Quick Guide to Precision Measuring Instruments

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PG52ColumnStylusFixtureBaseDrive unitMeasuring loopProbe (pickup)WorkpieceISO 4287: 1997 Geometrical Product Specications (GPS) –Surface Texture: Prole method– Terms, denitions, and surface texture parametersISO 11562: 1996 Geometrical Product Specications (GPS) –Surface Texture: Prole method– Metrological characteristics of phase-correct ltersISO 4288: 1996 Geometrical Product Specications (GPS) –Surface Texture: Prole method– Rules and procedures for the assessment of surface textureISO 3274: 1996 Geometrical Product Specications (GPS) –Surface Texture: Prole method– Nominal characteristics of contact (stylus) instrumentsNominal radius ofcurvature of stylus tip:µmStatic measuring force atthe mean position ofstylus: mNTolerance on staticmeasuring forcevariations: mN/µm20.750.03550.75 (4.0) Note 10.210Note 1: The maximum value of static measuring force at the average position of a stylus is to be 4.0mN for a special structured probe including a replaceable stylus.λc mmλs µmλc/ λs Maximum rtipµmMaximum sampling length µm0.082.53020.50.252.510020.50.82.53002 Note 10.52.583005 Note 21.582530010 Note 25Note 1: For a surface with Ra>0.5µm or Rz>3µm, a significant error will not usually occur in a measurement even if rtip = 5µm.Note 2: If a cutoff value ls is 2.5µm or 8µm, attenuation of the signal due to the mechanical filtering effect of a stylus with the recommended tip radius appears outside the roughness profile pass band. Therefore, a small error in stylus tip radius or shape does not affect parameter values calculated from measurements. If a specific cutoff ratio is required, the ratio must be defined.Relationship between Cutoff Value and Stylus Tip RadiusThe following table lists the relationship between the roughness prole cutoff value lc, stylus tip radius rtip, and cutoff ratio lc/ls.Nominal Characteristics of Contact (Stylus) Instruments60°R2 µm60°R10 µm90°R5 µm60°R5 µm90°R2 µm90°R10 µmTracedproleStylus tipSurfaceProbeMeasure-mentloopExternaldisturbancesReferenceguide skidFeeddeviceDrive UnitReferenceproleZ-axis Signal Transfer UnitTransducerAmplierADconverterInput/OutputTotalproleNominalformremovalProle lter λSInput/OutputPrimaryproleAnalysis according to ISO 4287Nominal Characteristics of Contact (Stylus) InstrumentsStylus ShapeStatic Measuring Force (JISB0651)A typical shape for a stylus end is conical with a spherical tip.Tip radius: rtip = 2 µm, 5 µm or 10 µmCone angle: 60°, 90°In typical surface roughness testers, the taper angle of the stylus end is 60˚ unless otherwise specied.Surftest (Surface Roughness Testers)