Log-Likelihood = -72.274 Goodness-of-Fit
Anderson-Darling adjusted = 0.981 Correlation Coefficient = 0.981
Characteristics of Distribution Standard 95.0 Normal CI
Estimate Error Lower Upper MeanMTTF 43.4791 21.2246 16.7017 113.188
Standard Deviation 96.8782 82.5198 18.2466 514.364 Median 17.8027 5.94771 9.24929 34.2660
First QuartileQ1 7.22820 2.74183 3.43675 15.2024 Third QuartileQ3 43.8472 16.6323 20.8478 92.2198
Interquartile RangeIQR 36.6190 15.2924 16.1524 83.0187
Maka diperoleh nilai MTTF komponen Beater PCD 80 mm 50x150x50 - Ø 17 mm sebesar 43,4791.
5.2.2.2. Perhitungan MTTF Komponen Screen 695-1120-3D-Ø 6 mm
Berdasarkan hasil perhitungan goodness of fit, selang waktu antar kerusakan pada komponen Screen 695-1120-3D-Ø 6 mm adalah berdistribusi weibull.
Perhitungan MTTF dapat dilakukan secara manual dan dengan bantuan software. Hasil perhitungan secara manual dapat dilihat pada Tabel 5.32.
Tabel 5.32. Perhitungan MTTF Komponen Screen 695-1120-3D-Ø 6 mm
i ti
Ft Rt=1-Ft
Xi=lnln1Rt
Yi=lnti Xi.Yi
Xi
2
1
6
0.03804 0.96196
-3.24970 1.79176
-5.82267 10.56052
2
7
0.09239 0.90761
-2.33364 1.94591
-4.54106 5.44589
3
14
0.14674 0.85326
-1.84080 2.63906
-4.85798 3.38856
4
17
0.20109 0.79891
-1.49387 2.83321
-4.23244 2.23163
5
17
0.25543 0.74457
-1.22093 2.83321
-3.45916 1.49068
6
18
0.30978 0.69022
-0.99223 2.89037
-2.86792 0.98452
7
18
0.36413 0.63587
-0.79239 2.89037
-2.29030 0.62788
8
18
0.41848 0.58152
-0.61229 2.89037
-1.76975 0.37490
9
20
0.47283 0.52717
-0.44594 2.99573
-1.33590 0.19886
10
21
0.52717 0.47283
-0.28898 3.04452
-0.87980 0.08351
11
21
0.58152 0.41848
-0.13796 3.04452
-0.42003 0.01903
12
21
0.63587 0.36413
0.01019 3.04452
0.03103 0.00010
Universitas Sumatera Utara
Tabel 5.32. Perhitungan MTTF … Lanjutan
i ti
Ft Rt=1-Ft
Xi=lnln1Rt
Yi=lnti Xi.Yi
Xi
2
13
22
0.69022 0.30978
0.15861 3.09104
0.49028 0.02516
14
22
0.74457 0.25543
0.31100 3.09104
0.96131 0.09672
15
23
0.79891 0.20109
0.47251 3.13549
1.48156 0.22327
16
33
0.85326 0.14674
0.65186 3.49651
2.27922 0.42492
17
33
0.90761 0.09239
0.86782 3.49651
3.03435 0.75312
18
44
0.96196 0.03804
1.18449 3.78419
4.48234 1.40302
Total 375 9
9
-9.75224 52.93835 -19.71694 28.33229 Sumber : Pengolahan Data
-
-
571069 ,
2 388943
, 1
1
= =
=
β β
β b
-
-
388943 ,
75224 ,
9 33229
, 28
18 93835
, 52
75224 ,
9 71694
, 19
18
2 2
2
= −
− −
− −
= −
− =
∑ ∑
∑ ∑ ∑
b b
X X
n Y
X Y
X n
b
i i
i i
i i
3,151746 18
9,75224 -
x 0,388943
93835 ,
52
= −
= −
=
∑ ∑
a a
n X
b Y
a
i i
37684 ,
23 151746
, 3
exp exp
= =
= a
α
Universitas Sumatera Utara
7568 ,
20 889
, 37684
, 23
38894 ,
1 37684
, 23
571069 ,
2 1
1 37684
, 23
1 1
= =
+ Γ
=
+ Γ
=
+ Γ
=
x MTTF
β α
Perhitungan MTTF komponen Screen 695-1120-3D-Ø 6 mm dengan bantuan software dapat dilihat sebagai berikut:
Distribution Analysis:
Screen 695-1120-3D-Ø 6 mm
Censoring Information Count Uncensored value 18
Estimation Method: Least Squares failure timeX on rankY Distribution: Weibull
Parameter Estimates Standard 95.0 Normal CI
Parameter Estimate Error Lower Upper Shape 2.57107 0.435116 1.84527 3.58234
Scale 23.3768 2.26473 19.3340 28.2650 Log-Likelihood = -64.003
Goodness-of-Fit Anderson-Darling adjusted = 1.566
Correlation Coefficient = 0.948 Characteristics of Distribution
Standard 95.0 Normal CI Estimate Error Lower Upper
MeanMTTF 20.7568 2.04744 17.1080 25.1839 Standard Deviation 8.66189 1.25737 6.51705 11.5126
Median 20.2710 2.18185 16.4156 25.0319 First QuartileQ1 14.3990 2.11667 10.7946 19.2070
Third QuartileQ3 26.5436 2.43369 22.1777 31.7690 Interquartile RangeIQR 12.1445 1.73956 9.17185 16.0807
Universitas Sumatera Utara
Maka diperoleh nilai MTTF komponen Screen 695-1120-3D-Ø 6 mm sebesar 20,7568.
Perolehan nilai MTTF pada komponen Beater PCD 80 mm 50x6x150 - Ø 17 mm, Beater PCD 80 mm 50x150x50 - Ø 17 mm dan Screen 695-1120-
3D-Ø 6 mm dapat dilihat pada Tabel 5.33.
Tabel 5.33. Perolehan Nilai MTTF Tiap Komponen Komponen
Nilai MTTF hari
Beater PCD 80 mm 50x6x150 - Ø 17 mm 18,7122
Beater PCD 80 mm 50x150x50 - Ø 17 mm 43,4791
Screen 695-1120-3D-Ø 6 mm 20,7568
Sumber : Pengolahan Data
5.2.3. Perhitungan Nilai Konsep Keandalan
