Engineering Metrology and Instrumentation

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Jacob Kennedy
5 years ago
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in contaminant removal Chemical Cleaning Solution

1 3 types Mechanical Cleaning Physically disturb contaminants Electrolytic Cleaning Abrasive bubbles aid in contaminant removal Chemical Cleaning Solution Saponification Emulsification Dispersion Aggregation Cleaning of Surfaces

2 Engineering Metrology and Instrumentation Metrology refers to the measurement of any type of dimensions (length, thickness, diameter, angle, etc.) Focus on Dimensional Tolerance (functionality, interchangeability, cost)

3 Describing Quality of Instruments Resolution- the smallest difference in dimensions that an instrument can detect. Precision- the instruments ability to give repeated measurements (thermal expansion affects precision, standard measuring temperature is 20 0 C). Accuracy- The ability of a measurement to match the actual value of the quantity being measured.

4 Types of Measurement and Instruments Used

5 Types of Measurement and Instruments Used

6 Common Analog Instruments A caliper gage with a vernier A vernier

7 The Micrometer (a) (c) Analog Micrometer Digital Micrometer

8 Angle-Measuring Instruments Bevel Protractor Vernier for angular measurement

9 Angle-Measuring Instruments Sine Bar Gage blocks are added until the top surface is parallel to the surface plate. The angle is calculated using trig. relationships.

10 Comparative Length Measurement Multiple-Dimension Gaging

11 Electronic Gages Measuring Bore Diameters Vertical Length Mesauring Instrument

12 Laser Scan Micrometer

13 Straightness Measurement

14 Interferometry for Measuring Flatness Optical Flat is a glass disk or fused-quartz disk with parallel flat surfaces. A light beam with one wavelength is aimed at the surface at an angle and splits into two beams. The number of fringes relates the distance between part and flat.

15 Interferometry for Measuring Shaped or Textured Surfaces Fringes on a surface with two inclinations, the greater the incline, the closer the fringes. Curved fringe patterns indicate curvatures on the workpiece surface Fringe pattern indicating a scratch on the surface.

16 Measuring Roundness Measuring roundness using V-block and dial indicator

17 Measuring Roundness Part supported on centers and rotated Circular tracing, with part being rotated on a vertical axis

18 Measuring Profiles Radius Gages Dial Indicators

19 Measuring Profiles Gear-Tooth Caliper Gear-Tooth Micrometer

20 Horizontal-Beam Contour Projector Image is projected on screen at magnification of 100X or higher. Measurements made directly on screen.

21 Gages Plug gages for holes Ring gages for round rods GO means smaller than desired size and should fit perfectly, if NOT GO gage also fits then tolerance is not met.

22 Gages Snap Gage with adjustable anvils

23 Gages Pneumatic Gage

24 Modern Measuring Instruments Electronic gauges and Laser Machines Micrometers Laser Interferometry Photoelectric digital length measurement Coordinate-measuring machines (CMM)

25 Electronic Gauges Determine travel length by changes in electrical resistance, inductance, or capacitance. A commonly used E-Gauge is the linear-variable differential transformer (LVDT) Generally use a very accurate specified probe tip.

26 Laser Micrometers A laser beam scans a workpiece, generally at a rate of 350 times per second. Generally capable of resolutionsas high as µm (5 µin).

27 Laser Interferometry Used primarily to check and calibrate machine tools. Also are used to compensate for positioning errors in CMM and CNC machines

28 Photoelectric Digital Length Measurement Measures basic dimensions of general 3D parts. Resolution ranges from µm.

29 Coordinate-Measuring Machines (CMM) Very versatile and capable of measuring complex profiles with resolution of 0.25 µm; 10µin at high speeds. Larger machines can be expensive although most of the touch probe machines for small shops cost around $20k

30 More CMM s

31 References

BHARATHIDASAN ENGINEERING COLLEGE, NATTRAMPALLI. DEPARTMENT OF MECHANICAL ENGINEERING FAQ

BHARATHIDASAN ENGINEERING COLLEGE, NATTRAMPALLI. DEPARTMENT OF MECHANICAL ENGINEERING FAQ Year/Sem : III/V Sub.Code/Title: ME6504- METROLOGY & MEASUREMENTS UNIT-I CONCEPT OF MEASUREMENT PART-A 1. Define