G D & T and Co-ordinate Metrology

G D & T and Co-ordinate MetrologyPresented by: Mr. Nilay Thakore ( Sr.Ex) Unit 5, GCEDAD Dept.Email: nilaythakore@idmc.coopExt: 338Mobile: 9586281878

IndexIntroduction metrologyMethods of measurementsUncertainty SourcesSWIPE ConceptWhy use G D & T ?G D & T SymbolsFirst principle: examplesAdvance Metrological InstrumentsCMM concept,construction,types,applications

1. Introduction metrology

The science/study of measurement is called metrology. Generally a measurement is in two parts, a number and a unit.eg how long is it? 2 meters.A measurement tells us about the property of something.A measurement is always made using some instrument.What is not a measurement? Counting, comparing two string which is longer and test/experiment which leads to yes/no or pass/fail result.

Sr. no.Physical quantityName of the unitSymbol1LengthMeterm2TimeSecondS3MassKilogramKg4TemperatureKelvinK5Elec. CurrentAmpereA6Luminous intensityCandelaCd7Quantity of SubstanceMolemol

when the need is defined & justified, weather we have it or not, we have to pay the price of both the conditions.

2. Methods of measurements

Measuring Instruments Classification:

3. Uncertainty SourcesLong term ReproducibilityThermal expansion Thermal gradient and coefficient of thermal expansion.Elastic deformation Probe contact deformation, compression of the artifact under their own weight.Scale calibration Uncertainty of artifact standard, linearity, scale thermal expansion.Instrument Geometry Abbe offset, cosine errors, obliquity etc.Artifact effects Flatness, Parallelism, Roundness etc.

4. SWIPE ConceptThe 5 basic elements which define the accuracy of a measuring system are:

5.Why use G D & T ?

Allows max. Production ToleranceGuarantees fits and interchangeability of mating parts and assembliesReduces potential for error in interpolation.

6. G D & T Symbols

DatumA datum is a theoretically exact point, axis or plane from which the location or geometric characteristics of a part feature are established.

MMC & LMCWhen a part feature contains the maximum amount of material allowed within the specified size limit, it is said to be in its max. material condition.- The MMC of an external feature is its upper size limit.- The MMC of an internal feature is its lower size limit. When a part feature contains the least amount of material allowed within the specified size limits it is said to be in its least material condition.The LMC of an external feature is its lower size limit.The LMC of an internal feature is its upper size limit.

FlatnessA Flatness tolerance zone is the distance between two parallel planes, the part surface must lie between them.

StraightnessA straightness tolerance is used to control the straightness of a surface or axis. It specifies how much the surface or axis is allowed to vary from the perfect straight line implied by the point.

Circularity Circularity refers to the roundness of a cylindrical ,cone shaped or spherical part feature at any given cross-section.

A circularity tolerance specifies how much the cross-section is allowed to vary from the perfect circularity implied by the point.

A circularity tolerance zone is bounded by two concentric circles. The surface of the cross-section must lie between them.

Cylindericity

Cylindericity refers to the roundness of pins, shaft and other cylindrical features along their entire length.

A Cylindericity tolerance specifies how much the surface of the cylindrical feature is allowed to vary from the perfect cylinder implied by the drawing.

A Cylindericity tolerance zone is bounded by two concentric cylinders as specified distance apart The surface of the cylindrical feature must lie between them.

PerpendicularityPerpendicularity refers to a part surface, centre plane or axis that is 90 degree to a datum plane or axis.

AngularityAngularity refers to a part surface, centre plane or axis at specified angle other than 90 degree to a datum plane or axis.

ParallelismParallelism refers to:

A surface or center plane that is an equal distance at all points from a datum plane.An axis whose entire length is an equal distance from a datum plane or datum axis.

Profile TolerancesA Profile is a two dimensional outline of a part feature from top, side or front view. On a drawing, it is typically defined by basic dimensions in the form of sizes, radii, angles or arc.

There are two types of profile tolerances:

Profile of surfaceProfile of a line

Circular Run outA Circular run out tolerance controls the relationship of individual circular elements of the part feature to a datum axis.

Total Run outA total run out tolerance controls the relationship of the entire feature surface to a datum axis.

PositionPosition refers to the theoretically exact location of the centre, axis or centre plane of a feature in relation to another feature or datum.

A position tolerance specifies how much the centre, axis, or centre plane is allowed to vary from its theoretically exact location.

