SURFACE FINISHING AND ITS TERMINOLOGIES
Hello mechons, welcome to MechGeni!, in this post we are going to see about the simple topic titled "surface Finishing". Here We will explain you about what is surface finishing , definitions of surface finishing, and the basic terminologies used in surface finishing.
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Ok, first let me start with
What is Surface Finishing
Normal people measure the surface of objects by touching the surface and sensing it. But we The Engineers not do that method. Here we will measure and the surface of an object by using some instruments. If we finish the surfaces there are some machines and tools to get smooth and fine finished surfaces. Examples : Grinding machine, CNC machine, etc.,
Definition of Surface finishing
The surface finish of an object is defined by the three basic characteristics namely waviness, surface roughness, and lay. It tells us the small, local deviations of a surface from the ideal surface(Perfectly flat).
Or
We can define repetitive or random deviations from the normal surface which form the pattern of the surface.
If we machine the material, we won't get perfectly finished material due to some departures from ideal conditions.
Surface irregularities have a pattern and are oriented in a particular direction depending on the factors that cause these irregularities in the first place.
Surface irregularities arise due to the following factors
1. Feed marks of cutting tools
2. Chatter marks on the workpiece due to vibrations caused during the manufacturing process.
3. Irregular surface on the object due to the rupture of workpiece material during the metal cutting process.
4. Surface vibrations occur due to the deformation of the workpiece under the action of cutting forces.
5. Irregularities in the machine tool itself like lack of straightness of guideways.
Terminologies used in Surface Finishing
Some of the basic terminologies that must know about Surface finishing are as follows.
- Real surface
- Geometrical Surface
- Effective Surface
- Waviness
- Surface texture
- Surface roughness
- Roughness height
- Roughness width
- Roundness width cut-off
- Lay
- Waviness height
- Flaws
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| (Terminologies labelled) |
Real surface
It is the surface limiting the body and separating it from the surrounding surface.
Geometrical Surface
It is the surface prescribed by the design or by the process of manufacture, neglecting the errors of form and surface roughness.
Effective surface
It is the representation of the real surface obtained by instrumental means.
Waviness
Waviness is an error in form due to incorrect geometry of the tool producing the surface. On the other hand, roughness may be caused by problems such as tool chatter or traverse feed marks in a supposedly geometrically perfect machine. The spacing of waviness is the width between successive wave peaks or valleys. Waviness height is the distance from a peak to a valley.
Surface Texture
Random deviations from the normal surface that form the pattern of the surface. The surface texture contains roughness, waviness, lay, and flaws.
Surface Roughness
Roundness consists of surface irregularities that result from the various machining process. These irregularities combine to form the surface texture.
Roughness height
It is the height of the irregularities with respect to a datum line. It is measured in mm or microns or microinches. It is also called the height of unevenness.
Roughness width
It is the distance parallel to the nominal surface between successive peaks or ridges which constitute the predominate pattern of roughness. It is measured mm.
Roundness Width Cut Off
Roughness width cut off is the greatest spacing of respective surface irregularities to be included in the measurement of the average roughness height. It should greater than the roughness width to obtain the total roughness height rating.
Lay
Lay represents the direction of the predominant surface pattern produced and it reflects the machining operation used to produce it.
Waviness Height
Waviness is defined as height the peak to valley distance of the surface profile, measured in mm.
Flaws
Irregularity which occurs at one place or widely varying intervals on the surface. It includes cracks, scratches, etc.
Conclusion
That's all for now about the surface finishing and its terminologies
I hope that you understand about surface finishing, its definition and its basic terminologies.
If you have any queries or doubts or any suggestions put that in the comment box we will reply and rectify as fast as possible.