Monday, July 27, 2020

Rolling contact bearing part 2

Rolling contact bearing

Learning Objective of this chapter
  • Explained the different combination of bearing
  • Decrease the internal clearance and pre-load of bearing
  • Learn about bearing codes

Interview question on bearing

Combination of bearing use in equipment

Three type of combination of bearing mentioned below
  • O type of arrangement (DB) back to back
  • X type of arrangement (DF) face to face
  • Tendon arrangement

O type of arrangement (Back to Back)

The distance or (pressure point) between inner and outer cage is more because the smaller deformation occur due to moment loads this type of arrangement bearing can take large moment load than X type of arrangement.
Two angular contact ball bearing or two taper rollers bearing which take combine loads and can be paired in combination of X arrangement, O arrangement and tendon arrangements. O arrangement two bearing use for directional and axial load

X type of arrangement (Face to Face)

X type of arrangement use if the shaft going hot during the operation, to prevent bearing damaged from this pre-load given during mounting of bearing on shaft increases.
But in O type of arrangement the co-efficient of thermal expansion for bearing and other part will be same. Because the axial and radial thermal expansions cancel out each other, and in this condition given pre-load during installation does not change.

X type of arrangement bearing can tolerate the inaccuracy of housing and it can tolerate shaft deflection due to poor shaft rigidity.
Tandem arrangement use for heavy loads with low speeds.

What is cage bearing and full complement bearing?

full complement bearing

Full complement without cage bearing have a greater number of rolling elements. It can support very large loads. But mutual contact of rolling elements increases friction to each other. It is run at relatively low speed or to slewing motions.

Caged bearing

Caged bearing has smaller number of rolling elements. It can support less loads as compared to full complement bearing. But in caged bearing mutual contact of rolling elements have less friction to each other, rolling element are separate in it. It can run high at speeds.

Where full complement bearing are used?

High load with very low speed.

Types of Bearing internal clearance

Zero operational clearance and slight pre-load, some positive clearance, arrangement has some pre-load.

What happen if clearance is less than required in a spherical roller bearing after mounting on the shaft?

Bearing life reduced and creating noise during operation due to thermal expansion. What do you mean of bearing pre-load.

why it is important?
  • Enhance the bearing stiffness
  • Enhance the accuracy of shaft guidance
  • Compensate for wear and settling in operation
  • Give a long service life

Radial load


Cylindrical roller Double row angular contact Deep grove

List of Axial load bear bearing

Single row angular contact,  Taper roller bearing,  Deep groove.

Rolling contact bearing materials is that silicon Nitrite, 52100 steel, 440c stainless steel, m 50 steel.

Question

Most of ball bearing are made of ?

A) 20MC5, B) SAE2100, C) Silicon Nitrite, D) 440c stainless steel.

axial and radial force

Code for bearing

Bearing code are combination of three term (letter and number), that is prefix, basic code, suffix.
Prefix
There are 4 different prefixes use in bearing nomenclature,
R means ring of cylindrical or taper roller bearing with rolling element and cage but not separable ring.
WS means ring and ball of thrust ball bearing.
GS means housing washer of thrust ball bearing.
K means cage with rolling elements. Go for code of bearings.




Suffix
E high capacity bearing,
UA, UO AND UL means universal design of single row angular contact ball bearing with closed axial preload, no clearance and light preload respectively.
ZR and 2ZR bearing with one or two shields.
RSR and 2RSR bearing with one or two shields,
J, Y, M, F, L, T and TV pressed steel, pressed brass, machined brass, machined light alloy and plastic cage.
K means bearing with taper bore, taper 1:12 ratio.
PN (PO), P6, P5, P4, P2 tolerance class.
C1, C2, CN(CN), C3, C4, C5 bearing clearance.

For know, about inside bore, multiply last two digit with 5, and if D = 10, 12, 15, 17 then code number will be 00, 01, 02, 03 respectively.
And if d is more then 480 mm then written directly on bearings.

Full bearing code description with example 22320K EJ W 33 C33 C3 Means spherical roller bearing, straight bore, clearance is more then normal clearance, bore diameter is 120 mm, machined brass cage, high capacity bearing.

Sunday, July 19, 2020

Interview question on bearing

Interview question on bearing

What is bearing and why is it used?

Bearing is machine element, it is use for reduce the friction between two part of the machine, it is also increase the reliability and availability of a machine, and use for increase the life of machine and reduce the down time. There are many factors considered during the selection of appropriate bearing for a machine.

What factors are considered during selection of the machine?

there are many factors needed to be considered during the selection of a bearing are that is mentioned below. Equipment speed, equipment operating load, shaft torque, temperature of services fluid, availability of lubrication system, viscosity of the services fluid, type of load to be act on the machine and others.

