Three Elements Affecting CNC Machining Technic
The geometrical featuresof CNC finished surface includes surface roughness, surface undulation
and veis of surface working. Surface roughness is the elementary unit to constitute the geometrical
characteristic of finished surface. When workpiece surface is manchined by metal cutting tools,
the surface roughness is affected by geometrical factors, physical factors and machining
process technology.
1. Geometrical factors
Considering the geometrical factor, the shape of tools and geometric angle, especially
the feed of corner radius, tool cutting edge angle, tool minor cutting edge angle,
have great impact on surface roughness.
2. Physical factors
Considering the physical essence of cutting process, the circular bead of cutting edge
and extrusion and friction friction of cutting tools will make plastic deformation of
metallic material, which deteriorate seriously the surface roughness. Cuttings with
banding formed by manchined plastic materials, the front knief face will form hard
and thick built-up edge. The built-up edge will cut instead of front knief face and
cutting edge, which will make change of geometric angle and back engagement
of the cutting edge of cutting tool. The outline of built-up edge is irregular so it will
make tool marks on the surface of workpieces. Some built-up edges would inset
into workpiece surface, which increase the surface roughness.
3. Machining process technology
Considering the impact to the surface roughness of workpiece from machining
process technology, the main factors are related with cutting tools ,
the tecture of workpiece and the processing conditions.
