IV. RESULTADOS Y DISCUSIÓN
4.1.2. Análisis de pH y acidez
Toshiba: Producer of the First Notebook Computer Production Processes
Production Process Mapping and Little’s Law How Production Processes Are Organized
Break-Even Analysis
Designing a Production System Project Layout
Workcenters Manufacturing Cell
Assembly Line and Continuous Process Layouts Assembly-Line Design
Splitting Tasks
Flexible and U-Shaped Line Layouts Mixed-Model Line Balancing
Case: Designing Toshiba’s Notebook Computer Line
Overview
This chapter introduces how processes need to be design to match the volume and variety characteristics of the products that a company must produce. A new version of the product-process matrix is the major concept used in this explanation. Notice that this matrix includes manufacturing cells as a major type of processes. Break-even analysis is also covered in the chapter. The design of assembly lines is the major problem covered in the chapter. We give additional coverage of process analysis in chapter 6 – Six-Sigma Quality.
Teaching Tips:
Have the students look at their notebook computers and think about how you would make these. In the case at the end of the chapter, they will study this process.
Remember to stress the idea of cycle time, and balance-delay (idle time) in the design of this system. These concepts are important to the analysis of any system.
If you have the time to take the students on a plant tour, this is a sure winner. Have them categorize the types of processes they see on the tour.
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Case: Designing Toshiba’s Notebook Computer Line - Teaching Note What is the daily capacity of the assembly line designed by the engineers?
.
Required Daily Production 150 Required Cycle Time
Production Hours Each Day 7.5 180
Task Seconds Task Description Station
Original
Configuration Station Idle time
1 100 Lay out principal components on conveyor 1 100 80
2 6 Peel adhesive backing from cover assembly 1 106 74
3 4 Put screws for Opn 8 in foam tray, place on belt 1 110 70
4 50 Scan serial number barcode 2 50 130
5 13 Connect LCD cable-1 to LCD-Printed Circuit Board (PCB) 2 63 117
6 16 Connect LCD cable-1 to LCD display panel 2 79 101
7 13 Connect LCD cable-2 to LCD-PCB 2 92 88
8 16 Screw LCD-PCB into cover assembly 2 108 72
9 6 Put screws for Opns 13, 16 in foam tray on belt 2 114 66
10 26 Install LCD display panel in cover assembly 3 26 154
11 10 Fold and insulate cables 3 36 144
12 13 Install LCD frame in cover assembly 3 49 131
13 23 Screw in frame 3 72 108
14 6 Place PCB-1 in base assembly 3 78 102
15 6 Install CPU bracket on PCB-1 3 84 96
16 13 Screw CPU bracket into base assembly 3 97 83
17 4 Put screws for Opn 23 in foam tray 3 101 79
18 15 Connect ribbon cable to hard disk drive (HDD) 4 15 165
19 11 Connect ribbon cable to PCB-1 4 26 154
20 8 Place insulator sheet on HDD 4 34 146
21 8 Stack PCB-2 on PCB-1 4 42 138
22 8 Stack PCB-3 on PCB-1 4 50 130
23 13 Screw in both PCBs 4 63 117
24 6 Install condenser microphone in holder 4 69 111
25 13 Connect microphone cable to PCB-1 4 82 98
26 8 Tape microphone cable down 4 90 90
27 13 Connect backup battery to PCB-2 and install in base 4 103 77
28 4 Put screws for Opn 31 in foam tray 4 107 73
29 6 Install support frame on base assembly 5 6 174
30 13 Stack PCB-3 on PCB-1 5 19 161
31 6 Screw in PCB-3 5 25 155
32 8 Install Accupoint pointing device pressure sensor 5 33 147
33 11 Connect PCB-5 to PCB-2 and PCB-4 5 44 136
34 6 Set speaker holder on base 5 50 130
35 11 Install speaker holder and connect cable to PCB-2 5 61 119
36 10 Install clock battery on PCB-4 5 71 109
37 10 Tape down speaker and battery cable 5 81 99
38 16 Check voltage of clock batter and backup battery 5 97 83
39 6 Put screws for Opns 44, 46 in foam tray 5 103 77
40 13 Install wrist rest over Accupoint buttons 6 13 167
41 6 Connect LCD cable to PCB-1 6 19 161
42 6 Tape cable down 6 25 155
43 5 Install keyboard support plate to base 6 30 150
44 23 Screw in support plate 6 53 127
45 18 Install keyboard, connect cable and set in base 6 71 109
