Surface Finish and Texture Notes

Manufacturing Processes and Surface Finish

• Surface finish specifications are more critical in processes like wooden parts for cabinetry.

Surface Texture Standards

• There are two standards for surface texture: one for terms and definitions, and another for specifying symbols on prints.

Surface Texture Symbol

• The current standard surface texture symbol resembles a "V".

Surface Characteristics

• A flaw is an unintentional interruption (crack or pit) not covered by the surface texture symbol.

Waviness vs. Roughness

• Waviness relates to wider surface distances, while roughness deals with immediate ups and downs.

Roughness/Smoothness and Manufacturing Processes

• Extremely smooth: Extra-fine honing and lapping.
• Good machine: Sharp tools, high speeds, extra-fine feeds and cuts.
• Very rough: Saw and torch cutting, forging, or sand casting.
• Coarse: Coarse surface grind, rapid feeds in turning and milling.

Precision of Surface Roughness

• Surface roughness precision is measured in micrometers or microinches, where "micro" means "one-millionth".

Measuring Surface Texture

• A profilometer is used to measure surface texture in microinches.

Surface Texture Symbol Specifications

• Specifies the minimum amount of material to be removed and the final roughness: Figure A
• Specifies the particular method to achieve the specified roughness value: Figure E
• Specifies that any production method can be used: Figure B
• Specifies that material must be removed, but no amount stated: Figure C
• Specifies no material can be removed: Figure D

Surface Texture Symbol Information

• The type of inspection machine to be used is NOT specified within the surface texture symbol environment.

Lay

• "Lay" describes the direction of the predominant surface pattern from the machining process.