1 Introduction
2 Methodology
2.1 Introducing new parameters for intelligent selective disassembly planning
2.1.1 Disassembly handling index
A. Component size One of the following: | C. Component shape One of the following: | ||
Easily grasped | 2 | Light and symmetric | 0.8 |
Moderately difficult to grasp | 3.5 | Light and semi-symmetric | 1.2 |
Difficult to grasp | 4 | Light and asymmetric | 1.4 |
B. Component weight One of the following: | Moderately heavy, symmetric | 2 | |
Moderately heavy, semi-symmetric | 2.2 | ||
Moderately heavy, asymmetric | 2.4 | ||
Light (< 7.5 lb) | 2 | Heavy and symmetric | 4.4 |
Moderately heavy (< 17.5 lb) | 2.5 | Heavy and semi-symmetric | 4.6 |
Very heavy (< 27.5 lb) | 3 | Heavy and asymmetric | 5 |
2.1.2 Disassembly operation index
A. Disassembly force One of the following: | C. Accessibility One of the following: | ||||
Push/pull operations with hand, straight line motion without exertion of pressure | Little effort required | 0.5 | Dimensions | Shallow and broad fastener recesses | 1 |
Moderate effort required | 1 | Deep and narrow fastener recesses | 1.6 | ||
Large amount of effort required | 3 | Very deep and very narrow fastener recesses | 2 | ||
Twisting and push/pull operations with hand, straight line and twisting motion without pressure | Little effort required | 1 | Location | On plane surface | 1 |
Moderate effort required | 2 | On angular surface | 1.6 | ||
Large amount of effort required | 4 | In a slot | 2 | ||
Inter-surface friction and/or wedging, Straight line motion with exertion of pressure | Little effort required | 2.5 | D. Positioning One of the following | ||
Moderate effort required | 3 | Level of accuracy required to position the tool- Symmetry | No accuracy required | 1.2 | |
Large amount of effort required | 5 | Some accuracy required | 2 | ||
Inter-surface friction and/or wedging, Straight line and twisting motions with exertion of pressure | Little effort required | 3 | High accuracy required | 5 | |
Moderate effort required | 3.5 | Level of accuracy required to position the tool-Asymmetry | No accuracy required | 1.6 | |
Large amount of effort required | 5.5 | Some accuracy required | 2.5 | ||
Material stiffness, Twisting motions with pressure exertion | Little effort required | 3 | High accuracy required | 5.5 | |
Moderate effort required | 4.5 | ||||
Large amount of effort required | 6.5 | ||||
B. Requirement of tools for disassembly One of the following | |||||
Exertion of force | No tools required | 1 | Exertion of torque | No tools required | 1 |
Common tools required | 2 | Common tools required | 2 | ||
Specialised tools required | 3 | Specialised tools required | 3 |
2.1.3 Disassembly demand index
2.1.4 Disassembly cost index
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Operation time:
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Tool change:
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Disposal cost:
2.2 Improved genetic algorithm optimisation
2.2.1 Disassembly representation using a hybrid graph model
2.2.2 Disassembly feasibility and constraint matrices
2.2.3 GA parameters and operators
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Chromosome representation
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Objective function
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Initial population
