SURFACE TEXTURE The characteristics quality of an actual surface due to small departures from its general geometrical form which occurring at regular or irregular intervals tend to form a pattern or texture on the surface ID: 138609
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MEASUREMENT OF SURFACE FINISH
SURFACE TEXTURE:“ The characteristics quality of an actual surface due to small departures from its general geometrical form which, occurring at regular or irregular intervals, tend to form a pattern or texture on the surface”
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1. SURFACE TEXTURE
“The General form” relates to the dominant shape of surface which it is intended to reproduce, & constitute a first approximation to the design formIt is possible for two or more kind of irregularity to be combined in the complete texture of a surface in such a way that they are not readily distinguishable individually by eye or touch
Surface texture varies according to the machining processes used in producing it (eg. Metal machining)
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1. SURFACE TEXTURE
Difference in surface texture are apparent by visual examination & can be felt readily by passing a finger nail over the surfaceThe texture of surfaces can be regular or non-regular in characterFACTORS PRODUCING SURFACE IRREGULARITY:Faulty toolsInherent imperfections in the m/c tools
Errors due to personal element
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2. METHODS OF MEASURING S. FINISH
SURFACE INSPECTION BY COMPARISON MEHODS: these include:Touch inspection
Visual inspectionScratch inspection
Microscopic inspectioon
Surface photographs
Micro
interferromter
Wallace surface dynamometer
Reflected light intensity
Comparison by standard specimens
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2. METHODS OF MEASURING S. FINISH
Direct Instrument MeasurementIntersection method Interference methodStylus method
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3. NUMERICAL EVALUATION OF SURFACE
TEXTUREPractice adopted for obtaining numerical evaluation of surface texture is to use a parameter based on the cross-sectional profile of the surface under examinationThere are two system for Numerical evaluation of surface finish, i.e
:Centre line average (CLA)
Root mean square (RMS) value of height undulations of the surfaceThe CLA system is more popular in UK, while the RMS is more popular in USA
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3. NUMERICAL EVALUATION OF SURFACE
TEXTUREFOR EQUATIONS of CLA & RMS, AS DEOMOSNTRATED ON BOARD
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4. TOMLINSON SURFACE FINISH
RECORDERAs Demonstrated for figure on next slide on board24/03/2012
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4. TOMLINSON SURFACE FINISH
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5. ADVERSE EFFECTS OF POOR SURFACE FINISH
Book: Engineering metrology & instrumentationPage#: 234DO YOUR SELF
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