What is function of bearing?

The main function of bearing are reducing the friction, support the machine shaft, smooth operation, increase reliability and availability of the machine parts.

How many type of bearing?

Three are many types of bearing but mainly two types of bearing mentioned below.
  • Rolling element bearing

    1. Ball bearing

      1. Deep groove ball bearing
      2. Angular contact ball bearing
      3. Self-align ball bearing
    2. Roller bearing

      1. Taper roller bearing
      2. Cylindrical roller bearing
      3. Needle roller bearing
      4. Spherical roller bearing
  • Plane bearing

    1. Sleeve bearing
    2. Thrust bearing
    3. Flange bearing
    4. Mounted bearing
    5. Spherical bearing
types of bearing


For father classification follow the link basics of bearing

How to calculate bearing life?

The bearing life calculation is based on operating load, operating speed and operating hours. According to ISO 281 the basic bearing rating calculation formula mentioned below, whereas c= basic bearing dynamic rating, p= exponent for bearing life, 3 for ball bearing and, 10/3 for roller bearing, P= dynamic bearing load, L10= basic bearing life (at 90% reliability) millionth of revolution.

bearing life calculation

What is L 10 bearing life?

L 10 means basic bearing life (at required % load reliability) millionth of rotation.

Where are bearings use?

The bearings are used in (small, medium, and heavy) machinery like pump, compressor, turbine, automobile, electrical motor, agriculture machinery, stitching machine, and all types of rotating machinery.

What is the application of bearing?

There are many applications of bearing according to their function. These are mentioned below.
  • Agriculture machine
  • Automobile (heavy and light)
  • Aeroplane
  • Plant machinery like, pump, compressor, turbine, blower and other type of rotating equipment.
  • Power generation equipment and others.

How to select bearing?

For bearing selection there are many factors need to considered
  • Rpm of the equipment
  • Carrying load of the machine shaft
  • Difficulty of installation of bearing
  • Space required for installation
  • Angular and parallel misalignment tolerance
  • Rigidity of the shaft and bearing both
  • Torque generates during operation
  • Lubrication availability
  • Easy to installation and dismantle
  • Thrust generate during operating
  • Viscosity of the fluid

Which alloy metals used to make bearing?

There are many types of alloy used for make bearing like, bronze, aluminium, zinc, lid, tin, antimony and other types of white alloy. These types of alloy are also used for heavy load and high-speed application.

Which type of bearing is used for heavy load and high-speed application?

Ball bearings are used for high speed application and minor misalignment tolerance, due to its point contact configuration. But for more load or heavy-duty application use for roller bearing. During the selection of bearing mainly 3 factors needed to consider temperature, speed and load.

What is radial play in bearing?

The radial play means, balls clearance within the bearing both cages, it is indicated by C1 to C5. Where C1 is tightened and C5 is looser than C2 > C3 > C4 > C5.

How to select lubricant for bearing?

There are three factors that must be considered during selection of bearing that is temperature, speed, and loads carried by the shaft.

What type of bearing use in overhang centrifugal pump?

Mostly angular contact ball bearing and deep groove ball bearing are use in overhang centrifugal pump.

Wednesday, July 15, 2020

Basics of bearing

Bearing

The term bearing comes from the bear, a bearing is a component that supports load while permitting relative motion between two parts of the machine. Bearing is an important part of a machine which carries load, reduces friction and gives a smooth operation. The selection of bearings is based on the requirement of the operating load for a given period of equipment. Centrifugal pump


Type of bearing

  •         Rolling contact bearing
  •         Plane bearing (sleeve bearing)
                      
type-of-bearing

Type of bearing


Rolling element bearing


A rolling element bearing carries load between two parts by placing the circular element between the inner and outer race of the bearing. Rolling contact bearings are designed to carry a high radial and high axial load, or combination of both. Many types of circular element are used in rolling element bearings like, balls, spherical roller, needle roller, taper roller, circular bearing. Rolling contact bearings are divided into two categories.


Types of rolling contact bearing

  • Ball bearing
  • Roller bearing
But these two types of bearing are divided in many parts,  latter we will discuss in detail. There are a variety of Rolling contact bearings available in the industry.


Types of ball bearing

Ball bearings are classified into three types
  • Deep groove ball bearing
  • Angular contact ball bearing
  • Self aligning ball bearing
To get deep knowledge of any type of bearing, you have to learn about construction, application, and features.


