Surface finish
The surface quality is an expression for the roughness in the surface inspection , usually in connection with a manufacturing process or a surface refinement . Common details of the roughness depth are:
- Average roughness value (arithmetic mean of the deviations from the center line) in μm
- Average roughness depth (mean value from the measured roughness depths) in μm
Such parameters are measured with a stylus device (special designs are called perthometers , for example ).
Influences on the surface roughness during machining are:
- Machining properties of the material
- Cutting material and wear condition
- Cutting geometry : cutting edge radius
- Cutting values : feed rate, cutting speed
- Cooling lubrication
- Machine rigidity and elasticity of tool, clamping device and workpiece
- Form deviations on guides and tools
Achievable mean roughness values R a
The achievable mean roughness values in μm of various manufacturing processes with particular care ( values in brackets are average values with normal care. These guide values may vary from case to case).
- Casting in sand mold: 12.5 (25)
- Casting in mold : 3.0 (12.5)
- Casting ( die casting ): 0.8 (6.3)
- Sintering (6–12)
- Turning (longitudinal): 0.2 (3.2)
- Turning (face): 0.4 (6.3)
- Planing, slotting : 0.2 (6.3)
- Files : 0.4 (3.2)
- Drilling : 1.6 (12.5)
- Grating : 0.2 (0.8)
- Scraping : 0.2 (3.2)
- Milling : 0.6 (3.2)
- Grinding : 0.012 (0.4)
- Honing , lapping : 0.006 (0.1)
Older names and visual recognition of the roughness depth
| designation | R a (µm) | feature |
|---|---|---|
| roughed | 3.2 to 25 | Grooves palpable and visible to the eye |
| settled | 1.6 to 3.2 | Scoring still visible to the eye |
| finely finished | 0.8 to 1.6 | Scoring no longer visible to the eye |
Individual evidence
- ↑ Susanna Labisch, Christian Weber: Technical drawing: Learn independently and practice effectively . Springer, 2013, ISBN 3-8348-9892-9 , pp. 119 ( limited preview in Google Book search).
- ↑ N. Zwanzer: Lecture Construction 4. Fundamentals of Technical Drawing. P. 10 , accessed on October 3, 2015 .