CHAPTER 6 WEAR TESTING MEASUREMENT - …shodhganga.inflibnet.ac.in/bitstream/10603/34533/11/11_chapter6.pdf · CHAPTER 6 WEAR TESTING MEASUREMENT ... In this experiment, the test

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CHAPTER 6

WEAR TESTING MEASUREMENT

Wear is a process of removal of material from one or both of

two solid surfaces in solid state contact. As the wear is a surface removal

phenomenon and occurs mostly at outer surfaces, it is more appropriate and

economical to make surface modification of existing alloys than using the

wear resistant alloys.

6.1 EXPERIMENTAL PROCEDURE OF WEAR TEST

Dry sliding wear tests for different number of specimens was

conducted by using a pin-on-disc machine (Model: Wear & Friction

Monitor TR-20) supplied by DUCOM is shown in Figure 6.1.

Figure 6.1 Wear testing machine

85

The pin was held against the counter face of a rotating disc

(EN31 steel disc) with wear track diameter 60 mm. The pin was loaded

against the disc through a dead weight loading system. The wear test for all

specimens was conducted under the normal loads of 20N, 40N and a

sliding velocity of 2 and 4 m/s.

Wear tests were carried out for a total sliding distance of

approximately 3000 m under similar conditions as discussed above.

The pin samples were 30 mm in length and 12 mm in diameter. The

surfaces of the pin samples were slides using emery paper (80 grit size)

prior to test in order to ensure effective contact of fresh and flat surface

with the steel disc. The samples and wear track were cleaned with acetone

and weighed (up to an accuracy of 0.0001 gm using microbalance) prior to

and after each test. The wear rate was calculated from the height loss

technique and expressed in terms of wear volume loss per unit sliding

distance.

In this experiment, the test was conducted with the following

parameters:

1. Load

2. Speed

3. Distance

In the present experiment the parameters such as speed, time

and load are kept constant throughout for all the experiments.

These parameters are given in Table 6.1.

86

Table 6.1 Parameter taken constant during sliding wear test

Pin material Al, Al/C, Al/C/3B4C, Al/C/6B4C, Al/C/9B4C

Disc material EN 31 steel

Pin dimension Cylinder with diameter 12 mm height 30 mm

Sliding speed (m/s) 2, 4

Normal load 20, 40

Sliding distance (m) 3000

6.2 PIN-ON-DISC TEST

In this study, Pin-on-Disc testing method was used for

tribological characterization. The test procedure is as follows:

Initially, pin surface was made flat such that it will support the

load over its entire cross-section called first stage. This was

achieved by the surfaces of the pin sample ground using emery

paper (80 grit size) prior to testing

Run-in-wear was performed in the next stage/ second stage.

This stage avoids initial turbulent period associated with friction

and wear curves

Final stage/ third stage is the actual testing called constant/

steady state wear. This stage is the dynamic competition

between material transfer processes (transfer of material from

pin onto the disc and formation of wear debris and their

subsequent removal). Before the test, both the pin and disc were

cleaned with ethanol soaked cotton (Surappa et al 2007)

87

Before the start of each experiment, precautionary steps were

taken to make sure that the load was applied in normal direction. Figure 6.2

represents a schematic view of Pin-on-Disc setup.

Figure 6.2 Schematic views of the pin-on-disk apparatus

6.2.1 Weight Loss

The alloy and composite samples are cleaned thoroughly with

acetone. Each sample is then weighed using a digital balance having an

accuracy of ± 0.1 mg. After that, the sample is mounted on the pin holder

of the tribometer ready for wear test. For all experiments, the sliding

speeds are adjusted to 2 and 4 m/s.

The specific wear rates of the materials were obtained by

W = w where W denotes specific wear rates in mm3/N- w is the

weight loss measured in grams,

density of the worn material in g/mm3 and F is the applied load in N.

Weight loss of the alloy and composite samples in grams is shown in

Table 6.2.

