Dial bore gauge is a tool used to measure the diameter of holes or the inner diameter of pipes, and it is one of the
important instruments for precise measurement. When conducting accurate measurements of the inner diameter,
it is crucial to consider when to take the larger value and when to take the smaller value. Correctly understanding
and applying the measurement techniques of an inside diameter gauge is essential for ensuring the qualification
and functionality of the measured components.
I. Principles for Measuring Inner Diameter
When using an inner diameter gauge, one should first understand the design requirements and functional needs
of the object being measured. Generally speaking, the size requirement of the inner diameter depends on the type of
fit between the hole and the component. For example, in cases of clearance fit, it is likely to prefer the larger value
of the inner diameter gauge; while in cases of transitional fit or interference fit, a smaller value may be required.
II. When to Take the Maximum Value
When we aim to maintain a certain assembly clearance or need to provide space for the lubricating oil film,
we should take the maximum value of the inner diameter gauge. For example, in the assembly of sliding bearings,
a certain gap is required to ensure the free rotation of the bearings and the fluidity of the lubricating oil.
At this time, the maximum allowable value of the hole should be measured.
III. When to Take the Minimum Value
In applications that require high-precision positioning or to ensure no relative movement between parts, the minimum
value of the inner diameter is usually taken. For example, in high-precision mechanical assembly, in order to ensure
the precise fit of the transmission components, an internal diameter gauge is used to accurately measure
the minimum size of the hole.
IV. Measurement Techniques
1. Before measurement, it is necessary to determine the measurement reference point to ensure the
concentricity and repeatability of the measurement.
2. During the measurement process, the multi-point measurement method is adopted to determine the size of the
measured hole. In the direction of the hole diameter, select at least three different angles for measurement,
and take the minimum or maximum value among them.
3. Ensure that the range and accuracy of the inner diameter gauge are in line with the requirements hole.
4. Pay attention to the influence of temperature on the measurement results and perform temperature
compensation if necessary.
