Surface texture is one of the important factors that control friction and transfer layer formation during sliding. Considerable efforts have been made to study the influence of surface texture on friction and wear during sliding conditions. Surface textures can be isotropic or anisotropic.
Sometimes, stick-slip friction phenomena can be observed during sliding, depending on surface texture, one of the key elements influencing friction and the creation of transfer layers during sliding is surface roughness. A great deal of research has been done to determine how roughness affects wear and friction when sliding.
Well, in this reading, I’ll be exploring what Surface finish is, its diagram, units, symbols, chart, advantages and disadvantages & how it’s work.
Let’s Get Started!
What is Surface Finish?
Surface finish, also known as surface texture or surface topography, is the nature of a surface as defined by the three characteristics of lay, surface roughness, and waviness. [1] It comprises the small, local deviations of a surface from the perfectly flat ideal (a true plane).
Every manufacturing process creates a different surface texture, such as the various machining techniques. In order to guarantee that the final texture is useable, the procedure is often optimized. An extra step will be implemented if needed to change the original texture.
The latter procedure might involve industrial etching/chemical milling, laser texturing, electrical discharge machining (EDM), honing, polishing, lapping, abrasive blasting, grinding (abrasive cutting), milling, lithography, or other procedures.
How Does Surface Finish Works?
Surface abnormalities, also known as lay, are a crucial aspect of the manufacturing process. Lay refers to the direction of the predominant surface pattern and can be parallel, perpendicular, circular, crosshatched, radial, multi-directional, or isotropic (non-directional).
It is often created during the manufacturing process and is used to reduce fabric waste by placing pattern elements onto cloth in the most cost-effective manner.
Waviness, on the other hand, is the measurement of surface abnormalities that are spaced further apart than surface roughness. This can be caused by warping, vibrations, or deflection during machining.
A waviness profile is produced for the assessment length once waviness is assessed over it. Surface roughness, sometimes abbreviated as roughness, refers to the total amount of dispersed surface abnormalities, which is often considered “surface finish” in engineering. A smoother surface or finer imperfections are denoted by a lower number.
Surface finish symbols include the basic surface finish symbol, which is a checkmark with the point resting on the surface to be specified. Variations of this symbol provide additional instructions.
The Surface Finish parameter, Ra, is widely used but is insufficient to fully describe a surface’s roughness. The performance of surfaces with the same Ra might vary greatly depending on the application.
Ra is the most commonly used surface finish parameter, but it is not sufficient to fully describe a surface’s roughness. Other factors, such as Rmax and Rz, are required to discern discrepancies.
Rmax measures the vertical separation between the highest point and the lowest valley, while Rz measures the average of the five biggest peaks to valley discrepancies within five sample lengths.
Surface finish consists of waviness, lay, and roughness, but it is common for only roughness to be specified on technical drawings. The roughest acceptable finish should be specified to minimize cost. Ra is average roughness, and its under-estimates surface height variations. In general, 7.2 x Ra = Rz (rough estimation only).
Advantages of surface finish include enhanced appearance, improved corrosion resistance, increased durability, reduced friction, better electrical conductivity, tighter tolerances, stress relief, and improved adhesion for coatings. Disadvantages include being sensitive to handling and packaging, potential damage from electrical tests, limited shelf life, and creep-corrosion.