88

Table 6.2 Data of cumulative wear loss of alloy and composites

Weight loss of alloy and composite

S.No. Specimen

Name

Sliding Speed 2m/s Sliding Speed 4m/s

Initial

weight

(gm)

Final

weight

(gm)

Weight

loss

(gm)

Initial

weight

(gm)

Final

weight

(gm)

Weight

loss

(gm)

1 LM 25 8.27122 8.246 0.02522 8.27122 8.2422 0.02902

2 LM 25 + C 8.09076 8.073 0.01776 8.09076 8.067 0.02376

3 LM 25+C

+ 3%B4C 8.16358 8.1494 0.01418 8.16358 8.14182 0.02176

4 LM 25+C

+ 6%B4C 8.00555 7.9927 0.01285 8.00555 7.985 0.02055

5 LM 25+C

+ 9%B4C 8.35572 8.3444 0.01132 8.35572 8.33629 0.01943

Figure 6.3 Weight loss of alloy and composite with 2 m/s

89

Figure 6.4 Weight loss of alloy and composite with 4 m/s

Figures 6.3 and 6.4 show the cumulative weight loss of the alloy

specimen after addition of graphite and boron carbide produced with the

help of stir casting technique. After addition of reinforced material the

sliding wear decreases significantly or says that weight loss is decreasing

as the graphite and boron carbide addition is increasing as compared to

matrix metal.

6.2.2 Wear Calculation

1. Area

Cross sectional Area,

2. Volume loss

Volume loss = Cross sectional Area x Height loss

3. Wear rate

Wear rate = Volume loss / Sliding distance

90

4. Wear resistance

Wear resistance = 1/ Wear rate

5. Specific wear rate

Specific wear rate = Wear rate/load

6.2.3 Graphs

Table 6.3 Specimen vs wear rate (mm3/m)

Specimen Wear rate (mm3/m)

2 m/s 4 m/s

p 6.58676928 40.49484735

g4 1.70248684 20.06797604

b3 1.27498018 17.07768475

b6 1.13700184 14.43573299

b9 0.90552998 8.4144354

Figure 6.5 Specimen vs wear rate (mm3/m) with 2 and 4 m/s

91

LM-25 and composites reinforced with boron carbide and

graphite particles of size ranges (200 meshes) at a load of 20, 40 N and

total time is 5 minutes. It can be attributed to the increase in hardness of the

material due to the presence of hard ceramic particles. Material removal in

a ductile material such as aluminium alloy matrix is due to the indentation

and ploughing action of the sliding disc which is made from hard steel

material (EN31 steel disc). Incorporation of hard graphite and B4C

particles in the Al alloy LM25 restricts such ploughing action of hard steel

counterpart and improves the wear resistance. Comparing the wear

properties of composites reinforced with graphite and B4C particles, it is

observed that despite their higher hardness, composites reinforced with

graphite and B4C particles show improved wear resistance as compared to

Al 6061 composites reinforced with SiC particles (Sanjeev Das et al 2006).

Table 6.4 Specimen vs wear resistance (m/mm3)

SpecimenWear resistance (m/mm3)

2 m/s 4 m/s

p 0.151819497 0.0246945

g4 0.587376053 0.049830636

b3 0.784325918 0.058555947

b6 0.879506053 0.069272548

b9 1.104325668 0.118843387

92

Figure 6.6 Specimen vs wear resistance (m/mm3) with 2 and 4 m/s

Figure 6.6 shows the wear resistance as a function of time for

the LM25 and composites reinforced with boron carbide and graphite

particles of size ranges (200 meshes) at a load of 20, 40 N and total time is

5 minutes. It is observed that wear resistance of LM25 increased.

Table 6.5 Specimen vs specific wear rate (mm3/Nm)

Specimen Specific wear rate (mm3/Nm)

2 m/s 4 m/s

p 0.329338464 2.024742368

g4 0.085124342 1.003398802

b3 0.063749009 0.853884238

b6 0.056850092 0.72178665

b9 0.045276499 0.42072177

93

Figure 6.7 Specimen vs specific wear rate (mm3/Nm) with 2 and 4

m/s

Figure 6.7 shows the specific wear rate as a function of time for

the LM25 and composites reinforced with boron carbide and graphite

particles of size ranges (200 mesh) at a load of 20, 40 N and total time is

5 minutes. It is observed that specific wear rate of LM25 decreased.

