Cam and Follower: Types, Working Principle, Applications & Advantages

 

Have you observed the movement of the needle in the sewing machine? The. periodic to and fro or up and down motion of the needle is called reciprocating. It is a unique mechanism that can be seen in controlling the opening and closing of valves in IC(Internal Combustion) engines. 

 

What Is a Cam and Follower Mechanism?

The cam and follower is a mechanical device used to achieve the desired reciprocating motion. The cam is the rotating member, and the follower is the reciprocating member. The cam is a profiled disc, cylinder or sphere that rotates. The shape or profile of the cam influences the motion of the follower. The follower is a rod that is in contact with the cam. The contact between the cam and follower is achieved using spring or the follower's weight.

 

The cam and follower device consists of three members in it.

1. Cam - Driving member
2. Follower - Driven member
3. Frame - Supporting member

 

 

As the cam rotates, its varying cross-section makes the follower in contact with it to reciprocate. The frame or guide guides the follower while reciprocating and acts as a support for the cam and follower.

 

Types of Cam and Followers

Cams and followers can be classified into many types. Let us have a look at it.

 

Types of Cam Based on the Shape

The cam can be classified into:

 

• Radial Cam: A flat plate or disc is carved and is used as a cam to obtain the required motion of the follower. In this type, the motion of the follower is perpendicular to the axis of rotation of the cam.

• Cylindrical Cam: This cam is cylindrical in shape, and there is a groove cut on its surface. The follower moves along the path of the groove. In this type, the motion of the follower is parallel to the axis of rotation of the cam.

• Wedge Cam: The cam is in the shape of a wedge and has a sliding motion. The follower moves up and down as the cam moves to and fro. Here the motion of the cam and follower are perpendicular to each other.

• Conjugate Cam: Two rollers are connected to the follower in this cam. Both rollers restrict the motion of each other, and this type of cam is used primarily for noiseless operation.

• Globoidal Cam: Globiodal cam is similar to cylindrical cam as they both have a groove cut. The difference is that the surface of the globoidal cam is either concave or convex.

• Spherical Cam: The spherical cam also has a groove cut in it, and here, the cam is in the shape of a sphere.

 

Types of Followers

Like cam, the followers can be classified into many types based on their shape, positions, and type of motion.

 

Based on the Shape

 

• Knife Edge Follower: This follower has a pointed tip in contact with the cam. The pointed tip causes wear and tear in the cam.

• Roller Follower: To overcome the defect of knife-edge followers, roller followers are used. In this, a roller is attached to the tip of the follower to make contact with the cam. It reduces the friction as well as wear and tear of the cam.

• Flat-Faced Follower: The follower has a flat surface to make contact with the cam. This is used when a quick motion is needed, but it develops a high surface tension during misalignment and deflection.

• Spherical Faced Follower: Spherical followers are used to overcome the difficulty of flat-faced followers. Here, the contact area is spherical, resulting in lesser wear and tension.

 

Based on the Position

 

• Inline Follower: In inline follower, the axis of the follower coincides with the centre of the cam.

• Offset Follower: In offset follower, the follower's axis is slightly away or at an offset from the centre of the cam.

 

Based on the Motion

 

• Translating Follower: If the motion of the cam is in a straight line, it is called a translating follower.

• Oscillating Follower: If the follower is pivoted, it follows an oscillating motion. Such followers are called oscillating followers.

 

 

Pros and Cons of Cam and Follower Mechanism

The following are the advantages of the cam and follower mechanism.

• It is a simple mechanism that converts rotary motion to reciprocating motion.
• With proper design, any desired motion of the follower can be achieved.
• This set-up can bear high vibrations.
• They are accurate and versatile.

 

The following are the disadvantages of the cam and follower mechanism.

• The cam is often subjected to wear and tear.
• The manufacturing cost is high and it must be precise.
• The cam and follower setup consume more space.

 

Application of Cam and Follower

 

In IC Engines: The reciprocating motion of an IC engine's inlet and exhaust valves is achieved by the cam and follower mechanism. 

 

In Children Toys: This cam and follower mechanism is used in many toys where simple periodic motion is required. 

 

In Automatic Lathe Machines: The motion of tools in an automatic lathe machine is controlled by this mechanism. Also, the feed mechanism in lathe machines is done by the cam and follower mechanism.

 

Many types of research are still underway to promote the performance of the cam and follower mechanism. A student of Skill-Lync designed a simple cam and follower model in Hyper Works using 3D contact in 2019. He had achieved a curve-to-curve joint and successfully reduced the damping by implementing a phenomenon called lift-off. 

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