Theory of Machines · 29/08/2021 1

Cam And Follower Mechanisms | 10 Unconventional Knowledge About Cam And Follower That You Can’t Learn From Books.

What is the purpose of a cam and follower?

Cam and follower mechanisms are profiled shapes that are placed on a shaft and are responsible for the movement of a lever or follower. In order to transform rotational motion into linear (reciprocating) motion, cams are employed. The follower rises and falls in response to the rotation of the cam, which is referred to as reciprocating motion.

cam and follower

When two links are linked together either along a line or at a point, the connection is referred to as a higher pair. A whole cam and follower system will be comprised of two upper pair devices of this kind. A higher pair mechanism is referred to as a cam and follower mechanism.

Because the smooth operation of a cam and follower mechanism is critical to its efficiency, it is critical that the follower move smoothly without needing excessive input power, which implies that the follower should not jam during its movement.

What does a cam and follower look like in practice?

A cam and follower is an integral part of a cam. Despite the fact that cams may be found in a variety of applications (dishwashers, sprinklers, and so on), the most well-known is the camshaft used in automobiles. In order to transform rotational motion into linear motion, a cam must be used.

All of these timing actions may be readily set by using cam and follower mechanisms in an IC engine since the valves must be maintained open at first, then closed and remained closed. As an example, we may look at planar links, two-dimensional linkages, and other types of connections.

What is the difference between the cam and the follower?

Cams are reciprocating, oscillating, or rotating bodies that are in touch with another body, known as the follower, and which impart reciprocating or oscillating motion to the follower while in contact with it. Because of the cam’s own motion, the necessary motion of the follower, and the form of the contact face of the follower, the shape of the cam is determined by these factors.

Then we’ll talk about the many kinds of Cam.

CAMs are classified into the following categories:

There are many different kinds of cams available, which are mentioned below: 

• Disc or Plate Cam

• Cylindrical Cam

• Translating Cam

• Radial Cam

• Wedge Cam

• Spiral cam

• Heart shaped cam

• Conjugate cam

• Globoidal cam

• Spherical cam

Disc or Plate Cam:

An axial disc or plate cam is a kind of cam in which the follower travels radially outward from the cam’s rotational center, as opposed to a radial plate cam. These cams are very popular because of their simple design and small size, which allows them to be installed in distant locations. Disc or Plate Cams are used in IC engines and machine tools, to name a few examples.

01 PLATE CAM or DISC CAM AND FOLLOWER MECHANISM ANIMATION | Cam And Follower Mechanisms | 10 Unconventional Knowledge About Cam And Follower That You Can't Learn From Books. | cam and follower

In order to give a particular motion to the follower, the disc (or plate) cam is designed with an uneven shape. The follower spins on a plane that travels in the direction of the camshafts axis of rotation, and it is held in touch with the cam by either springs or gravity.

Cylindrical Cam

A cylindrical cam is a kind of cam in which the cylinder rotates around its axis and has a circumferential groove contour carved into the surface of the cylindrical body during the rotation process of the cylinder. They are also classified into two types: the first kind has a circumferential groove carved into the surface of the cam and the roller, and it has a positive oscillating action which is parallel to the axis of rotation of the cylinder. As in the second type, a cylindrical surface may be used as a working surface. When using this kind of cam, the follower is spring-loaded and moves along the parallel axis with the spinning cylinder.

01 CYLINDRICAL CAM AND FOLLOWER MECHANISM | Cam And Follower Mechanisms | 10 Unconventional Knowledge About Cam And Follower That You Can't Learn From Books. | cam and follower

Translating Cam

The kind of cam in which the cam may move in a horizontal plane is made up of a curved plate with grooves or contours that slides on a guiding surface is known as a translating cam. The follower should oscillate or reciprocate is also connected, and the motion of the follower is restricted with the aid of the spring. Groove or contour cams, in which the follower motion is accomplished without the need of a spring, are often employed.

01 translating cam and follower mechanism | Cam And Follower Mechanisms | 10 Unconventional Knowledge About Cam And Follower That You Can't Learn From Books. | cam and follower

Radial Cam:

This is a cam that rotates along a radial axis. If the input link, also known as the cam, rotates as angular motion, then the cam has rotational or angular motion, and we refer to it as a radial cam.

The cam is the name given to this profiled body. A revolute pair connects the foundation to the fixed link, which is also known as the fixed link. Cam is the pivotal link in the chain. The fixed link and cam are connected by a revolute pair, and the follower is connected to the output link via the follower. If this cam rotates in accordance with the profile or form of the cam, the follower will experience translatory motion in conjunction with this prismatic pair between the fixed link and the follower, as shown in the illustration.

