PPT: Measurement of Finish | Manufacturing Engineering - Mechanical Engineering PDF Download

 Page 1


•
Repetitive or random deviations from the normal 
surface which form the pattern of the surface.  Surface 
texture include roughness, waviness, lay and flows.
•
Every part’s surface is made up of texture and 
roughness which varies due to manufacturing 
techniques and the part structure itself.
•
Primary texture: lr/hr<50 (Roughness)
•
Secondary texture: lw/hw>50 (Waviness)
Surface Texture
Page 2


•
Repetitive or random deviations from the normal 
surface which form the pattern of the surface.  Surface 
texture include roughness, waviness, lay and flows.
•
Every part’s surface is made up of texture and 
roughness which varies due to manufacturing 
techniques and the part structure itself.
•
Primary texture: lr/hr<50 (Roughness)
•
Secondary texture: lw/hw>50 (Waviness)
Surface Texture
Terms used in surface roughness 
measurements
Page 3


•
Repetitive or random deviations from the normal 
surface which form the pattern of the surface.  Surface 
texture include roughness, waviness, lay and flows.
•
Every part’s surface is made up of texture and 
roughness which varies due to manufacturing 
techniques and the part structure itself.
•
Primary texture: lr/hr<50 (Roughness)
•
Secondary texture: lw/hw>50 (Waviness)
Surface Texture
Terms used in surface roughness 
measurements
1. Roughness :
Roughness consists of surface irregularities which result from the 
various machining process. These irregularities combine to form 
surface texture.
2. Roughness Height :
It is the height of the irregularities with respect to a reference line. It is 
measured in millimeters or microns or micro inches. It is also known as 
the height of unevenness.
3. Roughness Width :
The roughness width is the distance parallel to the nominal surface 
between successive peaks or ridges which constitute the predominate 
pattern of the roughness. It is measured in millimeters.
4. Roughness 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 always be greater than the roughness width in order to 
obtain the total roughness height rating.
Page 4


•
Repetitive or random deviations from the normal 
surface which form the pattern of the surface.  Surface 
texture include roughness, waviness, lay and flows.
•
Every part’s surface is made up of texture and 
roughness which varies due to manufacturing 
techniques and the part structure itself.
•
Primary texture: lr/hr<50 (Roughness)
•
Secondary texture: lw/hw>50 (Waviness)
Surface Texture
Terms used in surface roughness 
measurements
1. Roughness :
Roughness consists of surface irregularities which result from the 
various machining process. These irregularities combine to form 
surface texture.
2. Roughness Height :
It is the height of the irregularities with respect to a reference line. It is 
measured in millimeters or microns or micro inches. It is also known as 
the height of unevenness.
3. Roughness Width :
The roughness width is the distance parallel to the nominal surface 
between successive peaks or ridges which constitute the predominate 
pattern of the roughness. It is measured in millimeters.
4. Roughness 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 always be greater than the roughness width in order to 
obtain the total roughness height rating.
5. Lay :
Lay represents the direction of predominant surface pattern 
produced and it reflects the machining operation used to produce 
it.
6. Waviness Height:
Waviness height is the peak to valley distance of the surface 
profile, measured in millimeters.
7. Arithmetic Average (AA):
If X is the measured value from the profilometer, then the AA 
value can be calculated as shown below.
8. Root Mean Square (rms)
The rms value can be calculated as shown below. Its numerical 
value is about 11% higher than that of AA.
9. Flaws: Irregularity which occur at one place or widely varying 
intervals in surface. It include cracks, scratches etc.
Page 5


•
Repetitive or random deviations from the normal 
surface which form the pattern of the surface.  Surface 
texture include roughness, waviness, lay and flows.
•
Every part’s surface is made up of texture and 
roughness which varies due to manufacturing 
techniques and the part structure itself.
•
Primary texture: lr/hr<50 (Roughness)
•
Secondary texture: lw/hw>50 (Waviness)
Surface Texture
Terms used in surface roughness 
measurements
1. Roughness :
Roughness consists of surface irregularities which result from the 
various machining process. These irregularities combine to form 
surface texture.
2. Roughness Height :
It is the height of the irregularities with respect to a reference line. It is 
measured in millimeters or microns or micro inches. It is also known as 
the height of unevenness.
3. Roughness Width :
The roughness width is the distance parallel to the nominal surface 
between successive peaks or ridges which constitute the predominate 
pattern of the roughness. It is measured in millimeters.
4. Roughness 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 always be greater than the roughness width in order to 
obtain the total roughness height rating.
5. Lay :
Lay represents the direction of predominant surface pattern 
produced and it reflects the machining operation used to produce 
it.
6. Waviness Height:
Waviness height is the peak to valley distance of the surface 
profile, measured in millimeters.
7. Arithmetic Average (AA):
If X is the measured value from the profilometer, then the AA 
value can be calculated as shown below.
8. Root Mean Square (rms)
The rms value can be calculated as shown below. Its numerical 
value is about 11% higher than that of AA.
9. Flaws: Irregularity which occur at one place or widely varying 
intervals in surface. It include cracks, scratches etc.