# Analysis of measurement error of reamer cutting diameter

09 July 2021

The reamer is a cutting tool for semi-finishing and finishing of holes. The cutting allowance is very small. The cutting process is actually a combined action of cutting and squeezing, and the tolerance zone in the diameter direction is generally very small. After the reamer is manufactured, it is worth discussing whether the cutting diameter of the reamer is within the qualified size range.

The influencing factors of the error in measuring the diameter of the reamer on the cylindrical blade

The reamer is used to ensure the surface quality of the hole wall of the aperture. It cannot guarantee the position of the hole. The function of the cylindrical blade of the reamer is to make the reamer squeeze the hole wall and guide and calibrate the processed aperture when it is working. Ensure the hole diameter and surface quality, basically no cutting effect. The cylindrical blade size f (see Figure 1) is generally controlled within 0.15～0.25mm. When the cylindrical blade is narrow, the squeezing effect is not obvious; when the cylindrical blade is wide, the torque is too large, and there is a danger of gnawing and vibration, but it is reduced. The effect of squeezing and ironing. Then when the true working diameter is accurately measured on the arc surface of about 0.15mm, there will be a potential error (see Figure 2): the longest of the two concentric circles (large circle and small circle) A straight line is a diameter. Except for the diameter, the distance between any two points on the circumference is the chord length, and any chord length is shorter than the diameter, that is, AA0<BB0, CC0<BB0, A1A2<B1B2, and C1C2<B1B2.

When we measure the diameter of the reamer, we generally use a centimeter or a micrometer. The result of the measurement should be that if the connection between the two blades passes through the axis of the reamer, the diameter is measured; if the connection between the two blades Without passing through the axis, the measured distance between the two blades can only be the chord length, not the working diameter of the reame.

Error table of distance between two blades and diameter of reamer

 Eccentricity/mm Difference between chord and diameter (at 20mm) Difference between chord and diameter (at 20mm) Difference between chord and diameter (at 20mm) 0.05 -0.00025 -0.0005 -0.001 0.1 -0.001 -0.002 -0.004 0.2 -0.004 -0.008 -0.016 0.3 -0.009 -0.018 -0.036 0.4 -0.016 -0.032 -0.06