surface-roughness.pdf

6
Name: Albarakah, Raed Surface Roughness MSE412 Abstract: In this experiment we measured the surface roughness of aluminum 6061. We used a surface profilometer to obtain the surface roughness reading. The aluminum 6061 has eight grooves each groove was mailed at different conditions. We took several reading at each groove. We calculated the mean square root after that we plotted R q charts for different feed rate 12, 24 and 36 Ipm. These charts were compared to understand the best choice. This experiment gave us a clear view about CNC milling tools. Operating milling operation with more flute minimize the surface roughness. Introduction: Regardless of the method of production, all surfaces have their own set of characteristics, referred to as surface texture. Although the description of surface texture as a geometrical property can be complex, certain guidelines have been established for identifying surface texture in term of well-define and measurable quantity. 1- Flaws, or defect are random irregularities, such as scratch 2- Lay, or directionality, is the direction of the predominant surface pattern and is usually visible to the naked eye. 3- Waviness is a recurrent deviation from a flat surface, much like wave on the surface of water. It is described and measured in term of (1) the space between adjacent crest of the waves (waviness width) and (2) the height between crests and valleys of the waves (waviness height). 4- Roughness consists of closely spaced irregular deviations on a scale smaller than that for waviness.

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Page 1: Surface-Roughness.pdf

Name: Albarakah, Raed Surface Roughness MSE412

Abstract:

In this experiment we measured the surface roughness of aluminum 6061. We used a

surface profilometer to obtain the surface roughness reading. The aluminum 6061 has eight

grooves each groove was mailed at different conditions. We took several reading at each groove.

We calculated the mean square root after that we plotted Rq charts for different feed rate 12, 24

and 36 Ipm. These charts were compared to understand the best choice. This experiment gave us

a clear view about CNC milling tools. Operating milling operation with more flute minimize the

surface roughness.

Introduction:

Regardless of the method of production, all surfaces have their own set of characteristics,

referred to as surface texture. Although the description of surface texture as a geometrical

property can be complex, certain guidelines have been established for identifying surface texture

in term of well-define and measurable quantity.

1- Flaws, or defect are random irregularities, such as scratch

2- Lay, or directionality, is the direction of the predominant surface pattern and is usually

visible to the naked eye.

3- Waviness is a recurrent deviation from a flat surface, much like wave on the surface of

water. It is described and measured in term of (1) the space between adjacent crest of the

waves (waviness width) and (2) the height between crests and valleys of the waves

(waviness height).

4- Roughness consists of closely spaced irregular deviations on a scale smaller than that for

waviness.

Page 2: Surface-Roughness.pdf

Name: Albarakah, Raed Surface Roughness MSE412

Figure 1: Terminology and symbols of surface finish.

Surface Roughness

Surface roughness is generally described by two methods. The arithmetic mean value, Ra,

formerly identified as AA (for arithmetic average) or as CLA (for center-line average)

Ra=

Where all ordinates ya,yb,yc,…, are absolute values.

Ra: refer to continuous surface or wave, as is commonly encountered in analog signal

processing.

The root mean square average , Rq , formerly identified as RMS ( for root mean square) ,

is defined as

Rq= √

The units generally used for surface roughness are µm or µin.

The maximum roughness height, Rt , may also be used as a measure of surface roughness.

Defined as the vertical distance from the deepest trough to the highest peak, it indicated the

amount of material that has to be removed in order to obtain a smooth surface by various means,

such as polishing.

Page 3: Surface-Roughness.pdf

Name: Albarakah, Raed Surface Roughness MSE412

Experimental procedure:

A surface profilometer were passed through eight grooves. Reading from each groove

was taken in three sides right, left and middle. We set these values in a table including the

milling conditions. There are verities of cutting conditions. There are several type of flutes two

and four with different feed rate twelve and twenty four. Four grooves were milled without any

lubricants. Surface roughness’s was measured using arithmetic mean value, Ra. We draw a

graph to show the surface roughness versus machine conditions, furthermore, a comparison were

made to obtain optimal value.

