Question

Discuss and illustrate four rules that could be used to design a product for assembly [8 marks] Table Q itemises the precedence and timing information that is required to complete the assembly of a product. Through the application of a Largest Candidate Rule procedure, devise an assembly task grouping to achieve an assembly rate of 40 per hour. What is the utilisation for each assembly station [8 marks] If the assembly rate is increased to 60 per hour, discuss the implications for station task assignment in terms of the minimum number of stations required. [4 marks] Task Precedence Duration (s) 1 30 2 20 10 20 4 5 4 40 6 3 50 7 40 6 2.5 8,7 20 8 9 30 Table Q1 Assembly Task List For the assembly rate of 40 per hour, devise an inter station layout to accommodate the assembly rate and justify any assumptions that you make. How will this lay out be affected by increasing the assembly rate to 60 per hour. [5 Marks

Answer 1

Available time seconds 3,600 Desired output units 40 Optimum Cycle time =Available Time/Desired output rate seconds 06 Total Task Time seconds 260 rounded up Minimum #of stations neede Total Task time /Cycle Time Draw Precedence diagram 2 5 4 >7 Assignment of tasks to workstations as per most following task rule Preceden Work-Eligible TaskAssigned Task Cumulative Idle Time Task (seconds) Task station Time Time Time ce 1 30 1 1,3 1 30 30 2. 20 1 2,3 2 20 50 10 3 3 10 60 4,6 4 20 3 4 20 80 10 5 40 4 2 5,6 6 50 50 5,7 6 50 5 40 90 7 40 6 3 7,8 7 40 40 8 20 2,5 8 20 60 30 7,8 9 30 90 Total Idle Time = Total 260 End 10 Cycle time Proposed # of w/s Idle Time per cycle (seconds) Lead time (seconds) 90 3 seconds 10 = Cycle Time x number of stations 260/270 Total Task Time / Lead Time 270 Efficiency of assembly line 96.3% CO aY III