TUGAS 6 SOAL
Perakitan peralatan elektronik, perusahaan tersebut ingin membuat chart untuk mengendalikan tingkat ketelitian.
Ada 40 pengukuran kekerasan yang diperoleh dari 10 samples masing-masing 4 komponen. (n=4) diukur setiap sample seperti tabel. Control limit standar deviasi dengan k = 5.
Sample number j (j=1 …10)
Accuracy of unit Xi
(I=1, … 4) Sample average X
1 5, 10, 20, 30 16,25
2 10 , 8, 12, 18, 40 17,6
3 1, 22, 25, 33, 34 23
4 4, 14, 10, 16, 38 16,4
5 7, 17, 22, 24, 37 21,4
6 3, 10, 19, 29, 39 20
7 8 , 25, 28, 31, 36 25,6
8 6, 7, 25, 10, 34 16,4
9 9, 12, 21, 26, 31 19,8
10 2, 11, 17, 22, 10 12,4
Tentukanlah Upper Control Limits (UCL), Lower Control Limit (LCL) dan gambar grafik control chartnya.
Jawab : Rata-rata
X
=16,25+17,6+23+16,4+21,4+20+25,6+16,4+19,8+12,4 10
X
= 18,88Standar Deviasi S
X
=√
(16,25−18,88)2+(17,6−18,88)2+(23−18,88)2+(16,4−18,88)2+(21,4−18,88)2+(20−18,88)2+(25,6−18,88)2+(16,4−18,88)2+(19,8−18,88)2+(12,4−18,88)2 10−1S
X
=√ 6 , 91 +1 , 63+16 , 97+6 , 15 +6 , 35+1 9 , 25 +45 , 15 +6 ,15 +0 , 84 +41 , 99
S
X
=√ 14 , 82
= 3,84UCL =
X
+ k SX
= 18,88 + 5(3,84) = 38.08LCL =
X
- k S
X
=
0 2 4 6 8 10 12
0 2 4 6 8 10 12
Grafik Control Chart
Sample Number
Range of Sample
18,88 - 5(3,84) = -0,32
