Designing an Assembly Line for Reliability

Read this article. It deals with production efficiency and human behavior. Despite advanced technology and automation, systems are still dependent on human interaction. How can the human component enhance performance, and conversely, how does this human interaction contribute to system failure?

The Algorithm

Our proposed two-stage procedure with sequential generation of feasible solution and selection of final solution can be best described by the following algorithm.

1. Calculate the theoretical minimum number of workstations, N_{\min }, following the formula \sum_{i=1}^{K} \frac{\mu_{i}}{C} \leq N_{\min } \leq \sum_{i=1}^{K} \frac{\mu_{i}}{C}+1. Calculate the minimum cycle time, C_{\text {min }}, using the relationship, C_{\min }=\left[\sum_{i=1}^{K} \frac{\mu_{i}}{N_{\min }}+1\right].

2. Set the trial cycle time C_{t} at C_{\min }.

3. Prepare the list of all unvisited tasks - call it List U.

4. Prepare List R from the tasks of List U with no immediate predecessor or whose immediate predecessors have been visited. The tasks of R are ready for selection.

5. Prepare List A from the task of List R having assembly time less than that of cycle time and is allowable for inclusion.

6. Randomly select a task from List A and reset the cycle time as {C_{t} assembly time}.

7. If cycle time is less than the assembly time, then open a new workstation. Reinitialize cycle time to its original value and repeat the above steps until all nodes are visited.

8. After getting the complete distribution of tasks to workstations, calculate R_{A L}, the reliability of the assembly line.

9. After each run, the new reliability value R_{A L} is compared with the previous R_{A L} value. If the new R_{A L} value is greater than the previous value, the new solution is stored as the basis for next comparison.

10. Increase the cycle time by one unit until it crosses C value. If C value is crossed, go to step 12.

11. Repeat step 2 to 10.

12. Check whether all the work elements have been assigned to specified number of work stations. If not, increase the value of N_{min} by 1 and go to step 2.

13. Print the best solution in terms of overall maximum reliability.