Comparators

Comparators

Introduction

Comparators play a crucial role in metrology and mechanical measurements. They are precision instruments used to compare the dimensions of a given object with a standard reference. This helps in determining the accuracy and quality of the object being measured. In this article, we will explore the different types of comparators and their working principles.

Mechanical Comparators

Mechanical comparators are the most commonly used type of comparators. They work on the principle of mechanical amplification of the displacement of a measuring spindle. There are several types of mechanical comparators:

  1. Dial Indicators: Dial indicators are simple mechanical devices that use a gear mechanism to amplify the linear displacement of a spindle. They are widely used in industries for dimensional measurements.

  2. Lever-Type Comparators: Lever-type comparators use a lever mechanism to amplify the displacement of the measuring spindle. They are highly accurate and commonly used in precision engineering.

  3. Johansson Mikrokator: The Johansson Mikrokator is a mechanical comparator that uses a differential screw mechanism to amplify the displacement of the measuring spindle. It is known for its high accuracy and is used in applications where precision is critical.

To use a mechanical comparator, follow these steps:

  1. Place the object to be measured on the measuring platform.
  2. Move the measuring spindle towards the object until it makes contact.
  3. Observe the dial or scale on the comparator to read the displacement.

Mechanical comparators find applications in various industries such as automotive, aerospace, and manufacturing. They are used for measuring dimensions, checking tolerances, and ensuring the quality of machined parts.

Advantages of mechanical comparators include their simplicity, durability, and cost-effectiveness. However, they may have limitations in terms of accuracy and resolution.

Electrical Comparators

Electrical comparators are another type of comparators commonly used in metrology. They work on the principle of converting mechanical displacement into an electrical signal for measurement. There are different types of electrical comparators:

  1. LVDT (Linear Variable Differential Transformer): LVDTs are widely used electrical comparators that convert linear displacement into an electrical signal. They offer high accuracy and are suitable for measuring small displacements.

  2. Capacitive Comparators: Capacitive comparators use changes in capacitance to measure displacement. They are highly sensitive and can measure both linear and angular displacements.

  3. Inductive Comparators: Inductive comparators use changes in inductance to measure displacement. They are commonly used in applications where high accuracy is required.

To use an electrical comparator, follow these steps:

  1. Connect the electrical comparator to a power source and the measuring instrument.
  2. Move the measuring spindle towards the object until it makes contact.
  3. Observe the electrical signal output and measure the displacement.

Electrical comparators find applications in industries such as electronics, semiconductor manufacturing, and precision engineering. They are used for measuring small displacements, checking the flatness of surfaces, and calibrating instruments.

Advantages of electrical comparators include their high accuracy, ability to measure small displacements, and compatibility with digital measurement systems. However, they may be more complex and expensive compared to mechanical comparators.

Pneumatic and Optical Comparators

Pneumatic and optical comparators are specialized types of comparators used for specific applications.

  1. Pneumatic Comparators: Pneumatic comparators use air pressure to measure displacement. They are commonly used in industries where contactless measurement is required, such as the measurement of soft materials or delicate objects.

  2. Optical Comparators: Optical comparators use optical principles to measure displacement. They project the image of the object onto a screen and magnify it for measurement. They are widely used in industries for measuring dimensions, angles, and contours.

To use a pneumatic or optical comparator, follow these steps:

  1. Set up the comparator and adjust the settings according to the measurement requirements.
  2. Place the object to be measured on the measuring platform.
  3. Observe the image or scale on the screen and measure the displacement.

Pneumatic and optical comparators find applications in industries such as automotive, aerospace, and quality control. They are used for measuring delicate objects, inspecting surface finish, and checking the accuracy of machined parts.

Advantages of pneumatic and optical comparators include their non-contact measurement capability, high magnification, and ability to measure complex shapes. However, they may have limitations in terms of resolution and accuracy.

Conclusion

In conclusion, comparators are essential tools in metrology and mechanical measurements. Mechanical comparators, such as dial indicators and lever-type comparators, are widely used for dimensional measurements. Electrical comparators, including LVDTs and capacitive comparators, offer high accuracy and are suitable for measuring small displacements. Pneumatic and optical comparators provide non-contact measurement capabilities and are used for delicate objects and complex shapes. Understanding the different types of comparators and their working principles is crucial for accurate and precise measurements in various industries.