6.3 SEM MICRO GRAPH OF AL/4 WT% C WITH 2 M/S

The worn surface of the Al/4% graphite composite is shown in

Figure 6.8. It clearly exhibits the presence of deep permanent grooves and

fracture of the oxide layer, which may have caused the increase of wear

loss. However, the worn surfaces of the two composites exhibit finer

grooves and slight plastic deformation at the edges of the grooves.

The surface also appears to be smooth because of the graphite

reinforcement content.

94

(a) (b)

(c) (d)

Figure 6.8 Typical SEM micro graph of Al/4 wt% C with 2 m/s

6.3.1 SEM Micro Graph of Al/4 wt% C/3, 6, 9 wt% B4C with

2 m/s

The worn surfaces of the composite AlMMC’s are shown in

Figures 6.9 to 6.11. Indistinct grooves and fine scratches were formed on

the worn surface. The wear mechanism are characterised by the formation

of the grooves, which are produced by the ploughing action of hard

asperities on the counter disc and hardened worn debris. Increase in boron

carbide would results in decrease in wear.

95

(a) (b)

(c) (d)

Figure 6.9 Typical SEM micro graph of Al/4 wt% C/ 3 wt % of B4C

with 2 m/s

(a) (b)

96

(c) (d)


with 2 m/s

(a) (b)

(c) (d)


with 2 m/s

97

6.3.2 SEM Micro Graph of Al/4 wt% C with 4 m/s

(a) (b)

(c) (d)

Figure 6.12 Typical SEM micro graph of Al/4 wt% C/ 3 with 4 m/s

The SEM image of aluminium composite was shown in

Figure 6.12. It shows that the worn surfaces of the two composites exhibit

finer grooves and slight plastic deformation at the edges of the grooves.

The surface also appears to be smooth because of the graphite

reinforcement content.

98

6.3.3 SEM Micro Graph of Al/4 wt% C/3, 6, 9 wt% B4C with

4 m/s

(a) (b)

(c) (d)


with 4 m/s

(a) (b)

99

(c) (d)


with 4 m/s

The SEM image of the aluminium composite is shown in

Figures 6.13 - 6.14. It provides that the presence of boron particle increases

the hardness and reduces the metal removal rate reduced to 7% when

compared to previous combination.

(a) (b)

100

(c) (d)


with 4 m/s

At a sliding speed of 4 m/s, the wear rate shows a lowering

trend which indicates the less removal of material from the surface.

The micrograph shows the removal of material by delamination.

Apart from this, cracks are generated along with particle pull out at the

surface. Figure 6.15 shows the presence of a large number of grooves over

the entire surface.

6.4 WEAR BEHAVIOUR

The aim of the experimental plan is to find the important factors

and the combination of factors influencing the wear process to achieve the

minimum wear rate and COF. The experiments were developed based on

an OA, with the aim of relating the influence of sliding speed, applied load

and sliding distance. These design parameters are distinct and intrinsic

feature of the process that influence and determine the composite

performance. Taguchi recommends analyzing the S/N ratio using

conceptual approach that involves graphing the effects and visually

identifying the significant factors.

101

The above mentioned pin on disc test apparatus was used to

determine the sliding wear characteristics of the composite. Specimens of

size 12 mm diameter and 10 mm length were cut from the cast samples,

and then machined. The contact surface of the cast sample (pin) was made

flat so that it should be in contact with the rotating disk. During the test, the

pin was held pressed against a rotating EN31 carbon steel disc by applying

load that acts as a counterweight and balances the pin. The track diameter

was varied for each batch of experiments in the range of 50 mm to 100 mm

and the parameters such as the load, sliding speed and sliding distance was

varied in the range given in Table 6.6. An LVDT (load cell) on the lever

arm helps determine the wear at any point of time by monitoring the

movement of the arm. Once the surface in contact wears out, the load

pushes the arm to remain in contact with the disc. This movement of the

arm generates a signal which is used to determine the maximum wear and

the COF is monitored continuously as wear occurs and graphs between

COF and time was monitored for both of the specimens, i.e., aluminium

LM25, 4% of C, 3% of B4C, 6% of B4C, 9% of B4C.