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Chromosome selection
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Crossover
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Crossover operator:
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Mutation
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Termination conditions
3 Case study and performance analysis
3.1 Case study 1: turbocharger
3.1.1 Background
Number | Component | Disassembly task | Disassembly tool | Reusable | Disassembly point (x,y,z) (mm) | Mass (g) | Demand |
---|---|---|---|---|---|---|---|
1 | Nut | Unscrewing | Spanner | No | (175, 75, 0) | 4 | Low |
2 | Bolt 1 | Unscrewing | Spanner | No | (50, 100, 100) | 7.5 | Low |
3 | Bolt 2 | Unscrewing | Spanner | No | (50, 30, 100) | 7.5 | Low |
4 | Bolt 3 | Unscrewing | Spanner | No | (100, 30, 100) | 7.5 | Low |
5 | Bolt 4 | Unscrewing | Spanner | No | (100, 100, 100) | 7.5 | Low |
6 | Turbine housing | Removing | Hammer | Yes | (80, 80, 105) | 1770 | Very high |
7 | Cartridge | Removing | Hammer | Yes | (80, 80, 70) | 1174 | High |
8 | Bolt 5 | Unscrewing | Spanner | No | (60, 60, 50) | 5 | Low |
9 | Bolt 6 | Unscrewing | Spanner | No | (65, 70, 50) | 5 | Low |
10 | Bolt 7 | Unscrewing | Spanner | No | (70, 65, 50) | 5 | Low |
11 | Compressor housing | Removing | No tool | Yes | (80, 80, 50) | 480 | Very high |
12 | Electronic actuator | Removing | No tool | Yes | (140, 50, 105) | 260 | Medium |
3.1.2 Performance analysis
Number | Component | Disassembly handling analysis | Disassembly operation analysis | Demand | |||||
---|---|---|---|---|---|---|---|---|---|
Size | Weight | Shape | Force | Tools requirement | Accessibility | Positioning | |||
1 | Nut | 2 | 2 | 0.8 | 4 | 2 | 1 | 2 | 5 |
2 | Bolt 1 | 2 | 2 | 0.8 | 4 | 2 | 1 | 2 | 5 |
3 | Bolt 2 | 2 | 2 | 0.8 | 4 | 2 | 1 | 2 | 5 |
4 | Bolt 3 | 2 | 2 | 0.8 | 4 | 2 | 1 | 2 | 5 |
5 | Bolt 4 | 2 | 2 | 0.8 | 4 | 2 | 1 | 2 | 5 |
6 | Turbine housing | 4 | 2 | 1.4 | 1 | 3 | 1 | 1.2 | 0 |
7 | Cartridge | 3.5 | 2 | 1.2 | 3 | 3 | 1.6 | 1.2 | 1 |
8 | Bolt 5 | 2 | 2 | 0.8 | 4 | 2 | 2 | 5 | 5 |
9 | Bolt 6 | 2 | 2 | 0.8 | 4 | 2 | 2 | 5 | 5 |
10 | Bolt 7 | 2 | 2 | 0.8 | 4 | 2 | 2 | 5 | 5 |
11 | Compressor housing | 3.5 | 2 | 1.2 | 1 | 3 | 1 | 1.2 | 0 |
12 | Electronic actuator | 2 | 2 | 1.2 | 1 | 3 | 1 | 1.2 | 3 |
Optimum solution | F(ch,gn) |
---|---|
1 4 5 12 2 3 6 8 9 10 7 11 | 1362.0333 |
Optimum solution | F(ch,gn) |
---|---|
8 9 10 4 3 5 2 1 6 12 11 7 | 1372.0333 |
Disassembly operations and process times based on the proposed method | Disassembly operations and process times based onthe conventional method | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Disassembled part | Trial 1 (s) | Trial 2 (s) | Trial 3 (s) | Trial 4 (s) | Trial 5 (s) | Mean time(s) | Disassembled part | Trial 1 (s) | Trial 2 (s) | Trial 3 (s) | Trial 4 (s) | Trial 5 (s) | Mean time(s) |
1-Nut | 8 | 8 | 7 | 9 | 7 | 7.8 | 8-Bolt 5 | 26 | 25 | 30 | 24 | 26 | 26.2 |
4-Bolt 3 | 20 | 17 | 18 | 21 | 22 | 19.6 | 9-Bolt 6 | 24 | 22 | 26 | 26 | 23 | 24.2 |
5-Bolt 4 | 22 | 27 | 25 | 24 | 20 | 23.6 | 10-Bolt 7 | 26 | 22 | 21 | 30 | 28 | 25.4 |
12-Electric Actu. | 7 | 5 | 5 | 8 | 8 | 6.6 | 4-Bolt 3 | 24 | 30 | 29 | 20 | 21 | 24.8 |
2-Bolt 1 | 20 | 26 | 23 | 22 | 23 | 22.8 | 3-Bolt 2 | 22 | 23 | 25 | 20 | 25 | 23 |
