Question

3. The operation manager of a body and paint shop has five cars to schedule for repair. He would like to minimize throughput time to complete all work on these cars. Each car requires body work prior to painting. The estimates of the times required to do the body and paint work on each are listed below. Paint (Hours) 6 Car A B C D E Body Work (Hours) 12 7 9 4 10 4 3 12 in (a) Determine the job sequence using the Johnson rule. (b) How much idle time is related to painting? (use a chart to find out the idle time for painting).

Answer 1

Using Johnson's Rule as: 1) Select the job with the mininum processing time (either in operation 1 or 2) 2) It the minimum time belongs to operation ! schedule it at first, else schedule it at last. 3 ) OY Remove that job from the list of jobs left, repeat the above steps for the remaining jobs by scheduling them first or last in between the ljobs. Using given data :- Body Paint previously scheduled Job work A 12 6 ☺ B Y ② x c 9 10 s 3 9 Ох E 12 5 ③ x e c A - ESB

a) ay Job Sequence 1 2 3 A 4 E 5 B b) Cantt chart is shown below:- 03 12 24 36 43 CA E B Body work С. А ADU لوا B Paint 7 12 22 24 30 36 41 43 47 ç 2 6 Idle time for paint 3+5+2+6+2= 18 hrs