Further, weight loss of each specimen was obtained by weighing

the specimen before and after the experiment by a single pan electronic

weighing machine with an accuracy of 0.0001g after thorough cleaning

with acetone solution.

The results for various combinations of parameters were

obtained by conducting the experiment as per the OA and shown in

Table 6.7. The measured results were analyzed using the commercial

software MINITAB 15 specifically used in DOE applications.

102

Table 6.6 Process parameters and levels

Level Load (N)Sliding Speed, S

(m/s)

Sliding Distance, D

(m)

1 20 2 1000

2 40 4 2000

3 60 6 3000

6.5 PLAN OF EXPERIMENTS

The dry sliding wear test was performed with three parameters:

applied load, sliding speed and sliding distance and varying them for three

levels. According to the rule that DOF for an OA should be greater than or

equal to the sum of those wear parameters, a L9 OA which has 9 rows and

3 columns was selected as shown below:

Table 6.7 Orthogonal array L9 of Taguchi

Experimental No. Column 1 Column 2 Column 3

1 1 1 1

2 1 2 2

3 1 3 3

4 2 1 2

5 2 2 3

6 2 3 1

7 3 1 3

8 3 2 1

9 3 3 2

103

The selection of OA depends on three items in order of priority,

viz., the number of factors and their interactions, number of levels of the

factors and the desired experimental resolution or cost limitations. A total

of 9 experiments were performed based on the run order generated by the

Taguchi model. The response of the model is wear rate and COF. In OA,

the first column is assigned to applied loads, second column is assigned to

sliding speed and third column is assigned to sliding distance and the

remaining columns are assigned to their interactions. The objective of the

model is to minimize the wear rate and COF. The Signal to Noise (S/N)

ratio, which condenses the multiple data points within a trial, depends on

the type of characteristic being evaluated. In this study, “smaller the better”

characteristic was chosen to analyze the dry sliding wear resistance.

The response table for signal to noise ratios show the average of selected

characteristics of each level of the factor. This table includes the ranks

based on the delta statistics, which compares the relative value of the

effects. S/N ratio is a response which consolidates repetitions and the effect

of noise levels into one data point. Analysis of variance of the S/N ratio is

performed to identify the statistically significant parameters.

6.6 RESULTS AND DISCUSSIONS

The aim of the experimental plan is to find the important factors

and the combination of factors influencing the wear process to achieve the

minimum wear rate and COF. The experiments were developed based on

an OA, with the aim of relating the influence of sliding speed, applied load

and sliding distance. These design parameters are distinct and intrinsic

feature of the process that influence and determine the composite

performance. Taguchi recommends analyzing the S/N ratio using

conceptual approach that involves graphing the effects and visually

identifying the significant factors.

104

6.6.1 Results of Statistical Analysis of Experiments

The results for various combinations of parameters were

obtained by conducting the experiment as per the OA. The measured

results were analyzed using the commercial software MINITAB 15

specifically used in DOE applications. Tables 6.8 to 6.22 shows the

experimental results average of two repetitions for wear rate and COF.

To measure the quality characteristics, the experimental values are

transformed into a signal to noise ratio. The influence of control parameters

such as load, sliding speed and sliding distance on wear rate and COF has

been analyzed using signal to noise response table.

The ranking of process parameters using signal to noise ratios

obtained for different parameter levels for wear rate and COF are given for

aluminium LM25, 4% of C, 3% of B4C, 6% of B4C, 9% of B4C.

The control factors are statistically significant in the Signal to Noise ratio

and it could be observed that the sliding distance is a dominant parameter

on the wear rate and COF followed by applying load and sliding speed.

The analysis of these experimental results using S/N ratios gives the

optimum conditions resulting in minimum wear rate and COF.