As a result, the oscillation of the follower and guide will be caused by the uniform rotational motion of this cam.

01 radial cam | Cam And Follower Mechanisms | 10 Unconventional Knowledge About Cam And Follower That You Can't Learn From Books. | cam and follower

Wedge Cam:

If the cam moves in a linear way, it is referred to as a wedge cam. The wedge cam features a four-link system, the first of which is the fixed link, and the other of which is the cam that looks like a wedge. According to the profile of this wedge, when this cam oscillates in the horizontal direction, the follower will oscillate in the vertical direction, along with this prismatic pair or this guide, depending on the configuration of this wedge.

01 wedge cam | Cam And Follower Mechanisms | 10 Unconventional Knowledge About Cam And Follower That You Can't Learn From Books. | cam and follower

The wedge cam has an inclined flat regular shape that imparts a particular motion to the follower when it is in the closed position.

Spiral Cam:

When the spiral cam is used to form the Grooved contour, it comprises of a semicircular or a spiral that travels in a reciprocating motion while the follower moves perpendicular to the cam’s axis.

01 spiral cam and follower mechanism | Cam And Follower Mechanisms | 10 Unconventional Knowledge About Cam And Follower That You Can't Learn From Books. | cam and follower

Cam with a heart-shape:

This kind of cam has the appearance of an asymmetric heart. It is mostly used to return a shaft to a predetermined position in order to keep the cam in that place due to the pressure exerted by a roller.

Conjugate Cam:

A cam profile is formed by connecting two discs to each other and shifting the axes of the discs apart by a predetermined distance from one another. Two rollers on the follower make surface contact with the cam profile of the follower. As the cam spins, followers move in lockstep with it.

Globoidal Cams:

A globoidal cam is a shaft with a circumference that is either concave or convex. A groove is created by machining on the surface of the follower, and this groove is used to provide movement to the follower. An oscillating follower around a fixed point is achieved using a globoidal cam.

What is the definition of a Follower?

A follower is a mechanical component that moves in the same direction as the cam. It may be either translating or oscillating. It may be in contact with the cam’s surface profile or it might be spring-loaded. It may move with uniform velocity or with uniform acceleration motion, depending on the situation. With the assistance of the follower motion, it is possible to create complicated output motion.

01 different types of follower ends and their uses | Cam And Follower Mechanisms | 10 Unconventional Knowledge About Cam And Follower That You Can't Learn From Books. | cam and follower

Followers may be classified into the following categories:

There are many distinct types of surface contact between the cam and follower, and they are categorized as follows based on the kind of surface contact:

• Movement-based follower types

• Shape-based follower types

• Follower types based on movement direction

Movement-based follower types

The relative motion and movement between the cam and follower are categorized as follows.

1) Translatory Motion

Translational motion is achieved by the follower in this case, meaning that the cam is rotating and the follower reciprocates between the guide ways. Followers of this kind include the knife edge follower, the roller follower, the flat follower, and the spherical follower, to name a few examples.

2) Oscillatory Motion

When using this kind of follower, the follower moves in an oscillating manner. The cam rotates, and the follower moves in accordance with the cam profile, but the follower is fixed at the position around which the follower oscillates. The oscillatory motion type follower is the name given to this kind of follower.

Shape-based follower types

The following are the four distinct kinds of followers:

  • Linear followers
  • Oscillating followers
  • Knife edge followers
  • Roller followers
  • Followers with a flat face or a mushroom form
  • Followers with a spherical face

Linear follower

It is known as a translating follower if the follower moves linearly rather than angularly. When it comes to the translating follower, which is defined as the axis of that prismatic pair passing through the cam center, we refer to it as radially translating follower. When the follower axis crosses through the center of the camshaft, the follower is referred to as a radial translating follower. The term “offset translating follower” refers to the fact that the axis of the translation of the follower does not cross through the center of the cam.

Oscillating follower

The cam continues to spin in the same manner as previously, but because of the form of the cam, the follower experiences oscillatory motion, and the follower is hinged at the place where the cam is hinged. As a result, this is referred to as an oscillating follower.

Knife-edge follower

If the follower only has a knife-edge contact with the cam, it is referred as as a knife-edge follower. Because of the very high wear rate, the knife-edge is merely theoretical due to the fact that the knife-edge follower is never utilized. There will be a great deal of contact stress.  This kind of follower makes direct touch with the cam and has a sharp contact area. T hese types of followers are not often used in the event of rapid application.

