文档介绍：LESSON THREE SURFACE QUALITY
Surface quality is another aspect of machining accuracy. It consists of the surface finish and the physic-mechanical state of the surface layer. It affects the proper functioning and service life of the parts.
Surface Finish
Machining accuracy is expressed quantitatively in machining error. Surface finish is expressed quantitatively in surface roughness. The surface roughness on a machined workpiece surface is caused primarily by the geometrical factors (cutting tool geometry and cutting feed), the plastic deformation of the surface material, as well as the vibration of the MFTW system during machining.
几何形状
The surface roughness of a workpiece after machining depends upon many technological factors, such as the workpiece material, tool material, tool geometry, cutting conditions (cutting speed and feed), rigidity of the MFTW system, cooling condition in machining process, and so on. The surface roughness is a kind of micro geometrical deviation or micro-irregularity of workpiece surfaces. It appears on all machined workpiece surfaces no matter how smooth they look to the naked eye. In regard to the criteria for evaluating surface roughness, refer to other textbooks, ISO, and other standards and references.
The surface roughness of machined parts influences their performance to a great extent. In order to ensure product quality, to improve its service life, and to reduce its production cost, the surface roughness of machine parts has to be specified accurately in design and carefully controlled in manufacturing.
不规则性,不平度
criterion
ISO:International anization
Physic-Mechanical State of Surface Layer
In machining process, the metal nearest the workpiece surface deforms plastically. This is due to the intrusion of the cutting tool rake to the workpiece surface material, the friction between the tool relief and the machined surface, and the effect of the tool nose radius. This results in the surface layer on the workpiece in quite