What are micrometers? How do they work?

A micrometer is a tool that measures the size of a target by gripping it. Some models are capable of taking measurements in units of 1 mm. Unlike calipers, micrometers apply the Abbe principle, which allows them to offer more precise measurements.

Generally, the term "micromete r” refers to outside micrometers. However, there are also a variety of micrometers, suitable for various applications. There are also inside micrometers, bore micrometers, tube micrometers and depth micrometers. The measurement range is always 25 mm but varies according to the size of the frame (0 to 25 mm or 25 to 50 mm for example), it is therefore essential to use a micrometer adapted to the size of the target. Recently, micrometers have gone digital.

How does a digital micrometer work?

There are two types of micrometers on the market:analog and digital, which can be used for the different models of micrometers depending on the measurement to be made, external and internal parallels, external and internal cylinders, special cylindrical parts, and for the height and depth measurements. To help you adapt to the handling of the digital micrometer, I will explain how it works; So when you buy one of these instruments, have a helpful guide when you are going to use it.

How do I measure with a digital micrometer?

A digital micrometer is a portable tool, with which it is possible to carry out very precise measurements of lengths between its two measurement contacts, with an accuracy of up to one thousandth of a millimeter, being able to express the measurement value in mm or in inches.

Digital micrometers are mainly used to perform measurements in the industrial field, or in dimensional metrology laboratories. They include a measurement range of 25mm to over one (01) meter and their standard resolution is 0.01mm, although they can handle resolutions of 0.001mm (0.0005 inches).

How a digital micrometer works

The way to make measurements with a digital micrometer is the same as in those that are analog; but, in the digital models, these have an LCD screen, where a direct reading is displayed, indicating the exact value of the measurement digitally. Some models also have the scales engraved on their structure.

The working principle of the digital micrometer is similar to that of a screw and a nut. Rotation of the ratchet causes an axial movement that advances the spindle 50 hundredths for each complete rotation (360 degrees). Also know the parts of a digital micrometer and check that yours is complete.

Tips and recommendations before, during and after using the digital micrometer

Before making the measurement, the anvil and spindle surfaces should be cleaned with a clean cloth to remove dirt and dust from these points; thus, we achieve accurate measurement results. We must not use organic solvents such as acetone or benzene to clean it.

• Before using the micrometer, we need to thermally stabilize it at room temperature.
• Do not exert excessive force on the instrument; stops should never be adjusted relative to the object being measured, using the drum; this should only be used to bring the plates closer to the object and then complete the measurement with the ratchet button.
• The instrument should only be held by the thermal insulation plates present on the body. It should never be taken by the extremities, as body heat will expand the metal, causing the distance and measurement to be altered.
• Do not remove the part between the stops without first separating them from them, otherwise it could force them, causing scratches on the plates, thus losing the calibration of the instrument.
• Do not use the instrument near magnetic fields or high voltage areas.
• Do not expose the micrometers to direct heat, excessive humidity, or corrosive environments or with airborne particles, keep them in their respective cases for better preservation.
• It is recommended to clean the instrument frequently, using a cotton cloth and a neutral cleaning product, avoiding that the product penetrates inside the mechanism .
• The recommended calibration interval for micrometers is 3 months to 1 year.

Method of measurement with a digital micrometer

• The measurement procedure is direct, placing the part or object to be measured between the anvil and the spindle.
• The micrometer should be held by holding the frame by the thermal insulation plate with the thumb and index finger of the left hand.
• First we place the piece we want to calibrate against the anvil's backing point, then we proceed to rotate the drum to bring the pin or tenon closer to the object.
• When the pin or pin is close to the object, with the index finger and thumb of the right hand, we turn the ratchet knob until it comes into contact with the body we are measuring, until it is completely clamped between the anvil or fixed stop and spindle.
• At the previous point, we continue to gently turn the ratchet knob until we hear three clicks, which will indicate to stop turning the ratchet.
• When the anvil and the spindle have firmly trapped the object we are measuring, we will fix the measurement obtained using the lever or the fixing or brake nut, thus avoiding that the reading taken is altered by an unwanted movement which causes a measurement error.
• As soon as we have locked the micrometer, we proceed with the reading on the screen, being able to compare it with the measurement recorded by the instrument on the scales, in case it has them.
• Finally, the brake lever is unlocked and the drum is turned in the opposite direction to release the object from the micrometer without causing any alterations to the instrument.