01 knife edge follower in cam mechanism | Cam And Follower Mechanisms | 10 Unconventional Knowledge About Cam And Follower That You Can't Learn From Books. | cam and follower

Roller follower

When a follower is hinged to a roller, and the roller comes into contact with the cam, the follower is known as a roller follower. This is the cam that rotates, and the follower that is hinged here oscillates in response to the rotation of the cam. It is used when a significant amount of force must be transferred, such as in stationary IC engines.

There must be sufficient space to accommodate a large roller because the pin must be large enough to transmit the force between the cam and the follower and the roller must be at least twice as large as the pin. If there is insufficient space for a large roller, the pin must be made substantially larger than the roller.

Because it makes a smooth touch with the surface, this kind of follower is mostly used in high-speed operations. When compared to the other types of followers, this kind of follower experiences less wear and tear.

Flat face follower:

The flat face follower is the name given to the follower surface that comes into contact with the cam and is in the shape of a flat surface. As an alternative to a flat surface, the follower surface may alternatively have a curved shape. Because it is the cam that rotates and the follower that is hinged here that oscillates, this is referred to as curved-face motion. Using a flat face follower, assuming space is limited and the force involved is not too great (like in the case of cars), may be an effective solution.

01 flat follower mechanism in cam and follower | Cam And Follower Mechanisms | 10 Unconventional Knowledge About Cam And Follower That You Can't Learn From Books. | cam and follower

This kind of follower has the appearance of a flat surface with an uneven cam, as seen in the illustration. This kind of cam is utilized when there is a limited amount of space available and the follower must withstand greater side thrust. It is also possible to utilize this follower in a critical situation.

Spherical Follower

This kind of follower features a bent yet normal follower, as well as a cam, which makes it quite versatile. This is a variation on the flat-faced follower design.

Follower types based on movement direction

1) Radial Follower

A follower with a center line of movement is one that is located directly in the middle of the camshaft. The majority of the time, the follower’s movement is in sync with the leader. The follower is in the midst of a reciprocating movement.

2) Offset Follower

If you have this kind of follower, the movement of the follower’s axis is not colinear with the movement of the cam axis.

Nomenclature for the Cam and Follower:

The following is the terminology used in the context of Cam and Follower:

• Trace Point

• Base Circle

• Prime Circle

• Pitch Curve

• Pressure Angle 

01 nomenclature of cam and follower mechanism | Cam And Follower Mechanisms | 10 Unconventional Knowledge About Cam And Follower That You Can't Learn From Books. | cam and follower

Trace point:

A trace point is a point on the follower that is used to explain the movement of the follower. It is the center of the roller in the case of a roller follower. In this case, the trace point is the roller centre, which implies that the follower’s movement will be described in terms of the motion of the roller center.

We utilize the tracepoint of a flat face follower when the follower is at one of the extreme positions, when follower is nearest to the cam center. If the follower has a curved face, we use the tracepoint of a point on the follower’s face that is in contact with the cam surface when the follower has a flat face. 

Base circle

We refer to this circle as a base circle because it’s the smallest circle that can be formed with the cam center as the center and contacting the cam profile; this circle is the smallest of all the circles that can be drawn. As a result, the radius of the base circle we designate Rb is referred to as the base circle radius.

Pitch curve

Consider the concept of kinematic inversion while defining the pitch curve. This is a four bar-link mechanism, consisting of a fixed link, a cam, a roller, and a follower, as seen in the kinematic inversion.

This link is fixed in this four-link mechanism, however it is not fixed in the kinematic chain if we do a kinematic inversion while keeping the cam fixed. If the location of the center of the roller is parallel to the cam profile, a curve will be generated by the roller.

After kinematic inversion with the cam fixed, this is the location of the trace point or roller center, as shown in the diagram.

Prime circle

A prime circle is the smallest circle that can be formed with the cam center as the center and with the pitch curve as the tangent to it.  The center of this circle is located on the camshaft axis and it is tangential to the pitch curve. This circle is referred to as the prime circle. If the base circle radius is Rb and the roller radius is Rr, then the prime circle radius is Rp = Rb + Rr.

Pressure angle: 

The global normal between the roller and the cam passes through the center of the roller and is perpendicular to the cam profile.

Assuming we ignore friction, the force that the cam puts on the rollers is in the direction of this standard normal. This is the direction of force between the cam and roller when there is no friction between these two components. However, since the roller is being pushed in this way in the vertical plane, the angle should not be too great. So the pressure angle is defined as the angle between these two directions, which is the normal contact force and the direction of the follower movement. This angle is represented by the symbol “φ”.

