UNIT-2 Linear and Angular measurements in metrology

PPT

1. ME6504 METROLOGY AND MEASUREMENTS UNIT-2 LINEAR AND ANGULAR MEASUREMENTS

2. LINEAR MEASUREING INSTRUMENTS VERNIER INSTRUMENTS MICROMETER SLIP GAUGES COMPARATOR

3. VERNIER INSTRUMENTS External Vernier Caliper Internal Vernier Caliper Both Measuring and Marking Vernier Height Gauge Master Dial Indicator Vernier Caliper Vernier Depth Gauge Combination of Depth and Angle Digital Length Gauge Master Height Gauge

4. MICROMETER Outside micrometer- to measure external dimensions Inside micrometer- to measure internal dimensions Stick micrometer Micrometer depth gauge Thread micrometer V-anvil micrometer caliper

5. Blade type micrometer Micrometer for measuring thickness of cylindrical walls Dial micrometer caliper Bench micrometer Taper screw operated internal micrometer Groove micrometer Digital micrometer Differential micrometer

6. STICK MICROMETER This micrometer is used to measure longer lengths is known as stick micrometer. Actually, these micrometers are formed by connecting 150mm or 300mm. Accuracy is +or- 0.005mm through out the measurement.

7. Stick Micrometer

8. Micrometer Depth Gauge It is used to measure depth of holes, slots and recesses. The maximum range of depth micrometer is 0-225mm.

9. Thread Micrometer It is used to measure threads with in certain range of thread pitches. A small error can arise because of anvil settings. To measure pitch diameter.

10. V-anvil Micrometer Caliper True running error can be checked quickly by V-anvil micrometer caliper in grinding and other special machine. Error due to incorrect handling.

11. Blade Type Micrometer It is best suited for measuring circular formed tools, diameter of narrow grooves, slots, keyways.

12. Micrometer For Measuring Thickness of Cylindrical Walls

13. Dial Micrometer Caliper

14. Bench Micrometer

15. Taper Screw Operated Internal Micrometer

16. Groove Micrometer It is specially designed for grooves, recess and shoulders which are located centrally

17. Digital Micrometer

18. Differential Screw Micrometer The theoretical value of accuracy is 0.0002mm It has two pitches of 1.25mm and 1.00mm. The thimble is graduated into 100 divisions. Very high degree of accuracy in measurement

19. Comparator Comparators are the instruments calibrated by means of end standards to measure unknown dimensions. The purpose of a comparator is to detect and display the small differences between the unknown linear dimensions and the length of the standard . comparators are of following types (a)Mechanical comparators, (b) Optical Comparators. ( c) Pneumatic comparators, (d) Electrical comparators

20. Mechanical Comparators

21. A spindle attached to the movable member is in contact with the component to be measured. Movable member moves through a distance x , in response to displacement with respect to fixed member. There is no friction and the hysteresis effect is minimized by using suitable steel for the reeds.

22. MECHANISM OF DIAL INDICATOR

23. Optical Comparators Optical comparators are based on the principle of projection of image. A simple optical comparator for measurement of linear dimension is shown in Figure

24. The actual difference x between the two dimensions is amplified by a lever to give an angular displacement  of a pivoted mirror. The reflected ray is deflected through an angle 2  from the original line and gives a reading of X on the scale. The main advantage of an optical comparator is that it is capable of giving higher degree of magnification due to reduction of moving members and better wear resistance qualities.

25. OPTICAL COMPARATOR

26. Pneumatic Comparators It works on the principle of pressure difference generated by the air flow. It has two orifices O 1 and O 2 with diameter d 1 and d 2 respectively. Through O 1 , air is supplied at a constant pressure , P s , which is the pressure of the source.

27. The area of orifice O 1 = A 1 = ( π / 4 ) . This area is fixed. The area of the second orifice through which air can pass O 2 = A 2 = π d 2 x . Thus, the area of orifice O 2 is variable and depends upon the displacement of the work piece x . The job is rotated along the jet axis.

28. SOLEX AIR GAUGE

29. Electrical comparator Electrical comparators are used as a means of detecting and amplifying small movements of a work contacting elements. It may use any of the following transducers for magnification. They are (a) strain gauges, (b) variable inductance transducers, and (c) variable capacitance transducers .

30. e.g. Checking or comparison of workshop slip gauges against inspection slip gauges . The second application is used to indicate with a green light if a dimension is within the limits . A red lamp indicates an undersize dimension; a yellow lamp indicates an oversize dimension.

31. LIMIT GAUGES A limit gauges is not a measuring gauge. It is used for inspecting purpose only. Purpose of using limit gauge Component are manufactured as per specified tolerance limits, upper limit or lower limit. The size of the component is with in the prescribed limits or not. For this purpose, we can make use of gauges known as limit gauges.

32. Types of limit gauges Plug gauges Ring gauges Snap gauges Plug gauges

33. Plug gauge One end is the GO end and the other end is NOGO end. Usually, the GO end will be equal to lower limit size of the hole and the NOGO end will be equal to the upper limit size of the hole. Double ended plug gauge

34. TAPER PLUG GAUGE It is used to check tapered holes. During the checking w ork, NOGO line remains outside the hole and GO line remains inside the hole. There are various types of taper plug gauges available such as Taper plug gauge-plain Taper plug gauge-tanged Taper ring gauge-plain Taper ring gauge-tanged

35. Taper plug gauge-plain Taper plug gauge- tanged

36. Taper ring gauge

37. Ring gauge

38. Snap gauge Double ended snap gauge Progressive snap gauge Adjustable snap gauge Plate type double ended snap gauge Plate type single ended snap gauge

39. Double ended snap gauge