Mikrometrin

Mikrometrin, or micrometer screw gauge, is a precision instrument used to measure small distances with high accuracy. It is commonly employed in metalworking, manufacturing, and quality control to determine external dimensions such as diameters, thicknesses, and flatness with repeatable results.

A typical external micrometer consists of a rigid frame, a calibrated screw spindle, a stationary anvil, a graduated sleeve with a linear scale, and a rotating thimble with a circular scale. When the thimble is turned, the screw advances or retracts the spindle toward or away from the anvil. A ratchet mechanism provides a consistent measuring pressure to minimize user-dependent error. Internal micrometers and depth micrometers use similar principles but are designed for measuring inner holes or depths, often with non-rotating anvils or specialized adapters.

Measurement involves zeroing the instrument, placing the workpiece between the spindle and the anvil, and bringing them into contact with controlled force. Readings are taken by combining the main scale on the sleeve with the thimble scale. Some micrometers are analogue, while others include digital displays or absolute encoders for easier reading and data transfer.

Types and variants include external micrometers for external dimensions, internal micrometers for bores, depth micrometers for step and hole depths, and digital versions with enhanced readability. Most standard devices offer a least count of 0.01 mm (0.001 in), while high-precision models can resolve 0.001 mm.

Calibration and maintenance are essential for accuracy: use gauge blocks or calibration artifacts, check zero setting, keep measuring faces clean and dry, and store the instrument to prevent damage. Measurements are temperature sensitive, so measurements are typically performed at a controlled temperature and, when needed, temperature compensation is applied.