Metrology & Measurement Lab ME-594 Contacts: Mail: poddar05@gmail.com Web: http://www.ajourneywithtime.weebly.com/ Lecture by: M K PODDAR Asst. Professor ME Department NSHM, Durgapur
Metrology & Measurement Lab ME-594, Credits: 1 At least 6 experiments to be conducted from the following : 1. Taking measurements using following instruments : (i) Vernier height & depth gauge, (ii) Dial micrometer, (iii) Thread gauge, (iv) Radius gauge, (v) Filler gauge, (vi) Slip gauge. 2. Measurement of angle of a component using : (i) Vernier bevel protractor, (ii) angle gauges, (iii) Sine-bar and slip gauges. 3. Checking / measuring parallelism, cylindricity and concentricity of components using dial indicator. 4. Measurement of a specific dimension for a lot of components, and prepare a histogram from the data obtained. 5. Measurement of surface finish by a Talysurf instrument. 6. Measurement of micro feature of a product (eg. Thread of a bolt or saw etc.) in a profile projector. 7. Determine natural cooling characteristics of a heated object by using a thermocouple. 8. Measurement of air velocity across an air duct using anemometer. 9. Fixing a strain gauge on a cantilevered flat section of steel. Then calibration of it as a force dynamometer using a Wheatstone bridge and loading arrangement. (NB.: This experiment has to be done over two days one day for fixing and second day for calibration).
Exp 04: Measurement of micro feature of a product (eg. Thread of a bolt or saw etc.) in a profile projector. Aim: To measure the thread parameters of a given screw thread by using profile projector
Aim: To measure the thread parameters of a given screw thread by using profile projector APPARATUS: Profile Projector THEORY: By using lenses and beams of light, profiles of small shapes can be magnified. The enlarged image can be compared with accurate magnified drawing made to the scale of magnification. Such a comparison can reveal any deviations in the sizes and contours of the objects and to get a numerical assessment of such deviations, measurements can be made on the enlarged shadow. The measured dimensions on the shadow will then have to be divided by the multiplication factor. The projection apparatus used for this purpose is termed as an optical profile projector. The essential features of a profile projector are that, it should be accurately as stated and that there should be maximum latitude in holding and adjusting the work piece and examining the projected shadow. Parameters to be measured: Major and minor diameter of screw Depth of screw Pitch of screw Thread angle
Procedure: Observation Table: Results & Conclusion: Fig. Elements of parallel screw threads
Major Diameter is that of an imaginary cylinder (termed the major cylinder) which just embraces the crests of an external thread or the roots of an internal thread. Minor Diameter is that of an imaginary cylinder (termed the minor cylinder) which just embraces the roots of an external thread or the crests of an internal thread. Depth of screw is the distance between the crest and root of the thread Pitch is the distance, measured parallel to the axis, between corresponding points on adjacent thread forms in the same axial plane and on the same side of the axis. Flank Angles (β, γ): The angles between the individual flanks (leading and trailing flank) and the perpendicular to the axis of the thread, measured in an axial plane section. Thread Angle (α): Sum of the two flank angles.
Observation Table: Maximum Diameter Sl No Initial Reading Final Reading Diff. MSR VSD VSR = VSD *LC Total MSR VSD VSR Total Minimum Diameter Sl No Initial Reading Final Reading Diff. MSR VSD VSR = VSD *LC Total MSR VSD VSR Total Depth of Screw Sl No Initial Reading Final Reading Diff. MSR VSD VSR = VSD *LC Total MSR VSD VSR Total
Pitch of the Screw Sr No Initial Reading Final Reading Diff. MSR VSD VSR = VSD *LC Total MSR VSD VSR Total Thread angle Sr no Initial β Final γ Total α = β + γ Degree minutes Degree minutes