#8_STOPWATCH TIME STUDY ANALISA DAN PENGUKURAN KERJA

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1 #8_STOPWATCH TIME STUDY ANALISA DAN PENGUKURAN KERJA
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2 LANGKAH – LANGKAH PENGUKURAN [WAKTU] KERJA

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6 Membagi operasi dalam elemen-elemen
Purpose : easy to measure & line balancing Separate handling time (non-productive time) with operation time (productive time) Separate constant element with variable element. Every element must have an easily identifiable starting and ending point (breakpoints) Continuities between elements Elements times: 0.04min (short), 0.25min (reasonable)

7 Metode Stopwatch Time Study
CONTINUOUS TIMING Tombol stop-watch ditekan pada saat awal elemen kerja dan terus dibiarkan berjalan selama periode studi. Pengamat terus melihat jalannya jarum stop-watch dan setiap awal/akhir dari sebuah elemen kerja yang ada mencatat dan menuliskannya di lembar pengamatan. Waktu setiap elemen kerja akan diperoleh dengan cara “pengurangan” dan dilakukan setelah studi pengukuran kerja selesai dilaksanakan. APA KEKURANGAN-NYA??? REPETITIVE (SNAP-BACK METHOD) Jarum penunjuk stop-watch selalu dikembalikan ke posisi nol setiap kali satu elemen kegiatan selesai dilaksanakan. Waktu yang diamati dan dicatat akan merupakan waktu yang sebenarnya. Time study analyst akan bisa mendeteksi dengan mudah adanya variasi perbedaan waktu dari setiap elemen kegiatan. APA KEKURANGAN-NYA??? ACCUMULATIVE TIMING Merupakan kombinasi cara pengukuran dengan metoda continuous dan snap-back (pengukuran dilaksanakan dengan menggunakan dua atau lebih stop-watch yang bekerja secara bergantian).

8 THE RULES !!! Don’t comment to the worker during the task
Stand (don’t sit) beside the worker Write every event (even though it may seems not important) Have a good position to observe Stop the study if the worker seems to be under pressure and it affects his/her work

9 PENGAMATAN!!!!

10 Tes Kenormalan, Tes Keseragaman, Tes Kecukupan Data
TES KENORMALAN  data pengamatan seharusnya berjumlah cukup besar (banyak) dan berdistribusi normal. TES KESERAGAMAN  data harus homogen dan diperoleh dari populasi yang sama. TES KECUKUPAN  data yang dikumpulkan telah cukup secara obyektif, dengan konsep statistik (derajat ketelitian dan tingkat keyakinan/kepercayaan yang diinginkan).

11 Determining Number of Cycles
Time measurement Measuring time of each element The number of observation of each element depends on the significance level and required level of accuracy

12 Number of Cycles To determine sample size: zs eT n = where
2 where z = number of standard deviations from the mean in a normal distribution reflecting a level of statistical confidence T = average job cycle time from the sample time study e = degree of error from true mean of distribution s = = sample standard deviation from sample time study S(xi - x)2 n - 1

13 Number of Cycles : Example
Average cycle time = 0.361 Computed standard deviation = 0.03 Company wants to be 95% confident that computed time is within 5% of true average time n = = = or 11 zs eT 2 (1.96)(0.03) (0.05)(0.361)

14 Rumus Uji Kecukupan Data
Keterangan: N’ = Jumlah pengamatan untuk elemen kerja yang diukur k = tingkat keyakinan s = tingkat ketelitian

15 Recommended number of cycles/observations

16 Performance Rating & Waktu Normal
1) Waktu Pengamatan (Tobs) 2) TN < TObs untuk p < 1 (100%) 3) TN = TObs untuk p = 1 (100%) 4) TN > TObs untuk p > 1 (100%) Normal time : Tn = Tobs (PR)

17 WESTINGHOUSE RATING SYSTEM

18 Menentukan Allowance (personal time, fatigue, delays)
Constant Personal Needs Fatigue Special Avoidable Delays Unavoidable Delays More details in : Handbook of IE (Salvendy) : pp. 1409

19 Waktu Standar dan Output Standar
Waktu Normal (TN) Allowance Waktu Baku/Standard (TS) TS = TN (1 + Apfd) OS = 1 / TS

20 Let’s Try!

21 Example (a) normal time
Given: A direct time study was taken on a manual work element using the snapback method. The regular cycle consisted of three elements : a, b, and c. Element d is an irregular element performed every five cycles. Determine (a) normal time (b) standard time for the cycle using Apfd = 0.15 Work element a b c d Observed time (min) 0.56 0.25 0.50 1.10 Performance rating 100% 80% 110%

22 Solution (a) Normal time: TN = 0.56(1.00) + 0.25(0.80) + 0.50(1.10)
+ 1.10(1.0)/5 = 1.53 min (b) Standard time: TS = 1.53( ) = 1.76 min

23 WESTINGHOUSE RATING SYSTEM

24 Thank you “Knowing exactly what you want to do,
and then seeing that they do it the best and cheapest way.” - Frederick W. Taylor- Thank you