Micrometer: Its Working Principle, Parts, Use And Precautions

Mitutoyo micrometers

 

A micrometer is used for measurements that require greater precision than a caliper. Though micrometers gives superior precision, it can only measure a very small length. It consists of a calibrated screw that which when rotates helps in giving an accurate measurement.

Reading measurements in a micrometer is not at all a difficult task. With a little care and precaution, one can learn to take the measurements easily. If you want a buy a good micrometer, Mitutoyo micrometers are really good.

Principle of Operation

The basic principle of operation of a micrometer is as follows:

  1. The amount of axial movement of a screw that is made accurately can be measured by the amount of rotational movement of it. This is because the pitch of the screw is constant.
  2. The measurement made due to the rotational movement is some amplified form of the actual axial movement of the screw.

Parts

A micrometer has the following parts:

  • Frame: It is the C-shaped body that holds the anvil and the barrel together. This frame is heavy and thick which makes it difficult to strain under mechanical and thermal stresses.
  • Anvil: It is the part that rests on one side of the frame. Spindle moves towards the anvil when in order to hold the object and take the measurement.
  • Sleeves/barrel: The stationary cylindrical component that the frame holds on the other side of the anvil.
  • Lock nut/thimble lock: The lever which is used to tighten the movement of the spindle so that it doesn’t move while taking the measurement.
  • Screw: It is the main component on which the micrometer works and is hidden from the sight.
  • Spindle: The cylindrical component which moves when you rotate the thimble. This touches the object which is to be measured and holds it tight.
  • Thimble: It is the component which is turned by thumbs and which makes the spindle movement.
  • Ratchet stop: The device which is at the end of the instrument and is responsible for exerting only allowable pressure to the object and not more than that.

Care and proper use of a micrometer

Before you rotate the thimble or the ratchet knob, unlock the locking lever. Make sure to clean the measuring faces with the help of a clean cloth before you begin taking measurements. As you begin measuring, start rotating the ratchet knob and not the thimble. The ratchet knob will ensure you do not over tighten the thimble as that will not only give an erroneous reading but can damage the instrument too.

It is also advisable that you do not keep the instrument in the Sun for long. The horizontal line on the sleeve should be aligned to zero when the when the micrometer is at minimum reading. In case it does not happen, the micrometer will be needed to calibrated. For calibration, each device comes with a half-moon adjusting wrench.

Remember to use the thimble lock while micrometer is still holding the object. If you do not do this, the spindle might move a little while taking the reading or taking the object off from the micrometer. Write the measurement when the lock is on and if you haven’t written it and taken the object out, redo the measurement.

Micrometer finds its use in almost all manufacturing industries. They can also be mounted on a bedways of the lathe or similar machine tools to make the measurements accurate and easy.

11 Types Of Machines Used In Metal Working Industries

Metalworking industries employ a wide range of machine tools to create parts that are of a desired shape and size. These machines have evolved over the past hundreds of years and have made it possible to produce not only the most complex shapes but also in a way that involves very less human effort.

machine-tools

There are various techniques used by the fabrication industry that has led to invention and evolution of many machines. Following are the most widely used machines in the metalworking industry:

  1. Lathe Machine: These are the machines that rotate the workpiece to perform various machining operations. Lathes can be used to produce parts that are ferrous, non-ferrous metals, plastics, and wood. They are multipurpose machines that can be used to perform operations like cutting, sanding, knurling, drilling, boring, threading, facing and turning. They come in various sizes, and with a range of accessories.
  2. Milling Machine: It is a machine that uses rotary cutters to remove the undesired material. The workpiece is held tight on the movable worktable and a rotating tool is made to move vertically. The two major operations that a milling machine performs is face milling and peripheral milling.
  3. Grinding Machine: In this machine, an abrasive wheel is made to rotate at relatively high speeds. The rotating wheel provides finishing to the workpiece by removing a very small amount of material along its surface, after which it becomes smooth to touch.
  4. Drilling Machines: These are one of the most common types of machines that we can see around us. They are used for various household repair works too. The tools of this machine are easy to install and replace which makes it really easy to use. They can be used for making a hole in a wide range of materials which not only includes metals but also materials like cement and concrete.
  5. Shaper Machines: It uses a single point cutting tool that moves in a linear motion to perform a cutting operation on a workpiece. It has a simple mechanism and is easy to operate too.
  6. Broaching Machine: It uses a toothed tool or a broach to remove material from the workpiece. There are two types of broaching processes – linear and rotary.
  7. Saw machines: There are three types of saw machines, hacksaw, circular saw and band saw. These machines are used to cut a metal piece into two. It uses a blade which is either rotating or reciprocating to make the cut.
  8. Planer Machine: This machine is very similar to shaper machine and the only difference in this machine is, the cutting tool is stationary and the workpiece is made to move in a linear motion. Generally, these machines are larger than shaper machines.
  9. Shearing Machine: It is a machine that is used for cutting sheet metal. Shearing process does not form chips or any residual material. Other major metal cutting operations that are similar to this are blanking and piercing.
  10. Hobbing Machines: These machines are used for making gears and splines. It is a type of milling machine that uses a special type of cutting tool but is relatively inexpensive and is mostly used to produce spur gears.
  11. Drill Press: It is a more reliable version of a hand-held drill as they have better stability than them. The workbench allows the drills to be made continuously with good accuracy.

These are the most common machines used for metal cutting and shaping operation in metalworking industries. Special purpose machines are also made for performing some specific operations on a specific product. These machines are used for increasing the production rate.

In last couple of decades, many new technologies have come up that involves advanced techniques to produce articles that are not only of complex shapes, but also that produces less amount of waste materials.