6.6.2 Analysis of Variance Results for Wear Test

The experimental results were analyzed with ANOVA, which is

used to investigate the influence of the considered wear parameters,

namely, applied load, sliding speed and sliding distance that significantly

affects the performance measures. By performing analysis of variance, it

can be decided which independent factor dominates over the other and the

percentage contribution of that particular independent variable. Aluminium

LM25, 4% of C, 3% of B4C, 6% of B4C and 9% of B4C of the ANOVA

105

results for wear rate and COF for three factors varied at three levels and

interactions of those factors. This analysis is carried out for a significance

= 0.05, i.e. for a confidence level of 95%. Sources with a P-value

less than 0.05 were considered to have a statistically significant

contribution to the performance measures.

Table 6.8 Responses table for S/N ratio for wear (Al – LM 25)

S.No. Load

(N)

Speed

(m/s)

Distance

(m)

Wear

(mm3/m) C.O.F

S/N

ratio

C.O.F

S/N

ratio

wear

rate

1 20 2 1000 0.006580 0.648 43.6355 3.76850

2 20 4 2000 0.005370 0.628 45.4005 4.04081

3 20 6 3000 0.003550 0.614 48.9954 4.23663

4 40 2 1000 0.010120 0.627 39.8964 4.05465

5 40 4 2000 0.007662 0.632 42.3132 3.98566

6 40 6 3000 0.006182 0.657 44.1774 3.64869

7 60 2 1000 0.013670 0.620 37.2846 4.15217

8 60 4 2000 0.012960 0.632 37.7479 3.98566

9 60 6 3000 0.011430 0.618 38.8391 4.18023

106

Table 6.9 Responses table for S/N ratio of coefficient of friction (Al

– LM 25)

Level Load (N) Speed (m/s) Distance (m)

1 46.01 40.27 40.27

2 42.13 41.82 41.82

3 37.96 44.00 44.00

Delta 8.05 3.73 3.73

Rank 1 2 3

Table 6.10 Main effects for plot for S/N ratios - coefficient of friction


1 4.015 3.992 3.992

2 3.896 4.004 4.004

3 4.106 4.022 4.022

Delta 0.210 0.030 0.030

Rank 1 2 3

Figure 6.16 Main effects for plot for S/N ratios - wear rate

107


Figure 6.18 Main effects for plot for S/N ratios - coefficient of friction

108


Table 6.11 Responses table for S/N ratio for wear (Al-LM 25/4% C)

S.No. Load (N)

Speed(m/s)

Distance(m)

Wear(mm3/m) C.O.F

S/N Ratio c.o.f

S/N Ratio Wear Rate

1 20 2 1000 0.01702 0.527 35.3808 5.56379

2 20 4 2000 0.01638 0.513 35.7137 5.79765

3 20 6 3000 0.01618 0.502 35.8204 5.98593

4 40 2 1000 0.05016 0.583 25.9928 4.68663

5 40 4 2000 0.04988 0.564 26.0415 4.97442

6 40 6 3000 0.04762 0.573 26.4442 4.83691

7 60 2 1000 0.09863 0.543 20.1198 5.30400

8 60 4 2000 0.96540 0.532 0.3059 5.48177

9 60 6 3000 0.09321 0.521 20.6107 5.66325

109

Table 6.12 Responses table for S/N ratio of coefficient of friction

(Al - LM 25/4% C)

Level Load(N) Speed(m/s) Distance(m)

1 35.64 27.16 27.16

2 26.16 20.69 20.69

3 13.68 27.63 27.63

Delta 21.96 6.94 6.94

Rank 1 2 3



1 5.782 5.185 5.185

2 4.833 5.418 5.418

3 5.483 5.495 5.495

Delta 0.950 0.311 0.311

Rank 1 2 3


110



111


Table 6.14 Responses table for S/N ratio for wear (Al – LM 25/4%

C/3% B4C

S.No. Load (N)

Speed(m/s)

Distance(m)

Wear(mm3/m)

C.O.F S/N

ratioC.O.F

S/N Ratio Wear Rate

1 20 2 1000 0.01279 0.571 37.8626 37.8626

2 20 4 2000 0.01209 0.563 38.3515 38.3515

3 20 6 3000 0.01194 0.554 38.4599 38.4599

4 40 2 1000 0.04269 0.586 27.3935 27.3935

5 40 4 2000 0.04154 0.574 27.6307 27.6307

6 40 6 3000 0.04021 0.536 27.9133 27.9133

7 60 2 1000 0.08263 0.526 21.6572 21.6572

8 60 4 2000 0.08154 0.516 21.7726 21.7726

9 60 6 3000 0.08012 0.552 21.9252 21.9252

112


– LM 25/4% C/3% B4C))


