Inspection and Measurement Inspection An action to insure what is being manufactured conforms to the specifications by attributes use of gages: go or no-go by variables use of calibrated instruments Measurement An act of measuring by variables, an fundamental activity of inspection Four fundamental measures length (L) time (T) mass (M) temperature (T) ME 363 2-1
Length Standard Gage blocks Grade Inches Millimeters Recalibration Period 0.5 (laboratory) 0.000,001 0.000 03 Annually 1 (laboratory 0.000,002 0.000 05 Annually 2 (precision) 0.000,004 +0.000 10 Monthly to semiannually 0.000,002 0.000 05 3 (working) 0.000,008 0.000 20 Monthly to quarterly 0.000,004 0.000 10 ANSI/ASME B89.1 ME 363 2-2
Geometric Dimensioning and Tolerancing Basic: Definition: A numerical value used to describe the theoretically exact size, profile, orientation, or location of a feature of datum target. It is the basis from which permissible variations are established by tolerances in feature control frames or on other dimensions or notes. Example: ME 363 2-3
ME 363 2-4
ME 363 2-5
Geometric Dimensioning and Tolerancing Datums: Definition: A theoretically exact point, axis, or plane derived from the true geometric counterpart of a specified datum feature. A datum is the origin from which the location or geometric characteristics of features of a part are established. ME 363 2-6
Accuracy and Preciseness ME 363 2-7
Tolerance Tolerance: Undesirable but permissible deviation from a desired dimension ME 363 2-8
Allowance and Tolerance Needed to specify fitting condition of two mating parts Allowance: Intentionally introduced to control the fit Clearance Interference ME 363 2-9
Fitting ME 363 2-10
Specifying Tolerance and Allowance Specifying tolerance Bilateral 2.000 0.002 Unilateral 2.000 0.004 0.000 Limit max. 2.002 min. 1.998 Clearances ANSI standard: 8 classes ISO standard: 18 grades ME 363 2-11
Tolerance and Allowance ME 363 2-12
Measurement by Vernier Calipers ME 363 2-13
Micrometer Caliper ME 363 2-14
Laser Interferometer ME 363 2-15
Vision System ME 363 2-16
Vision system: shape detection ME 363 2-17
Laser Triangular Sensor ME 363 2-18
Coordinate Measuring Machine(CMM) ME 363 2-19
Surface Roughness Measurement DEFINITIONS: Roughness Waviness Lay ME 363 2-20
Roughness Measurement R R a q n i1 y i n y y y 2 i n ME 363 2-21
Example Surface roughness measurements were taken from the surface and the measured values are shown in Table 1. Determine Ra. Avergage y(i) 0.9 1.1 1.55 1.2 0.5-0.91-1.6-1.4-1.3-1.9 0.00 abs(y(i)) 0.90 1.10 1.55 1.20 0.50 0.91 1.60 1.40 1.30 1.90 12.36 R a y i y n 0.9 1.11.55 1.2 0.5 0.911.6 1.4 1.31.9 10 12.36 1.24 10 ME 363 2-22
Roughness Notation ME 363 2-23
Statistical Process Control Frequency Distribution : variance = x 2 x i n 1 x x: mean x= 1 n R : range x x max min ME 363 2-24
Quality Control Chart X UCL LCL n i1 X X n i 3 3 i i1 R R X high X low UCL LCL R R n n X X X R R 3 R 3 R R X X ME 363 2-25
Process Capabilities C p USL LSL ' 6 ˆ ' ˆ : true standard deviation C pk ' min, USL X LSL X 3 ˆ ' ' ME 363 2-26
Thickness, 10-5in Example (Thickness of Disk Grinding) Cycle no. Output Target 1 3072 3070 2 3105 3070 3 3081 3070 Thickness Output 4 3066 3070 5 3069 3070 6 3074 3070 7 3072 3070 8 3068 3070 9 3074 3070 10 3069 3070 3120 3100 3080 3060 3040 Output Target LSL USL 11 3070 3070 12 3078 3070 3020 1 3 5 7 9 11 13 15 13 3072 3070 14 3059 3070 Cycle no. 15 3075 3070 ME 363 2-27
Example X ' 3073.6, 10.1, C pk ' min, min USL X LSL X 3 ˆ ' 3110 3073.6, 3030 3073.6 min 36.4,43.6 30.3 310.1 ' 1.2 ME 363 2-28
Output thickness (10-5 in) Intelligent Control Example Computer Hard Disk Grinding Process 3120 Upper limit Conventional Adaptive 3100 3080 3060 3040 3020 Target Lower limit 0 20 40 60 80 100 Cycle number ME 363 2-29