Machinery's Handbook, 31st Edition
814 Surface Texture point of cutting, and the mechanical properties of the piece being ground. A small change
in any of the above factors can have a marked effect on the surface produced. Table 1. Surface Roughness Produced by Common Production Methods Roughness Average, Ra - Micrometers μm (Microinches μin) Process 50 (2000) 25 (1000) 12.5 (500) 6.3 (250) 3.2 (125) 1.6 (63) 0.80 (32) 0.40 (16) 0.20 (8) 0.10 (4) 0.05 (2) 0.025 (1)
0.012 (0.5)
Flame Cutting Snagging Sawing Planing, Shaping Drilling Chemical Milling Elect. Discharge Mach. Milling Broaching Reaming Electron Beam Laser Electro-Chemical Boring, Turning Barrel Finishing Electrolytic Grinding Roller Burnishing Grinding Honing Electro-Polish Polishing Lapping Superfinishing Sand Casting Hot Rolling Forging
Perm. Mold Casting Investment Casting Extruding Cold Rolling, Drawing Die Casting The ranges shown above are typical of the processes listed. Higher or lower values may be obtained under special conditions.
KEY
Average Application
Less Frequent Application Instrumentation for Surface Texture Measurement.— Instrumentation used for mea surement of surface texture, including roughness and waviness generally falls into six types. These include: Type I, Profiling Contact Skidless Instruments: Used for very smooth to very rough sur faces. Used for roughness and may measure waviness. Can generate filtered or unfiltered profiles and may have a selection of filters and parameters for data analysis. Examples include: 1) skidless stylus-type with LVDT (linear variable differential transformer) vertical transducers; 2) skidless-type using an interferometric transducer; 3) skidless stylus-type using capacitance transducer. Type II, Profiling Non-contact Instruments: Capable of full profiling or topographical analysis. Non-contact operation may be advantageous for softness but may vary with sample type and reflectivity. Can generate filtered or unfiltered profiles but may have diffi culty with steeply inclined surfaces. Examples include: 1) interferometric microscope; 2) optical focus sending; 3) Nomarski differential profiling; 4) laser triangulation; 5) scanning electron microscope (SEM) stereoscopy; 6) confocal optical microscope. Type III, Scanned Probe Microscope: Features high spatial resolution (at or near the atomic scale) but area of measurement may be limited. Examples include: 1) scanning tunneling microscope (STM) and 2) atomic force microscope (AFM).
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