 Metrology is science considering measurement

 Categories: › Scientific – deals with organization and development of etalons and their conservation(highest level) › Industrial – deals with function of measuring devices used in industry in manufacturing and testing processes › Legal – deals with precision of measurement in situations where the exact measurement is necessary for justice of economic transactions, health and security  Fields of metrology: › Weight › Electricity › Length › Time and frequency › Thermometry › Ion radiation and radioactivity › Volume › Acoustic measurements › Etc. Continuity  Is property of measured value or etalon value that can express the relation to reference on national or international level. This relationship is expressed through an uninterupted chain of relationships between components where the unceratainity is known. Unit definition International etalons Etalons are changing with development of science National etalons • Home national etalons Length etalon - meter • Foreign national etalons 1795 – bar made of brass 1799 – bar made of platinum and iridium 1960 - 1 650 763,73 times the wave length of Reference etalones radiation that is equal to transition of electron from quantum level 2p10 to level 5d5 in Cryptonium-86 1983 – distance reached by light in time of Company etalones 1/299 792 458 second.

Measurement Basic procedure for securing the continuity of measurement is the calibration. Calibration is aquiring metrological characteristics of measuring device. This is made by referencing them to etalones.

Reasons for calibration: 1) To secure that the value measured by the device is same as to another device or method 2) To secure the measured value is correct 3) To secure the reliability of measuring device.  Direct › measuring device measures directly the wanted quantity or property  Indirect › measuring device measures another quantity or property from that the wanted quantity or property can be calculated or derived  Absolute › I acquire directly a value of quantity or property  Comparatory › I acquire the difference between the etalon and the measured value only  caliper   block gauges  pasameter  microskope  lengthmeter  laserinterferometer  …  CMM (Coordinate measuring machine)  basic comunal device - calliper  precision: › 0,1; 0,05; 0,02 mm (nonius, ) › 0,01 mm (digital)  range… 150 ÷ 3000 mm  types: › classical(nonius) › digital › with indicator with nonius (Vernier sc.)  outer dimension  inner dimension  depth digital solar powered presentation:  display  display + output (RS232, USB)

IP66 – waterproof cover indicator The most common device: caliper  precision: › 0,01; 0,005 (mechanical) › 0,005 ÷ 0,0001 (digital)  range… (0 ÷ 25) ÷ (900 ÷ 1000) mm  types: › mechanical › digital measurement  outer dim.  inner dim.  depth special types:  plate  tubes  prizmatic  … special types:  plate  tubes  prizmatic  tolerances  thread  threetouch holemicrometer  … micrometer 0 30 0 30

2,24 20 2,76 20

0 0 0 0 2,51 2,49 www.somex.cz indicator gauge  not absolute measurement  must watch the „hand“ to see if it did not run the full circle  scale division!!! indicator gauge examples  accuracy (4 grades): › 0,5 ÷ 0,05 mm (cca 5 mm) › 8 ÷ 4 mm (cca 1 m)  range … ~ 0,1 ÷ 1000 mm  types: › steel (~ 800 HV) › sintered carbide › ceramic (~ 1350 HV) properties:  ground, polished, lapped  no surface protection  thin oil film

 geometric precision Ú12 134 –  primary block accuracy Sem inář z (0,02+0,05 .L [m]) mm Tec hnol ogie II. – 2. cvič 24 10.10.2017 ení dimenstions  a set of different dimensions in a box (ex. 32 pcs set)  1,005 mm (1pc)  1,01-1,09 step 0,01 mm (9pcs)  1,1-1,9 mm step 0,1 mm (9pcs)  1-9 mm step 1 mm (9pcs)  10-30 mm step 10 mm (3pcs)  50 mm (1pc)  for specific value = put together parts › Handle with care!!!

