Physical factors physical factors are factors related to the properties of the processed material and the cutting mechanism.
In the cutting process, the obtuse angle caused by the wear of the cutting edge and the extrusion and friction of the back knife on the workpiece surface cause the plastic deformation of the metal layer on the machined surface, causing the distortion of the residual area, resulting in the increase of the surface roughness value.
When turning brittle materials, chipping chips are produced, resulting in uneven fracture cavities or chipping marks on the machined surface, leaving many pockmarks and increasing the surface roughness value.
The chip buildup produced in the cutting process is both irregular and unstable. On the one hand, its irregular hard points partially replace the cutting edge for cutting, leaving traces of different depths. On the other hand, a part of the fallen chip buildup of the machine tool is embedded in the machined surface, and the machine tool forms irregular burrs or hard points, which increases the surface roughness value.
When cutting at low speed, it is easy to produce scale thorns, that is, transverse cracks approximately perpendicular to the cutting speed are formed on the machined surface, and scale burrs appear, which increases the surface roughness value by 2-4 levels.
Machining vibration in the cutting process, affected by the cutting force, the tool and workpiece often have strong vibration, resulting in obvious surface vibration marks. The machine tool increases the surface roughness value of the workpiece, and in serious cases, it will also produce the phenomenon of edge collapse, which will seriously deteriorate the surface quality.
