Micrometers
Micrometers, aside from calipers, are the most commonly used handheld measuring tools. Mahr's micrometers are renowned for their high quality and compact design, ensuring user-friendly and reliable measurements. The micrometers feature high-quality ground spindles, carbide-tipped measuring faces, and a robust frame. The Micromar EWR series micrometers are equipped with the Mahr tolerance function, which enhances quality control even further. The EWR series micrometers are designed to operate in demanding conditions, backed by an IP65 protection rating. Discover Mahr micrometers in our online store.
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Micrometers
A micrometer, along with a caliper, is one of the most common handheld measuring tools in machine shops. A micrometer can measure with a precision of 0.01, making it well-suited for measuring ISO tolerances commonly used in machining. There are several models of micrometers, with the most common being the frame micrometer and the three-point micrometer. The frame micrometer is designed for measuring external distances, such as the outer diameters of shafts. Frame micrometers are available with a variety of measurement tips such as curved or round measuring tips, disk micrometers with disk-shaped measuring tips, thread micrometers with interchangeable measurement tips, and frame micrometers with narrowed measurement tips for measuring narrow grooves. The most common sizes for frame micrometers are 0-25mm, 25-50mm, 50-75mm, and 75-100mm, but they are also available in larger sizes. Three-point micrometers are used to measure the internal diameters of holes and can easily reveal the triangularity of a hole. Internal dimensions can also be measured with two-point internal micrometers and rod micrometers, which can be used to measure the ovality of holes. Other typical micrometers include, for example, depth micrometers.
All micrometers are based on a screw thread, designed such that the screw moves the movable measuring jaw either one millimeter or half a millimeter in a single rotation. The micrometer based on screw pitch was developed in 1772 by the Scottish inventor James Watt. The micrometer screw is turned by rotating the measuring drum, from which the measurement reading is also taken in analog micrometers. The micrometer end has a friction screw, known as a "ratchet," which ensures consistent measuring force during the measuring process. The micrometer's frame is always equipped with a plastic insulator to handle the measuring tool, preventing the warmth of the operator's hands from transferring to the measuring tool and causing thermal expansion. The measurement surfaces of a micrometer are usually made of either carbide or hardened and ground steel.
Modern digital micrometers are easy to read and can come with several advanced features, such as wireless data transmission or other functions like the built-in tolerance function in Mahr's Micromar, which immediately indicates if a measured value is within the specified limits.
Parts of a Micrometer
The parts of an analog micrometer equipped with a vernier scale are:
- Frame
- Anvil
- Measurement faces
- Spindle
- Sleeve
- Heat insulator plate
- Datum line
- Sleeve measuring scale
- Thimble measuring scale
- Thimble
- Adjustment screw (ratchet)
