Exercise and answer for factory physics course, Exercises of Manufacturing Processes

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Thomas De Meulenaer As2024-2984 Exercises Factory Physics Chapter 2 Exercise 1: Effective process times The mean time to expose a single panel in a circuit-board plant is 3 minutes with a standard deviation of 1,75 minutes. 1. If process times are i.i.d. (Independent and identically distributed), what will be the mean and variance of a job of 50 panels? What will be the coefficient of variation of the 50-panel job? lay = N- = S0- Qanta= ASO-min 2 2 2 2 Ton = Nos So-AWS = 452,725 mb Coz Yon _ YASS, 425° = 008 25 oN ASO Now suppose times to failure on the expose machine are exponentially distributed with a mean of 60 hours and the repair time is also exponentially distributed with a mean of 1,5 hours. What are the effective mean and CV of the process time for a job of 50 panels? mga ere + a _ go = 0,54 56 Ma= A> LX Me — 62* AS k; _ Ao min . =-—~5 = AS53, 45M te No aae Ge Cot Ct ca )A(A- A) GS Fre = 71 = 5 Sorin 0, 0825 4 (A +4): ©, 9t56- on 0,4756) - ink, = 0,0353F —> Cet 0, 78804 What are the effective mean and CV of the process time for a job of 50 panels, if machine failures only happen between jobs and never during actual processing? he ASR Som w= b= Jomw N,= b0-60 = 24 ASO kK. = 2. 4 = A953, FM = fet We + z 2 _ 2 we + By Netty Mo Ma 2 - Jo QU-A. = 15 oot Jo AS3,A vo m Tht = RAu, 0625 min ys cee Se VOW. onase fe AT3, FT