Result and discussion:

Surface Roughness measurements for Aluminum 6061

Page 4: Surface-Roughness.pdf

Name: Albarakah, Raed Surface Roughness MSE412

Table one for 12 Ipm feed rate with and without lubricants

Table 1: A profilometer measurements for 12 Ipm Feed rate

2 Flute (12 Ipm)

4 Flute (12 Ipm) 2 Flute (12 Ipm) W/O

4 Flute (12 Ipm) W/O

18 31 44 42

52 53 69 69

60 32 54 44

28 45 70 49

Rq 43.0 41.3 60.2 52.1

Table Two for 24 Ipm feed rate with and without lubricant

Table 2: A Profilometer measurements for 24 Ipm feed rate

2 Flute (24 Ipm)

4 Flute (24 Ipm) 2 Flute (24 Ipm) W/O

4 Flute (24 Ipm) W/O

53 67 49 68

32 74 80 63

54 73 65 69

46 72 35 63

Rq 47.1 71.6 59.7 65.8

Table Three 36 Ipm feed rate with and without lubricant

Table 3: A profilometer measurements for 36 feed rate

2 Flute (36 Ipm)

4 Flute (36 Ipm)

6 Flute (36 Ipm)

2 Flute (36 Ipm) W/O

4 Flute (36 Ipm) W/O

6 Flute (36 Ipm) W/O

82 89 8 90 76 5

56 80 17 67 80 18

85 74 9 84 98 7

55 96 12.03 92 80 11.52

Rq 70.9 85.2 13.0 83.8 83.9 13

Page 5: Surface-Roughness.pdf

Name: Albarakah, Raed Surface Roughness MSE412

Root mean square average Rq were plotted in three different charts to show the machine

conditions versus the surface roughness.

Figure 2: mean squear root Rq for 12 Ipm

Figure 3: mean square root for 24 Ipm

Figure 4: mean square root Rq for 36 Ipm

0.0

50.0

100.0

2 Flute (12 Ipm) 4 Flute (12 Ipm) 2 Flute (12 Ipm)W/O

4 Flute (12 Ipm)W/O

12 Ipm

12 Ipm

0.0

20.0

40.0

60.0

80.0

2 Flute (24 Ipm) 4 Flute (24 Ipm) 2 Flute (24 Ipm)W/O

4 Flute (24 Ipm)W/O

24 Ipm

24 Ipm

0.0

20.0

40.0

60.0

80.0

100.0

2 Flute (36Ipm)

4 Flute (36Ipm)

6 Flute (36Ipm)

2 Flute (36Ipm) W/O

4 Flute (36Ipm) W/O

6 Flute (36Ipm) W/O

36 Ipm

36 Ipm

Page 6: Surface-Roughness.pdf

Name: Albarakah, Raed Surface Roughness MSE412

First graphic shows 4 flute with lubricant has the best surface roughness. This information gives

you a clue about milling apart. Milling a part with more flutes makes smother surface with fixed

cutting rate at 12 Ipm

Second graphic shows 2 flute with lubricant has best surface roughness. These measurements

help in selection of milling tools. In milling a part of aluminum with feed rate 24 Ipm it’s better

to choose 2 Flute.

Third Chart shows a good result of surface roughness that’s due to high feed rate at 36 Ipm. Six

flutes with 36 Ipm give minimum mean square root at 13 µin.

Conclusion:

We concluded in aluminum cutting with low feed rate it’s better to select 2 flute. Second,

when operating milling machine with 24 Imp select two flutes. Two flutes shows smother

surface roughness in aluminum machining. Third, we conclude that with higher cutting speed for

its recommended to select six flutes for example, 36 Ipm

Reference:

1) SEROPE KALPAKJIAN, STEVEN R. SCHMID, 2008 ,MANUFACTURING

PROCESSES FOR ENGINEERING MATERIALS, PRENTICE HALL , NEW JERSEY