of fluid
that forms between the rotating shaft and the bearing. The portion
of the shaft supported by the bearing is called the journal and is
usually hardened for wear-resistance. Bearing pad material is
usually a softer material such as tin- and lead-
based babbitt, bronze, copper-lead, sintered powdered metal,
carbon, PTFE, etc.
• As the shaft rotates in the bearing clearance it tends to want to
climb up the bearing wall, creating a region of high pressure in the
oil film which supports the shaft journal. As the load on the shaft
varies, so too does this region of high-pressure, making journal
bearings quite tolerant of overloads and shock loads.

10. • A journal bearing that has developed this full hydrodynamic lubrication
could run forever as there is no wear. Wear occurs upon start-up, however,
since there is no supportive oil film when the shaft is at rest. Thus, soft
materials are preferred for bearing liners, particularly materials with low
frictional coefficients. Some designs rely on an auxiliary pump that
pressurizes the bearing until the shaft can begin producing the
hydrodynamic wedge.

11. *Cylindrical Bearing
• One of the major series of bearings that have the capability to withstand heavy
radial loads is cylindrical roller bearings. Just as the other bearings are named after
their Rolling elements, the same applies here too. The rolling elements of the
bearing are in the shape of “Cylindrical Rollers”.
• The following points can be noticed in the constructional aspects of the cylindrical
roller ball bearing:
• The rollers of the cylindrical roller bearings along with the cage are guided inside
the integral flanges of the outer race.
• · The inner ring is normally a separate entity and be assembled separately in the
assembly. This helps the bearing to be mounted in conditions where both the outer
and inner races are subject to interference fits.
• · The inner ring is normally chamfered at its outer diameter in order to facilitate the
free entry of inner race into the roller elements mounted along with the cage.
• Certain other features in the construction are available which become the variants
for the cylindrical roller Bearings.

12. * Variants of Cylindrical Roller Bearings:
Before be proceed on the variants we must surely have a look at the various
variants diagrammatically.

13. NU Type: As seen in the photo, this type of cylindrical roller bearing does not posses any collar on its inner
race, the rolling elements are mounted in the flanged Outer race. This type of bearing has the capability to
carry only radial loads and cannot carry any axial load on it.
N Type: This variety is just the same as the NU type except for the change that the rolling elements are
mounted onto the inner race along with the cage. This type can only carry pure radial loads and cannot
withstand any axial load.
NJ Type: This variety of bearing tends to posses a collar on its inner race at one end. This collar is normally
positioned in such a way that it transfers the axial load in the shaft to the rolling elements. This is the type of
cylindrical roller bearing which is capable of carrying axial load to a certain extent. The extent of the axial load
that can be carried by the bearing is dependent only on the specific bearing.
NUP Type: This type of bearing possesses an integral collar in the inner race and a loose collar mounted to the
inner race. This enables the bearing to locate the shaft axially in both directions.
Technical Specifications:
· The cylindrical roller bearings are normally indicated by their type on the First i.e. NU,N, NJ or NUP on the first
and is then followed by the series number. For Example: NU 210 denotes a NU type bearing having a number
210.
· The bearing is available in different cage materials like polyamide cage, machined brass cage and pressed steel cage

14. *Needle Bearing
• Needle roller bearings have a small cross-sectional height therefore
contribute to keeping the overall machine lightweight and compact. As
such, they are used across a broad scope, including cars, motorcycles,
electric machinery, machine tools, aerospace devices, office equipment
and other industrial machinery.
• Transmission
• The automatic transmission system of a vehicle uses needle bearings as
well as several other types of bearings. These bearings are usually
collected within a round cylinder held together by assembly grease. Since
the bearings are not fastened to the cylinder, they can fall easily from the
carrier if not handled with care. The main purpose of the needle bearings
contained within the transmission system is to reduce friction and control
shaft endplay.

15. Benefits of Needle Bearings in Vehicles
• Now let's take a look at some of the reasons why needle bearings are
the preferred choice of bearings in automobiles:
• Needle bearings have greater load carrying capability with respect to ball bearings,
since surface contact is across a line for needle bearings, as compared to a point
for ball bearings.
• With the help of needle bearings, friction is decreased significantly and torque is
transmitted with great efficiency while dealing with static loads and oscillating
surfaces.
• Valve stem wear is also reduced with the help of needle bearings, since the load
on the bearings is spread over a larger surface for increased durability.

16. * There is also less added clearance in needle bearings, which means the
difference between the diameter of the shaft and the diameter of the bearing
is greatly reduced, making needle bearings far more compact than ball
bearings.
* Thus we see that needle bearings play a very important role in the
automobile industry, and are responsible for keeping the internal components
of the vehicles running smoothly with the least amount of friction.
Needle Bearing

17. • A footstep bearing is a cylindrical rigid block with a solid
foundation. It has a cavity inside it within which the shaft is
placed. The footstep bearing supports a vertical shaft.
• Many a time vertical shafts overhang, thus the footstep
bearing is used as end support.
• Long shafts in machines, when in use tend to bend due to
their own weight and thus cause vibration, noise, and
inefficient power delivery.
• A Footstep bearing enables free rotation of the shaft inside it,
also while supporting it with minimum resistance.
*Foot step Bearing

18. Construction of Foot step bearing
• The footstep bearing is made up of the following components:
• The body
• Disc
• Pin
• Bush
• The body
• The base also known as the body is made up of Grey cast iron, spheroidal
cast iron, or cast steel and is bolted to a foundation or a rigid structure.

