Block gauge- B Measuring face Fig. 3-3 Measurement of the gauge block thickness by a...

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Block gauge- B Measuring face 測定面 Fig. 3-3 Measurement of the gauge block thickness by a micrometer 3.3 An example of the evaluation of measurement uncertainty (calibration of a micrometer) A micrometer (Fig. 3-3) is an instrument that can measure the length of a measurement target easily and precisely. What follows is an evaluation of the measurement uncertainty of a micrometer calibrated by using several block gauges with calibration certificates. We assume that the measurement will be carried out under the following conditions: - Calibration is carried out in an air-conditioned room at a temperature of 23C (with a deviation of ±0.5C). The measurement range runs from 0 mm to 25 mm. The measurement resolution of the micrometer is 0.001 mm. - The nominal dimensions of the block gauges range from 3 mm to 25 mm. - Each block gauge has a calibration certificate for temperatures under 20°C. Source of uncertainty 不確かさ要因 Repeatability of reading 測定の繰り返し精度 Resolution of instruments. 測定分解能 Uncertainty of gauge block ゲージブロックの不 確かさ Coefficient of thermal expansion 熱膨張係数 Temperature deviation 温度の揺らぎ Symbol 記号 Xi u (Rpt) A u (Res) u (G₂0) Type タイプ AIR) B B B u (ATIR) B Table 3-1 Uncertainty budget table Uncertainty Probability value distribution 不確かさ値 確率分布 0.001 mm 0.1 μm +2x10-6 /°º℃ ±0.5 °℃ Rectangular 一樣分布 Normal 正規分布 Rectangular 一樣分布 Rectangular 一樣分布 Combined uncertainty uc 合成不確かさ Divisor 除数 √12 2 √3 √3 Expanded uncertainty Uc (k=2, 95% confidence) 拡張不確かさ Standard Sensitivity uncertainty coefficient |cx|ul 標準不確かさ 感度係数 u (x₁) um C₁ 0.333 μm 0.289 μπ 0.050 μm 1.154x10-6 /°℃ 0.289 C 1 1 -1 - 12.5004 mm'℃ -0.00028 mm/℃ 0.333 0.289 0.050 0.014 0.081 0.451 um 0.90 μm 304 Build up the uncertainty budget table The calculation results and procedure are summarized as the uncertainty budget table shown in Table 3-1. 3-1) Calculate how much you can reduce the measurement uncertainty by increasing the number of replicated measurements to 16 based on the same standard deviation in Section 3.3. Block gauge- B Measuring face 測定面 Fig. 3-3 Measurement of the gauge block thickness by a micrometer 3.3 An example of the evaluation of measurement uncertainty (calibration of a micrometer) A micrometer (Fig. 3-3) is an instrument that can measure the length of a measurement target easily and precisely. What follows is an evaluation of the measurement uncertainty of a micrometer calibrated by using several block gauges with calibration certificates. We assume that the measurement will be carried out under the following conditions: - Calibration is carried out in an air-conditioned room at a temperature of 23C (with a deviation of ±0.5C). The measurement range runs from 0 mm to 25 mm. The measurement resolution of the micrometer is 0.001 mm. - The nominal dimensions of the block gauges range from 3 mm to 25 mm. - Each block gauge has a calibration certificate for temperatures under 20°C. Source of uncertainty 不確かさ要因 Repeatability of reading 測定の繰り返し精度 Resolution of instruments. 測定分解能 Uncertainty of gauge block ゲージブロックの不 確かさ Coefficient of thermal expansion 熱膨張係数 Temperature deviation 温度の揺らぎ Symbol 記号 Xi u (Rpt) A u (Res) u (G₂0) Type タイプ AIR) B B B u (ATIR) B Table 3-1 Uncertainty budget table Uncertainty Probability value distribution 不確かさ値 確率分布 0.001 mm 0.1 μm +2x10-6 /°º℃ ±0.5 °℃ Rectangular 一樣分布 Normal 正規分布 Rectangular 一樣分布 Rectangular 一樣分布 Combined uncertainty uc 合成不確かさ Divisor 除数 √12 2 √3 √3 Expanded uncertainty Uc (k=2, 95% confidence) 拡張不確かさ Standard Sensitivity uncertainty coefficient |cx|ul 標準不確かさ 感度係数 u (x₁) um C₁ 0.333 μm 0.289 μπ 0.050 μm 1.154x10-6 /°℃ 0.289 C 1 1 -1 - 12.5004 mm'℃ -0.00028 mm/℃ 0.333 0.289 0.050 0.014 0.081 0.451 um 0.90 μm 304 Build up the uncertainty budget table The calculation results and procedure are summarized as the uncertainty budget table shown in Table 3-1. 3-1) Calculate how much you can reduce the measurement uncertainty by increasing the number of replicated measurements to 16 based on the same standard deviation in Section 3.3.

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