The outside micrometer is a commonly used precision measuring tool, but it is not all-encompassing. This article will thoroughly examine the measurement limitations of the micrometer and the precautions that need to be taken during use, helping you better understand and utilize this tool.
I. Measurement Range and Accuracy of Outside Micrometer
1. The outside micrometer is mainly used to measure the outer diameter of objects, such as cylinders and spheres. Its measurement range is usually 0-25mm, 25-50mm, 50-75mm, etc. The measurement range of different specifications of micrometers varies, and the accuracy is generally 0.01mm. Some high-precision micrometers can reach 0.001mm.
2. We need to select a micrometer with an appropriate measuring range based on the actual measured dimensions of the workpiece to ensure the accuracy of the measurement. Using a micrometer with an excessive measuring range to measure small-sized workpieces will increase errors, and vice versa.
1. Objects with excessively rough surfaces: If the surface of the object to be measured is too rough, such as the surface of a casting or an unprocessed blank, using an external micrometer for measurement will be difficult to find a stable measurement point, resulting in inaccurate measurement results and even damaging the measuring surface of the micrometer.
2. Non-circular objects: The design principle of the outside micrometer is based on circular objects. Therefore, it is not suitable for measuring the dimensions of non-circular objects such as squares, triangles, etc. For non-circular objects, we need to use other measuring tools, such as vernier calipers, height gauges, etc.
3. Soft or deformable objects: For objects made of rubber, plastic, etc., which are soft or prone to deformation, the measuring force applied using an external diameter micrometer may cause the object to deform, thereby affecting the accuracy of the measurement results. Such objects require more specialized measurement methods.
4. Objects with excessively high or low temperatures: Temperature affects the thermal expansion and contraction of metals. Therefore, when measuring objects with extremely high or low temperatures, directly using an outside micrometer will result in significant errors. We need to wait until the object's temperature stabilizes before conducting the measurement, or use other methods for measurement.
1. Before use, check if the zero position of the micrometer is accurate. If it is not, calibration is required.
2. During measurement, make sure that the micrometer is perpendicular to the surface of the object being measured. Avoid any inclination, as this will affect the measurement results.
3. Apply the appropriate measuring force. Excessive or insufficient measuring force will affect the measurement results. Generally, the suitable measuring force will be marked on the micrometer.
4. After the measurement is completed, the micrometer should be cleaned promptly and stored in a dry and ventilated place to prevent corrosion and damage.
1. If you need to measure the dimensions of non-circular objects, you can choose tools such as vernier calipers and height gauges.
2. If you need to measure soft or deformable objects, you can consider using non-contact measuring devices such as image measurement instruments.
3. If you need to measure objects with excessively high or low temperatures, you can use tools such as infrared thermometers for indirect measurement.
