Designing Cams and Followers

The design of a Cam and Follower Mechanism involves several key steps, ensuring that the motion profile is accurate and the system operates smoothly. The process includes defining motion requirements, selecting the type of cam and follower, determining the motion profile, and finalizing dimensions for manufacturing.

1. Define the Motion Requirements

Before designing the cam and follower, it is essential to determine:

• The type of motion needed (reciprocating, oscillating, or intermittent).
• The speed and acceleration of the follower.
• The stroke length (distance the follower moves).
• Whether the motion needs uniform, acceleration-based, or dwell phases.

2. Select the Type of Cam and Follower

Depending on the application, the type of cam and follower must be chosen:

• Cam Types: Plate (disk) cam, cylindrical cam, conjugate cam, etc.
• Follower Types: Knife-edge, roller, flat-faced, or mushroom follower.

Example:

• For high-speed engines, a roller follower is used to minimize wear and tear.
• For precision machinery, a flat-faced follower ensures smooth operation.

3. Design the Cam Profile

The cam profile determines how the follower moves. The following steps are followed:

1. Base Circle Determination:

• The base circle is the smallest circle that can be drawn on the cam profile.
• It is determined by the follower’s size and required displacement.

1. Follower Displacement Diagram:

• The displacement diagram is plotted, showing how the follower moves over one rotation of the cam.
• Different motion types can be applied, such as uniform velocity, simple harmonic motion (SHM), or cycloidal motion.

1. Constructing the Cam Profile:

• The cam profile is drawn based on the displacement diagram, considering the follower type and required motion.
• For a disk cam, radial distances from the cam center define the follower’s position at different angles.
• If using CAD software (SolidWorks, AutoCAD, or Fusion 360), the cam profile can be generated parametrically.

4. Check for Interference and Clearance

• Ensure that the follower does not interfere with other machine parts.
• Verify the follower’s roller diameter to prevent excessive stress.
• Check for proper camshaft support and lubrication to avoid excessive wear.

5. Manufacturing Considerations

• Material Selection: High-strength materials like hardened steel or brass are used for durability.
• Tolerance and Fit: Ensure proper fits between the cam, shaft, and follower for smooth motion.
• Lubrication System: Adequate lubrication reduces friction and wear, increasing longevity.