What Are Dial Indicators?

The dial indicator is a table-type universal length measuring tool made using a precision rack and pinion mechanism. It usually consists of a probe, a measuring rod, a shock-proof spring, a rack, a gear, a hairspring, a circular dial and a pointer.

Dial indicator

The dial indicator uses precision

The dial indicator was made by BC Ames in the United States in 1890. Commonly used for shape and position errors and length measurements with small displacements. The dial of the dial indicator is printed with 100 division marks, that is, each division value is equivalent to 0.01 mm of movement of the measuring rod ^[1]

The working principle of the dial indicator is to move the measuring rod in a small straight line caused by the measured size, and enlarge it by gear transmission to turn the pointer on the dial to read the size of the measured size. The dial indicator is a measuring instrument that uses a rack gear or lever gear drive to change the linear displacement of the measuring rod into the angular displacement of the pointer.

The structure of the dial indicator is relatively simple, the transmission mechanism is a gear train, the outline size is small, the weight is light, the transmission mechanism is small inertia, and the transmission is relatively large. It can use a circle scale and a large measurement range. Can also make absolute measurements.

Mainly used to measure the size and shape of the part, position error, etc. The division value is 0.01mm, and the measurement range is 0-3, 0-5, 0-10mm.

The structure of the dial indicator is mainly composed of three parts: the body part, the transmission system, and the reading device.

The layout of the dial indicator is relatively simple, the transmission organization is a gear train, and the outline dimensions

The dial indicator has implemented the export product quality permit system, and products that have not obtained an export quality permit are not allowed to be exported.

The dial indicator is a comparatively accurate measuring tool. It can measure both relative and absolute values. It is mainly used to measure the shape and position error, and it can also be used for precision calibration when installing workpieces on machine tools. The accuracy of the dial indicator is 0.01mm. The structural principle of the dial indicator is shown in Figure 1. When the measuring rod 1 is moved up or down by 1 mm, the large pointer 5 is caused to make one rotation and the small pointer 7 is caused to make one division through the gear transmission system. The scale has 100 equal divisions on the circumference, and the reading value of each division is 0.01mm. The small pointer reads 1mm per division. The amount of change in the pointer reading during measurement is the amount of dimensional change. The dial can be rotated so that the large pointer is aligned with the zero ruled line when measuring.

The dial indicator reading method is: read the small pointer first

1) Before use, check the flexibility of the measuring rod movement. That is, when the measuring rod is gently pushed, the movement of the measuring rod in the sleeve must be flexible without any sticking phenomenon. After each hand is released, the pointer can return to the original scale position.

2) During use, the dial indicator must be fixed on a reliable holding frame. Don't be eager to save trouble, and clip it in an unstable place, otherwise it will easily cause inaccurate measurement results or break the dial indicator.

3) When measuring, do not make the stroke of the measuring rod exceed its measuring range, do not make the head hit the workpiece suddenly, and do not use a dial indicator to measure the surface roughness or work with significant unevenness.

4) When measuring a plane, the measuring rod of the dial indicator should be perpendicular to the plane. When measuring a cylindrical workpiece, the measuring rod should be perpendicular to the center line of the workpiece.

5) For the convenience of reading, the large pointer is usually used to point to the zero position of the scale before measurement. ^[2]

A very important application of dial indicator is to measure the shape

maintenance

1. Keep away from liquids and prevent coolant, cutting fluid, water or oil from coming into contact with the inside diameter gauge.

2. When not in use, take off the dial indicator so that the meter releases all its loads and leave the measuring rod in a free state.

3. Store the complete set in the box to avoid loss and mixing.