 Together with a two-axis table with micrometric screws it is a universal measuring device  The ocular includes the „crosshair“ › Two perpendicular lines › Three lines rotated 60° › Four line rotated 45° › Shape lines (thread profiles)

Universal Length Measuring Machine  Accuracy – 1 ÷ 0,1 mm  Measuring range – up to 6 meters Laserinterferometer  Accuracy = up to 0,01 mm (depending on measured length) (0,5+1,1.L/1000 ) mm  Range: very variable (up to 100 meters)  Angle gauges  – for right angle   Sine bar  level  Like linear block gauges  For fast measurements in practical life  Mainly 90°  Also 45°, 60°, 120°a 135°  Rotary arm  digital  With moving arm  Rotary arm  digital  With moving arm  With occular  inclinometer Used with block gauges  Mechanical – hydraulic  Gyroscopic -  Digital - accelerometer  threepin method  gauges  thread snap gauge  microscope  Micrometer

Problem is that the thread si too complex to be measured. And also that the diameters are not recognizable on the part Nominal diameter (Major and minor diameter) Indirect measurement – we measure the „Diameter over pins“ and we can calculate from it the nominal diameter

 For pitch measurement  Gauge is placed to the thread  Thread snap gauge  Thread plug gauge

List of tasks:

1. Profile projector measurements (-o-) 2. Cylindrical plug gauge control on microindicator (-o-) 3. Cone measurement on a laboratory microscope 4. Angle measurement with an optical bevel 5. Frontal run-out measurement (-o-) 6. Run-out measurement of a rotary part (-o-) 7. Thread measurement using a three wire method 8. Measurement using a laboratory microscope (-o-) 9. Gear measurement 10. Machine operational accuracy – PC evaluated 11. Run-out measurement of a spindle 12. Batch measurement of cylindrical parts Task: Measure the spacing R (distance between center points) of clamping holes in the spring plate. Use the profile projector for the measurement.

 Measure and write down the coordinates of tangents of measured holes!

Attention! – micrometrix thread has two revolutions per milimeter  Ring scale division is 50 scales.

 Carefully read if you see the „half-milimeter line“ on the main scale + add the value from the ring. Center Diameter Diameter Hole Coordinate Spacing coordinate value in axis value X1.1 X1.2 1 Y1.1 Y1.2 … … … … Problem: Decide about the applicability of the GO and NOT GO ends (good and bad ends) of a workshop cylindrical plug gauge for hole diameter control. Use the microindicator for measuring.  Deviation with a block gauge (40 mm) = -35  Deviation with a measured part = 12

 Total deviation = 12-(-35) = 47  Scale = 0,001 mm  Dimension of deviation = 47 scales = 0,047 mm  Dimension of measured part = 40 + 0,047 = 40,047 mm

!!! Results discussion !!! Problem:  Measure the frontal run out of a universal clamping head used for workpieces clamping in both open and closed state.  Write down the values and express them by using a column chart. (measured values in columns, separate columns for different places of measurement). Position [mm] clamp 1 2 3 4 Check no.1 Open -0,02 -0,01 0,01 -0,01 -0,02 Closed -0,04 -0,03 0,02 0,01 -0,04

0.03 0.02 0.01 0 clamp 1 2 3 4 open -0.01 closed -0.02 -0.03 -0.04 -0.05 0.03 0.02 0.01 MAX 0 clamp 1 clamp 2 clamp3 clamp 4 -0.01 -0.02 MIN -0.03 -0.04 open -0.05 closed

Runout = maximum value

ex. RUNOUT OF OPEN CLAMP = MAX-MIN Problem: Measure the radial and axial run-out of rotary (spindle) part

Express the results with a polar chart and mark the maximum run- out value in this chart.

deviations for axial runout [mm] 0.28 0.26 0.24 0.22 Problem:

Measure the nominal thread diameter d2 and the lead (pitch) of a metrical thread on given part. Compare the measured values with nominal values in table. Discuss the results.

Thread cross hair

2 1

movement of crosshair d2

3