Deep groove ball bearing

Deep groove ball bearing run with very low friction because of the point contact between balls, inner race and outer race. It has less noise due to being preloaded during installation. Very little misalignment is tolerated between the inner and outer races of bearing. Axial movement is not permitted, this type of bearing can not be used as a floating type.
Deep groove ball bearing

Deep groove ball bearing

Applications


  • Motorcycles and other types of low weight vehicles
  • Small and medium duty electric motor, and electric fans.
  • Convener systems and small size or light duty gear boxes.
  • Low duty machinery tools like torquing tools
  • Low and medium duty pumps.

Angular contact ball bearing

Angular contact ball bearings are constructed with axially asymmetric races and able to bear higher thrust and radial load, while higher contact angles are kept around 40 degrees. Angular contact ball bearing can take radial load with high axial load, it is also used for combined load application. It may be used in pairs in “O”, that is back to back arrangement, ‘X’ for face to face arrangement and tandem arrangement. It can run at high speed, high accuracy with low noise. But axial displacement is not possible in it and it does not compensate for misalignment.
Angular contact ball bearing

Angular contact ball bearing

Applications


  •  High speed application
  • Gear boxes
  • Clutch system
  • Motorcycle over head system
  • Mills
  • Wind energy
  • Steel plants
What is the nominal angle for angular contact bearing?

Self aligning ball bearing
It consists of two rows for the ball with a common spherical outer race, and a cage is between the inner and outer race of the bearing. In the self aligning ball bearing inner ring have two raceways. The self aligning ball bearing is recommended when the machine shaft can be bent during operation and housing deformation, or the alignment between shaft and housing is difficult, and it creates less friction than other types of bearing. This type of bearing with the taper bore that's why it is easily fits in the shaft with the adapter assembly.
Self aligning ball bearing
Self aligning ball bearing


Application

  • Textile
  • Mining
  • Heavy machinery
  • Power machinery
  • Agriculture
  • Liquid ring compressor

Types of roller bearing

  • Cylindrical roller bearing
  • Spherical roller bearing
  • Needle roller bearing
  • Taper roller bearing


Cylindrical roller bearing

there are many types of cylindrical roller bearing are use. but single row cylindrical roller bearing are mostly use, cylindrical roller bearing takes more space as compare to other type of bearing during installation.
single row cylindrical (B.) have radial load carrying capacity is less. But double or multi row cylindrical roller bearing are used for carrying heavy radial load.
Cylindrical roller bearing

Cylindrical roller bearing

Application

  • In power generation
  • Oil field
  • Heavy duty gear box
  • Machine tools transmission
  • Vibration machine
  • Trains wheels
  • And other types of heavy redial loads machinery.








Taper roller bearing

It is constructed with taper inner and outer raceways. The inner and outer ring is separated by the taper roller it is used in tight fitting arrangement. When used in pairs arrangement, proper internal clearances and preload can be set by adjusting the distance between two bearing inner and outer rings. Designed to accumulate the combined load, the axial load carrying capacity of the bearing depends on the contact angle between raceway and rollers. It means that the larger the contact angle, the capacity to bear the axial load is large (heavy).
Taper roller bearing

Taper roller bearing


Applications 

  • Mostly use for combined load
  • It is use in face-to-face, back-to-back or in tandem
  • Gear box
  • Overhead hoisting equipment
  • Mining equipment
  • Rolling mills


Spherical roller bearing

It is a types of rolling element bearing and used for heavy heavy radial and axial load applications. It can bear more angular misalignment as compared to others. Spherical roller bearing consists of the outer ring having a continuous spherical raceway. Within that spherical race, two rows of barrel-shaped rollers are operate. 
This barrel-shaped roller is intended to be guided by an inner ring raceway. But misalignment and shaft deflection is a big challenge for Spherical roller bearing because it can not bear more misalignment and shaft deflection for prevent this type of problems use with combination of spherical roller bearing. Spherical roller bearing is used in two combinations. single row Spherical roller bearing, and double Spherical roller bearing as per required application.
Spherical roller bearing

Spherical roller bearing


    Application

    • Use in equipment for shock resistance 
    • Use for bear heavy load due to it ring arrangement
    • Heavy gear box
    • Turbine
    • Compressor and mining equipment
    • Mechanical fan
    • Construction equipment 


    Needle roller bearing

    This is a type of roller bearing.  In this type of bearing very thin cylindrical rollers are used. The number of rollers used in this bearing is more than other types of roller bearing, so the radial load carrying capacity is also more. It is used as an interchange of sliding bearings. The Needle roller bearing is available in many types of arrangement like, single row, double row, and split case.
    Needle roller bearing

    Needle roller bearing




      Application

      • Rocker arm pivot
      • Power transmission
      • Pump
      • Compressor