Obviously, in order to ensure smooth movement of the follower, the maximum value of φmax should be smaller than the φ value that is permitted. The value of φ varies based on the cam profile, and for a translating roller follower, the maximum value of φ should be less than 30 in most instances. While resisting the spring force, the pressure angle should be kept as low as possible, and this positive offset guarantees that the pressure angle decreases during the motion. While the follower is going down, it compresses the spring and increases the force applied to it.

Working Principle of the Cam and Follower:

A normal force acts in the X direction, and a normal force acts in the Y direction, and the cocking moment, which is the moment owing to this force Fn, is balanced by these two normal forces.

Because of this vertical motion, the friction force that will attempt to resist it will be three times the usual force. If we consider the normal force to be N, then this friction force will be μN. In order for the follower to go higher, it must not only resist these two friction forces, but it must also overcome the spring force.

It is necessary to have a large Fn in order to overcome the friction force, and the vertical component of the Fn will overcome both of these friction forces as well as the spring force. However, when the follower is moving downward, the spring force assists the follower in coming down, resulting in a smaller contact force.

In this case, Fn cos φ will be the vertical component, and if the value of φ is extremely high, then the vertical component will be decreased. Therefore, during the the upward movement, the pressure angle should be modest, while during the return movement, φ may be big, making φmax more important during the uphill movement than during the return movement.

When constructing a cam and follower system, it is important to ensure that the translating follower does not jam in the prismatic guide. The likelihood of the oscillating follower’s movement being restricted is greatly reduced.

Benefits of Cam and Follower

There are many benefits to using a cam and follower. 

• Cam and follower bearing are that they always distribute evenly, regardless of the configuration of the unit.

• When it comes to linear movements, cams and followers provide a broad variety of options.

• Cam and followers have the ability to absorb more stress than usual while also reducing distortion. 

• They are very flexible.

• Cam and followers have the ability to absorb more stress than usual while also reducing distortion. 

Disadvantages of using a cam and follower:

The following are some of the drawbacks of using Cam and Follower:

• The backlash between the cam and follower and the cam is measured in microns.

• This must be halted immediately in order to avoid extensive damage in the case of a machine accident.

• More costly to produce and machine because of the higher level of accuracy required.

• It is not feasible to have a negative radius of curvature.

Application of a cam and follower:

The following are examples of CAM and FOLLOWER applications:

• The feed mechanism of a lathe machine is an important part of the machine.

• The inlet and exhaust valves of an IC engine are have cam and follower.

• These are utilized in the manufacture of wall clocks.

• These are used in the automated lathe machine’s feed mechanism.

Screw machines and other items of equipment together.

Gear-Cutting Machineries are a kind of machine that cuts gears.

• In printing machinery, this device aids in the printing process by assisting the screen. The push aids in obtaining the location in which the printing will take place, and the pull aids in printing on that position.

• The primary mechanism in hydraulic systems is the piston.

• The Cam and Follower mechanism, which is also found in textile types of equipment, aids in the stitching of clothing by a push and pull to move.

• In this instance, the mechanism is reliant on the fluid pressure. Different types of equipment, such as cams and followers, are used in the production of various components that are automated in motion.

FAQs in Cam and Follower

What exactly are the terms cam and follower?

Cam and follower mechanisms are profiled shapes that are placed on a shaft and are responsible for the movement of a lever or follower. In order to transform rotational motion into linear (reciprocating) motion, cams are employed. The follower rises and falls in response to the rotation of the cam, which is referred to as reciprocating motion.

What is a Cam Mechanism, and how does it work?

A cam is a revolving or sliding component that is part of a mechanical linkage that is used to convert rotational motion into linear motion, in particular. An eccentric wheel (for example, an eccentric shaft) is a revolving wheel or shaft that hits a lever at one or more places along its circular route, usually near the end of the wheel or shaft (for example, an irregular cylinder).

What is the Follower Mechanism, and how does it work?

Cam and follower mechanisms are profiled shapes that are placed on a shaft and are responsible for the movement of a lever or follower. In order to transform rotational motion into linear (reciprocating) motion, cams are employed. It is either via the force of gravity or a spring that the follower maintains contact with the cam.

What exactly is Cam?

A cam is a rotating device that, via direct contact with the follower, which is another part of this machine, provides oscillating or reciprocating motion to it.

What is the definition of a Follower?

A follower is a spinning or oscillating component of a machine that follows the motion of a cam by making direct contact with the cam itself.

What is the function of a cam and follower in your system?

The intake and exhaust valves of an I C engine are operated by a cam and a follower, which are both extensively utilized. These are utilized in the manufacture of wall clocks. All of them are used in the automated lathe Machine’s feed mechanism. These are used in paper-cutting machines, among other things.

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