In one of their plants they made printed circuit boards (PC’s), which were used by other plants In the company In a variety of computer products. The basic process runs 3 shifts per day and it can be briefly depicted by following flow diagram The targeted output for the plant is 3000 boards per day, five days a week, with plant running three shifts per day. But the plant has been failed to reach and maintain the targeted throughput at a steady rate due to manufacturing complexities associated with the product mix.
It was also found that, the output of the pro-coat process Is very slow (1200 boards/day) compared to the expected throughput and therefore Hal has to engage a vendor on the pro- coat process to fulfill the demand. This engagement of vendor has caused increase in cost per board and two days delay because of shipping up and back. So the Hal is striving to increase the throughput of the pro-coat process and the purpose of this case study is to provide some guidance to them In their effort by Glenn some recommendations to Improve the existing system. Working hours = 24- (Breaks + Lunch + shift change + Meeting) = 24-(XIX+XX+1 OX+90/5) 19. Hrs Demand = 3000/(19. XX) = 2. 604 boards/min Assumption; 1. Demand = Arrival rate 0 2. Arrival pattern exponentially distributed 0 Machine Name Mean process (load) time (min) SST. Dive. Process Time (min) Trip Time (conveyor) (min) MATT (her) METRO (her) Setup time (min) Availability Number of machines Rate per day Clean 0. 33 15 4 0. 95238 3325 coat 2 Expose 103 67 300 10 0. 96774 2834 Develop 2. 67 0. 99010 3456 Inspect 0. 5 1 . Ooh 2 Bake 3 161 8 3435 Touch 9 7680 once Assumption: Inspection and MI are manual operations. So we can add number of work stations such that those are not bottleneck. Cleaning Effective processing time 0 ? = 0. 33/0. 95238 = 0. 3465 mint Utilization (u) = 2. 604 x 0. 3465 = 0. 902 Departure rate; = 27. 019 2. Coat 1 Similarly, Effective processing time 0 utilization = 0. 902 3. Coat 2 4. Coating and expose Since the coating 2 processing rate greater than the arrival rate of the pro- coat system. Arrival rate of the expose machine govern by the arrival rate of pro-coat system Expose machine calculations based on Jobs (60 boards = 1 Job) Arrival rate =2. 604/60 =0. 0434 Jobs/min Buffer size = 05 Blocking size = (buffer size + maximum Jobs in expose machines) 10 = 103/0. 677 = 106. 43 mint Assumption; Number of boards between setups = 120 Total effective processing time (Preemptive and Non-preemptive outages); 0 – = 114. 14 min Standard deviation for repair = O min (constant distribution) Preemptive outage variance = = 6856. 43 Preemptive outage variation -0. 6052 As: No variation in setups (constant distribution) Total variance (preemptive + non-preemptive outage) = =6858. 29 C.V. for expose(preemptive + non-preemptive outage) = expose = 99 Arrival C.V. for batch = 0. 546 = 0. 526 Utilization for = Arrival C.V. for individual part/batch size