ConcentricityConcentricity describes the relationship between the axes of two or more cylindrical features. Perfect concentricity exists when the axes coincide.

SymmetryA part feature that can be divided into two equal halves is described as symmetrical.

7. First principle: examples

8. Advance Metrological Instruments

*Facility: Roundness Tester (RA-116)Roundness Tester (RA-116) Can Measure Critical Parameters asRoundnessCoaxialityConcentricityFlatnessCircular Runout (Radial and Axial)Perpendicularity (Plane and Axis)ThicknessDeviationParallelismRotational and Axial Accuracy of 0.04 MicronsMaxm Probing Dia 280mmMaxm Work piece Dia 440 mmTable Loading Capacity 25 KgProbing Height 280mmProbing Depth 100mm Latest Software enables availability of Latest Calculation Methods, Filters for Measurement, Different UPR Settings

*Roundness Tester Applications

*Facility: Surface Roughness Tester (SJ201)Surface Roughness Tester (SJ201)Can Measure Critical Parameters asRa, Ry, Rz, Rt, Rp, Rq, Rv, Sm, S, Pc, R3Z, Mr(C) Rpk, Rvk, Rk, Mr1, Mr2, A1, A2, Vo, Rz1max etc Equipped with Universal Standards, Filters, Profiles, Cut Off Values, Speed etcEasy to Carry and Handle; Can be kept directly on Job alsoCan be easily mounted on Height Gauge or even Magnetic StandDifferent Detectors can measure Roughness of jobs with Small Holes, Grooves, Collars etc

Applications

*Facility: Laser Scan Micrometer (LSM 503)Laser Scan Micrometer (LSM 503) Fast and Accurate Machine used for Diametrical and External MeasurementHigh Accuracy of up to 0.6 micronsMeasurement range of 0.3 to 30mmResolution of 0.00002mmRepeatability of 0.11 MicronsCan take 3200 Scans Per Second

*Facility: Micro hardness Tester (HM112)Micro hardness Tester (HM112)Different Ranges of Loads available as10, 25, 50, 100, 200, 300, 500, 1000 GramsObjective lens of 50X and Occular Lens of 10X provide 500X of large magnification Digital X-Y Table enables measurement of Case Depth

*Facility: Micro hardness Tester (HM112)Applications

*Facility: Optical Profile Projector (PJA-3005)Optical Profile Projector (PJ-A3005)Magnifies small jobs for Inspection at small Edges, CornersAngular Measurement of complete 3600 Up gradation to Software like MCOSMOS2D OR QM Data 200 can enable measurements ofRadiusCenter to Centre DistancesPerforming AlignmentsRelations between Parameters

*Facility: Measuring Microscope (MF-1010)Measuring Microscope (MF-1010)

Extended Version of Profile Projector Can measure Linear DimensionsUp gradation to Software like MCOSMOS2D OR QM Data 200 can enable measurements ofRadiusCenter to Centre DistancesPerforming AlignmentsRelations between Parameters

9. CMM
Co-ordinate measuring machines.

Types of CMM

Fixed CMM: a.) Bridge type

b) Gantry Type Accuracy Range:2.5+3L/1000 to 10+10L/1000

Accuracy Range: 0.3+L/1000 to 5+L/200

c) Horizontal Arm

Accuracy range:15+L/100 onwards

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Trigger and High Accuracy Scanning sensorsLSP-X3 Max. Stylus extension360 mmLSP-X5 Max. Stylus extension500 mmLSP S2/S4 Max. Stylus extension from600 to 800 mmLSP-X1 Max. Stylus extension220 mmTesastar Manual SwivellingTesastar I Manual IndexableTesastar-mMotorized IndexableLeica T-ProbeWalk around measuring probeTesastar-mpMagnetic tip modulesStationaryPortableMicro

Geometries andApplicationsAs a consequence of that, depending on the type of geometry:

different Software are needed different Sensors are needed different Machine Structures are needed

Simple GeometryComplex GeometrySculptured Geometry

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Software for all requirementsPC-DMIS, General purpose & for sculptured Geometries

Quindos Prismatic & Special geometriesChorus CADPC-DMISQUINDOSCogniTensCogniTens software package for white light measurement, sheet metal inspection, assembly analysis and reverse engineeringChorusCAD, /SurferSheet metal StationaryPortableMicro

Thank You

Details of GD & T resources at z:(trashcan)/GDNT

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