1 38.22 28.97 28.97

2 27.65 29.25 29.25

3 21.79 29.43 29.43

Delta 16.44 0.46 0.46

Rank 1 2 3



1 38.22 28.97 28.97

2 27.95 29.25 29.25

3 21.79 29.43 29.43

Delta 16.44 0.46 0.46

Rank 1 2 3


113


Figure 6.26 Main effects for plot for S/N ratios – coefficient of friction

114


Table 6.17 Responses table for S/N ratio for wear (Al - LM 25/ 4%

C/ 6%B4 MMC)

S.No. Load(N)

Speed (m/s)

Distance(m)

Wear(mm3/m) C.O.F

S/N ratio

C.O.F

S/N ratio wear rate

1 20 2 1000 0.01370 0.623 37.2656 37.2656

2 20 4 2000 0.01049 0.614 39.5845 39.5845

3 20 6 3000 0.00989 0.609 40.0961 40.0961

4 40 2 1000 0.03608 0.632 28.8547 28.8547

5 40 4 2000 0.03421 0.618 29.3169 29.3169

6 40 6 3000 0.03102 0.602 30.1672 30.1672

7 60 2 1000 0.07082 0.625 22.9969 22.9969

8 60 4 2000 0.69830 0.617 3.1192 3.1192

9 60 6 3000 0.68730 0.631 3.2571 3.2571

115

Table 6.18 Responses table for S/N ratio of coefficient of friction

(Al - LM 25/ 4% C/ 6%B4 MMC)


1 38.982 29.706 29.706

2 29.446 24.007 24.007

3 9.761 24.507 24.507

Delta 29.191 5.699 5.699

Rank 1 2 3



1 38.982 29.706 29.706

2 29.446 24.007 24.007

3 9.791 24.507 24.507

Delta 29.191 5.699 5.699

Rank 1 2 3


116



117


Table 6.20 Responses table for S/N ratio for wear (Al - LM 25/ 4% C

and 9% B4 MMC)

S.No. Load (N)

Speed(m/s)

Distance(m)

Wear(mm3/m) C.O.F

S/N Ratio C.O.F

S/N Ratio Wear Rate

1 20 2 1000 0.00905 0.544 40.8670 40.8670

2 20 4 2000 0.00896 0.536 40.9538 40.9538

3 20 6 3000 0.00884 0.526 41.0710 41.0710

4 40 2 1000 0.02103 0.588 33.5432 33.5432

5 40 4 2000 0.02094 0.564 33.5805 33.5805

6 40 6 3000 0.02086 0.553 33.6137 33.6137

7 60 2 1000 0.04302 0.579 27.3266 27.3266

8 60 4 2000 0.04104 0.553 27.7359 27.7359

9 60 6 3000 0.04092 0.543 27.7613 27.7613

118


– LM 25/ 4% C and 9% B4 MMC)


1 40.96 33.91 33.91

2 33.58 34.09 34.09

3 27.61 34.15 34.15

Delta 13.36 0.24 0.24

Rank 1 2 3


119



1 40.96 33.91 33.91

2 33.58 34.09 34.09

3 27.61 34.15 34.15

Delta 13.36 0.24 0.24

Rank 1 2 3


120



121

The interaction terms have little or no effect on the coefficient

of friction & the pooled errors accounts only 0.5% & 1.4%. From the

analysis of variance & S/N ratio, it is inferred that the sliding distance has

the highest contribution on wear rate & COF followed by load & sliding

speed.

6.7 ANOVA

Table 6.23 Analysis of variance for wear (coded units) with LM 25

Source DF Seq SS Adj SS Adj MS F P

Main Effects 2 0.00009896 0.00009896 0.00004948 92.95 0.000

2-Way

Interactions1 0.00000016 0.00000016 0.00000016 0.29 0.611

Residual

Error 5 0.00000266 0.00000266 0.00000053

Total 8 0.00010177

It can be observed that for AMMCs that the sliding distance has

the highest influence on wear rate. Hence sliding distance is an important

control factor to be taken into consideration during the wear process

followed by applied loads and sliding speed respectively, it can observe

that the load has the highest contribution, followed by sliding distance and

sliding speed for Al LM25 with reinforcement combination of MMCs.

