What is surface roughness?
Surface roughness evaluation parameters
Surface roughness measurement method
- Roughness sample comparison method
- Impression method measurement
- Stylus method measurement
- Light cutting method measurement
- Interferometry measurement
- Scattering method measurement
- Optical Probe Method
Factors affecting surface roughness
Plot aneurysm clipping
Plot aneurysm clipping refers to the accumulation of metal that falls from the workpiece during metal cutting to the front tool face. In addition plot aneurysm clipping is likely to fall to the surface of the workpiece.
Some workpiece materials are not suitable for cutting, then in the process of cutting, it is likely to have more serious damage, which will make the workpiece performance greatly reduced.
It is easy for the plot aneurysm clipping to occur when machining in middle speed. so the middle speed should be avoided, and the cutting speed should be increased or decreased reasonably according to the actual requirement.
Vibration also happens during machining, which creates ripple-like marks on the surface of the workpiece.
What is the major impact on the part of Surface roughness?
- Wear resistance, the rougher the surface, the faster the wear.
- The stability of the fitting, the rougher the surface, the easier it is to wear, so that the gap gradually grows during the work.
- The fatigue strength, corrosive gases or liquids could penetrate easily into the inner metal layer through the microscopic valleys on the surface and cause surface corrosion.
- The sealability, Rough surface can not be tightly fit, so gas or liquid leak through the gap.
- The contact stiffness, Contact stiffness is the ability of the joint surface of parts to resist deformation under external force.
- The measurement accuracy,The surface roughness of the measured the part and measuring tool will directly affect the accuracy of the measurement.
How to Improve Surface Roughness
- To choose the appropriate tool geometry.
- Before machining, make sure that the workpiece and tool are free of plot aneurysm clipping, and deal with the new plot aneurysm clipping as soon as possible.
- Select the correct workpiece material with high quality.
- Control the processing speed and avoid the medium machaning speed.
How to Selection of Surface Roughness Standard?
The selection of surface roughness parameters should not only meet the functional requirements of the surface of the part, but also consider economic rationality. On the premise of meeting the functional requirements, the cost could be reduce by choosing a larger surface roughness parameter value.
The working surface, such mating surface, sealing surface, friction surface with high movement speed and unit pressure require the smoothness of the surface, so the parameter value should be smaller.
The non-working surface, such as non-fitting surface and surface with low dimensional accuracy, donest need good smoothness, so the parameter value should be higher.