Question

1. A manual assembly line is to be designed to make a small consumer product. The work elements, their times, and precedence constraints are given in the table below. The workers will operate the line for 400 min per day and must produce 300 products per day. A mechanized belt, moving at a speed of 1.25 m/min, will transport the products between stations. Because of the variability in the time required to perform the assembly operations, it has been determined that the tolerance time should be 1.5 times the cycle time of the line. (a) Determine the ideal minimum number of workers on the line. (b) Use the Largest Candidate Rule to balance the line. (c) Compute the balance delay for your solution in part (b).

Element	Time Te (min)	Preceded by
1	0.4	-
2	0.7	1
3	0.5	1
4	0.8	2
5	1.0	2,3
6	0.2	3
7	0.3	4
8	0.9	4,9
9	0.3	5,6
10	0.5	7,8

2. Solve Problem 1 using the Kilbridge and Wester method.

3. Solve Problem 1 using Ranked Proportional Weights Method

4. Work content time is 54 min for a product assembled on a manual production line. Each product is built on a base part that is launched onto the beginning of the line each cycle. The line uses an overhead conveyor that moves at 1.2 m/min. There are 27 workstations on the line, one-third of which have two workers; the rest have one worker each. Repositioning time per worker is 9 sec, and uptime efficiency is 95%. (a) What would be the hourly production rate if the line were perfectly balanced? (b) If the actual production rate is 33 units/hr, what is the balance efficiency of the line? (c) To compensate for service time variability, it has been decided that the tolerance time should be 40% greater than the cycle time. To achieve this, what station length should be used on the line? (d) Determine the elapsed time that each base part spends on the production line?

Hint:

(a) Find no. of workers; for perfect balance E_b = 1, find Tc, using uptime efficiency, find R_p

(b) Using actual Rp find balance efficiency

(c) Tolerance time = station length/ conveyor speed, find new station length

(d) Calculate elapsed time

Answer 1