What is Micrometer?
- A micrometer is a precision measuring instrument, used to obtain very fine measurements and is available in metric and imperial versions. Metric micrometers typically measure in 0.01mm increments and imperial versions in 0.001 inches.
- The measurements they provide can be more accurate than those given by other measuring devices such as dial calipers or vernier calipers but depend very much on the user’s care.
Accuracy of the Micrometer
- The accuracy of the micrometer is confirmed to DIN 863
- Reference temperature – 20°C in accordance with DIN 863.
- Measuring force – The force exerted by the ratchet drive on the measuring faces shall be between 5 to 10 N.
Working Principles of a Micrometer
A micrometer works on the principle of a screw and a nut. It allows you an axial rotation of the barrel-like structure, also known as Thimble, which is used to measure the distance of the object. The screw of a micrometer is attached to the thimble, which is a concentrated cylinder, attached to the micrometer. The circumference of the thimble is divided into equal parts of the micrometer to get accurate results.
When a screw is tuned through a nut in a circular motion, its axial movement will be equal to the pitch of the screw which is used in the special micrometer. The degree of rotation of the screw will be directly or indirectly correlated to the absolute value of axial movement.
A given amount of axial movement can be amplified in the resulting circumferential direction by using the actual diameter of the screw. The axial value can be reduced and can increase the accuracy by decreasing the pitch of the screw thread. Certain types of micrometers can be used according to the need.
Types of Micrometers
There are two common types of micrometers and three types of special micrometers to know about:
Types of Common Micrometer
- Outside Micrometer
- Inside Micrometer
- Depth Micrometer
Outside Micrometer
An external micrometer (or outsider micrometer) is used to measure the outer surfaces of any component. It provides accurate measurements of the components and is a very common type of micrometers used in manufacturing industries.
- Mechanical(Analogue) outside Micrometer and Digital outside Micrometer
- The outside micrometer is the most commonly used type of micrometer
- It is used to measure external dimensions such as the outside diameter of an object.
Types of Outside micrometers
- Rotating Disc Micrometer
- Point Micrometer
- Tube Micrometer
- Non-Rotating Disc Micrometer
- Spline Micrometer
- Blade Micrometer
Inside micrometer
- Inside micrometers are used to measure inside dimensions like the inside diameter of a hole or tube.
- There are two types of inside micrometer: caliper-type inside micrometers and tubular and rod inside micrometers
Type of Inside micrometer
- Caliper –Type Inside Micrometer
- Three-point Inside Micrometer
- Inside Micrometer (Tubular Micrometer)
Depth Micrometer
- Depth micrometers are used to measure the depths of holes, slots, and steps.
- They come with a variety of interchangeable rods of different lengths so that they can be used to measure a range of depths
Final Remarks
Micrometers are the backbone of the mechanical industries and is used to calculate every measurement for the components used in the industries.