46 18 Screw in keyboard 6 89 91
47 8 Install keyboard mask 6 97 83
48 10 Place cushion pads on LCD mask 6 107 73
49 18 Place protective seal on LCD display 7 18 162
50 10 Place brand name seal on LCD mask 7 28 152
51 11 Place brand name seal on outside of cover 7 39 141
52 8 Connect cable to DVD drive 7 47 133
53 33 Install DVD on base 7 80 100
54 22 Install cover on DVD 7 102 78
55 6 Put screws for Opns 56, 57 in foam tray 7 108 72
56 58 Turn over machine and put screws in base 8 58 122
57 8 Put in grounding screw 8 66 114
58 8 Install connector protective flap 8 74 106
59 8 Install DVD assembly 8 82 98
60 6 Install battery cover on battery pack 8 88 92
61 5 Install battery cover 8 93 87
62 31 Insert memory card for hardware test and start software 9 31 149 63 208 Software load (does not require operator) 9 100.3333333 79.66666667 64 71 Test DVD, LCD, keyboard, and pointer, remove memory 9 171.3333333 8.666666667
65 5 Place unit on shock test platform 10 5 175
66 75 Perform shock test 10 80 100
67 10 Scan barcodes 10 90 90
68 15 Place unit on rack for burn-in 10 105 75
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From the spreadsheet we see that task 63 has a cycle time that is longer than the required cycle time which is 180 seconds (to produce 150 units). In the case, this is discussed and we see that 3 units are tested in parallel at task 63 and there is essentially no labor associated with the task. Taking this into consideration we see that the cycle time of task 63 is reduced to 102 seconds. So even though the work content is 310 seconds per unit, the cycle time of the 9th station is 102 seconds since that is the time required by the operators. So given this, it appears that the line is capable of producing 150 computers per day.
That 2th station is clearly the bottleneck with a cycle time of 114 seconds. Given this it would be possible to at least theoretically reduce the cycle time to 114 seconds.
The capacity of the line running with a cycle time of 114 seconds would be 7.5(60 x 60)/114 = 236.8 or 236 computers.
2. Running at maximum capacity, what is the efficiency of the line?
Running with a cycle time of 114 seconds the efficiency of the line is Efficiency = work content / (number of stations x cycle time)
Efficiency = (1258-208)/(10 x 114) = .9211 (92 percent)
This assumes that there is only one operator at each station. Note that we have not included the time to run the software check since this is not a manual task.
3. How should the line be redesigned to operate at the target 300 units per day assuming that no overtime will be used? What is the efficiency of your new design?
To get 300 units per day, we need to get the cycle time down to 7.5 x 60 x 60/300 = 90 seconds.
The following is one solution to the problem. Note the problem with task 1 which has a cycle time of 100 seconds. To solve the problem in this solution, I have just run parallel stations here (two workers would be needed). We still have the problem with task 63, and this solution just assumes that we can load 4
11 3 10 1 10 80
56 9 58 1 58 32
57 9 8 1 66 24
58 9 8 1 74 16
59 9 8 1 82 8
60 9 6 1 88 2
61 10 5 1 5 85
62 10 31 1 36 54
63 10 208 4 88 2
64 11 71 1 71 19
65 11 5 1 76 14
66 12 75 1 75 15
67 12 10 1 85 5
68 13 15 1 15 75
The efficiency of this new system is:
Efficiency = (1258-208)/(14 x 90) = .83333 (83 percent)
Here we assume the first station is duplicated, with two workers and the time associated with task 63 is not included.
4. What other issues might Toshihiro consider when bringing the new assembly line up to speed?
There are major issues associated with whether the tasks can be split as shown in this new line. Some engineering might have to be done to design these new workstations. Moving from a cycle time of 3 minutes to 90 seconds is significant. A lot more material would need to be feed to the line with the new configuration. In addition, the added speed might result in a lot of congestion since the extra 4 workers need to be fit in some way. The current line can only accommodate 10 workers.