3-Bolt 2 | 24 | 20 | 22 | 23 | 19 | 21.6 | 5-Bolt 4 | 28 | 28 | 35 | 35 | 25 | 30.2 |
6-Turbine hous. | 10 | 9 | 8 | 11 | 8 | 9.2 | 2-Bolt 1 | 23 | 20 | 23 | 26 | 24 | 23.2 |
8-Bolt 5 | 20 | 21 | 23 | 25 | 20 | 21.8 | 1-Nut | 8 | 8 | 7 | 7 | 9 | 7.8 |
9-Bolt 6 | 22 | 18 | 22 | 25 | 20 | 21.4 | 6-Turbine hous. | 10 | 11 | 11 | 10 | 9 | 10.2 |
10-Bolt 7 | 23 | 19 | 24 | 26 | 27 | 23.8 | 12-Electric Actu. | 7 | 5 | 9 | 7 | 8 | 7.2 |
7-Cartridge | 5 | 6 | 7 | 6 | 8 | 6.4 | 11-Comp. Hous. | 9 | 10 | 9 | 10 | 11 | 9.8 |
11-Comp. Hous. | 9 | 7 | 8 | 9 | 8 | 8.2 | 7-Cartridge | 7 | 8 | 8 | 5 | 6 | 6.8 |
Total process time (s) | 190 | 183 | 192 | 209 | 190 | 192.8 | Total process time (s) | 214 | 212 | 233 | 220 | 215 | 218.8 |
3.2 Case study 2: water pump
Number | Component | Disassembly task | Disassembly tool | Reusable | Disassembly point (x,y,z) (mm) | Mass (g) | Demand |
---|---|---|---|---|---|---|---|
1 | Crankcase cover | Removing | Manual | Yes | (40, 40, 45) | 1021 | Very high |
2 | Crankcase | Removing | Manual press | Yes | (23, 23, 5) | 129 | Medium |
3 | Bearings and shaft | Pulling out | Manual press | Yes | (30, 30, 45) | 152 | High |
4 | Spring chamber | Removing | Manual press | No | (35, 35, 900) | 16 | Medium |
5 | Spring | Removing | Manual | No | (30, 30, 90) | 9 | Low |
6 | Ring | Pulling out | Manual | No | (35, 35, 95) | 35 | Medium |
7 | Rotor | Pulling out | Manual press | Yes | (50, 50, 100) | 250 | Very high |
Number | Component | Disassembly handling analysis | Disassembly operation analysis | Demand | |||||
---|---|---|---|---|---|---|---|---|---|
Size | Weight | Shape | Force | Tools requirement | Accessibility | Positioning | |||
1 | Crankcase cover | 2 | 2 | 0.8 | 0.5 | 1 | 1 | 1.2 | 0 |
2 | Crankcase | 2 | 2 | 1.2 | 3 | 3 | 1 | 1.2 | 3 |
3 | Bearings and shaft | 2 | 2 | 0.8 | 3 | 3 | 2 | 2 | 1 |
4 | Spring chamber | 2 | 2 | 0.8 | 3 | 1 | 2 | 1.2 | 3 |
5 | Spring | 3.5 | 2 | 1.2 | 1 | 1 | 2 | 2 | 3 |
6 | Ring | 2 | 2 | 0.8 | 0.5 | 1 | 2 | 1.2 | 3 |
7 | Rotor | 2 | 2 | 0.8 | 3 | 3 | 1 | 2 | 0 |
Optimum solution | F(ch,gn) |
---|---|
2 1 7 6 3 5 4 | 34.65 |
Optimum solution | F(ch,gn) |
---|---|
2 1 7 3 6 4 5 | 42.22 |
Disassembly operations and process times based on the proposed method | Disassembly operations and process times based on the conventional method | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Disassembled part | Trial 1 (s) | Trial 2 (s) | Trial 3 (s) | Trial 4 (s) | Trial 5 (s) | Mean time(s) | Disassembled part | Trial 1 (s) | Trial 2 (s) | Trial 3 (s) | Trial 4 (s) | Trial 5 (s) | Mean time(s) |
2-Crankcase | 18 | 19 | 20 | 17 | 17 | 18.2 | 2-Crankcase | 18 | 18 | 16 | 20 | 17 | 17.8 |
1-Crankcase cover | 5 | 5 | 6 | 6 | 4 | 5.2 | 1-Crankcase cover | 4 | 5 | 6 | 5 | 6 | 5.2 |
7-Rotor | 15 | 14 | 16 | 17 | 14 | 15.2 | 7-Rotor | 12 | 15 | 17 | 16 | 15 | 15 |
6- Ring | 5 | 4 | 4 | 5 | 7 | 5 | 3-Bearings and shaft | 14 | 14 | 13 | 15 | 14 | 14 |
3-Bearings and shaft | 11 | 13 | 12 | 11 | 9 | 11.2 | 6- Ring | 8 | 8 | 10 | 7 | 7 | 8 |
5-Spring | 8 | 8 | 7 | 8 | 7 | 7.6 | 5-Spring | 8 | 9 | 10 | 7 | 10 | 8.8 |
4-Spring chamber | 10 | 12 | 12 | 10 | 9 | 10.6 | 4-Spring chamber | 12 | 12 | 11 | 11 | 14 | 12 |
Total process time (s) | 72 | 75 | 77 | 74 | 67 | 73 | Total process time (s) | 76 | 81 | 83 | 81 | 83 | 80.8 |