The interaction terms have little or no effect on COF & the

pooled errors accounts. From the analysis of variance and S/N ratio, it is

inferred that the sliding distance has the highest contribution on wear rate

& COF followed by load & sliding speed. These values are shown in the

Tables 6.23 to 6.32.

122

Table 6.24 Analysis of variance for C.O.F (coded units) with LM 25

Source DF Seq SS Adj SS Adj MS F PMain Effects

2 0.00007267 0.00007267 0.00003633 0.15 0.867

2-Way Interactions

1 0.00025600 0.00025600 0.00025600 1.03 0.356

Residual Error

5 0.00124133 0.00124133 0.00024827

Total 8 0.00157000

Table 6.25 Analysis of variance for wear (coded units) with LM25/C

Source DF Seq SS Adj SS Adj MS F P Main Effects

2 0.204498 0.204498 0.102249 0.93 0.454

2-Way Interactions

1 0.000005 0.000005 0.000005 0.00 0.995

Residual Error

5 0.550155 0.550155 0.110031

Total 8 0.754658

Table 6.26 Analysis of variance for C.O.F (coded units) LM25/C

Source DF Seq SS Adj SS Adj MS F P

Main Effects 2 0.00102750 0.00102750 0.00051375 0.49 0.640

2-Way

Interactions1 0.00000225 0.00000225 0.00000225 0.00 0.965

Residual

Error 5 0.00525981 0.00525981 0.00105196

Total 8 0.00628956

123

Table 6.27 Analysis of variance for wear (coded units) with

LM25/C/3B4C

Source DF Seq SS Adj SS Adj MS F P Main Effects 2 0.00717965 0.00717965 0.00358983 309.48 0.0002-Way Interactions

1 0.00000069 0.00000069 0.00000069 0.06 0.817

Residual Error

5 0.00005800 0.00005800 0.00001160

Total 8 0.00723834

Table 6.28 Analysis of variance for C.O.F (coded units) with

LM25/C/3B4C

Source DF Seq SS Adj SS Adj MS F PMain Effects 2 0.0017528 0.0017528 0.0008764 2.06 0.223 2-Way Interactions

1 0.0004622 0.0004622 0.0004622 1.09 0.345

Residual Error

5 0.0021278 0.00212780.0004256

Total 8

Table 6.29 Analysis of variance for wear (coded units) with

LM25/C/6B4C

Source DF Seq SS Adj SS Adj MS F P Main Effects 2 0.39871 0.39871 0.19935 5.18 0.0602-Way Interactions

1 0.09619 0.09619 0.09619 2.50 0.175

Residual Error

5 0.19241 0.19241 0.03848

Total 8 0.68731

124

Table 6.30 Analysis of variance for C.O.F (coded units) with LM25/C/6B4C

Source DF Seq SS Adj SS Adj MS F P Main Effects 2 0.0003622 0.0003622 0.00018108 2.81 0.152 2-Way Interactions

1 0.0001000 0.0001000 0.00010000 1.55 0.268

Residual Error

5 0.0003218 0.0003218 0.00006437

Total 8 0.0007840

Table 6.31 Analysis of variance for wear (coded units) with LM25/C/9B4C


2 0.00160594 0.00160594 0.00080297 103.08 0.000

2-Way Interactions

1 0.00000089 0.00000089 0.00000089 0.11 0.749

Residual Error

5 0.00003895 0.00003895 0.00000779

Total 8 0.00164578

Table 6.32 Analysis of variance for C.O.F (coded units) with LM25/C/9B4C


2 0.00211367 0.00211367 0.00105683 5.19 0.060

2-Way Interactions

1 0.00008100 0.00008100 0.00008100 0.40 0.556

Residual Error

5 0.00101733 0.00101733 0.00020347

Total 8 0.00321200

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