19. Body of foot step bearing
The body has a cylindrical extrusion inside which a small hole for the pin to
fit is provided as shown in the figure below. There is a small cut-out at the
top part of the cylinder for locking the snug of the bush.
Disc
The disc is a circular part with its top surface being concave. The disc
is placed at the bottom of the cylinder of the body, such that the hole
of the disc and the body align perfectly

20. Disc of footstep bearing
* The main function of the disc is to support the face of the shaft and prevent
the wear of the body due to the rotating of the shaft.
* The disc is made up of softer material like gunmetal. The disc gets worn out
due to the rubbing action and is easily replaceable.
Pin
The pin is made up of Fe 410W. The function of the pin is to secure the disc to
the body and prevent the disc from rotating due to the rotation of the shaft.

21. • Half part of the pin is in the body whereas the other half is inside the
disc.
• Bush
• The bush is a hollow cylindrical part inside which the shaft is placed. The
bush is placed inside the cylindrical part of the body.

22. Bush of Footstep bearing
The bush is made up of gunmetal or other soft material and serves the
same purpose as the disc. The main function of the bush is to protect
the body from wear caused due to the rotation of the shaft inside it.
The bush has an extruded part at the side called the snug. The sung fits
in the cut-out of the body. This prevents the bush from rotating when
the shaft rotates inside it.

23. Assembly of the Foot step bearing
•The assembly of the foot step bearing starts with the body. The body is
placed and fixed to a strong foundation with the help of the slots provided on
the base of the body.
•The pin is then taken and placed into the hole provided into the body.
•The disc is then taken and then placed over the such that the top part of the
pin is in the disc.
•Now, the bush is taken and fitted inside the cylindrical body such that the
snug fits in its place.
•The assembly is ready, then the shaft is placed inside the bearing.
The same process is repeated vice versa to dismantle the Foot step bearing.

24. Limitations of foot step bearing
• Unlike the pedestal bearing or the plummer block, the foot
step bearing can be placed at the bottom of the shaft only.
• The foot step bearing cannot be efficiently lubricated.
• Also the bush and disc have to be replaced from time to time
due to we

25. *Plumber Bearing
• A plumber bearing (or plummer block) is a pedestal used to
provide support for a rotating shaft with the help of
compatible bearings and various accessories. The assembly consists
of a mounting block which houses a bearing.[1] The block is
mounted to a foundation and a shaft is inserted allowing the inner
part of the bearing / shaft to rotate.[1] The inside of the bearing is
typically 0.001 inches (0.025 mm) larger than the shaft to ensure a
tight fit.[2] Set screws, locking collars, or set collars are commonly
used to secure the shaft.[2] Housing material for a pillow block is
typically made of cast iron[1] or cast steel.

26. • A pillow block usually refers to a housing with an included anti-friction
bearing, wherein the mounted shaft is in a parallel plane to the mounting
surface, and perpendicular to the center line of the mounting holes, as
contrasted with various types of flange blocks or flange units. A pillow
block may contain a bearing with one of several types of rolling elements,
including ball, cylindrical roller, spherical roller, tapered roller, or metallic
or synthetic bushing.[1] The type of rolling element defines the type of
pillow block. These differ from "plummer blocks" which are bearing
housings supplied without any bearings and are usually meant for higher
load ratings and a separately installed bearing.[1] Plummer block bearings
are designed for more corrosive environments.[1]

27. • The fundamental application of both types is the same, which is to mount a bearing
safely enabling its outer ring to be stationary while allowing rotation of the inner ring.
The housing is bolted to a foundation through the holes in the base. Bearing housings
may be either split type or solid type.[1] Split type housings are usually two-piece
housings where the cap and base may be detached,[1] while solid are single-piece
housings.[1] Various sealing arrangements may be provided to prevent dust and other
contaminants from entering the housing. Thus the housing provides a clean
environment for the environmentally sensitive bearing to rotate free from
contaminants while also retaining lubrication, either oil or grease, hence increasing its
performance and duty cycle.
• Bearing housings are usually made of grey cast iron.[1] However, various grades of
metals can be used to manufacture the same, including ductile iron, steel, stainless
steel, and various types of thermoplastics and polyethylene-based plastics. The bearing
element may be manufactured from 52100 chromium steel alloy (the most common),
stainless steel, plastic, or bushing materials such as SAE660 cast bronze, or SAE841 oil
impregnated sintered bronze, or synthetic materials.
• ISO 113 specifies internationally accepted dimensions for plummer blocks.[3
•