Case Study

The case study was taken from automotive supplies factory located in Egypt. The line
contains 12 work elements and 10 work stations as shown in the below figure. The total
working hours 7.5 and the daily production is 96 pieces and the time needed for the arrangement of working material and cleaning is 1 hour. Therefore, the total working time is 6.5 hours and cycle time is 4.06 minutes. Time needed to proceed each element is given in the below table. 

 

 The Line as is

 The line starts with station one where one operator does the assembly of the cushion trim with the foam using rings. The assembly time of this station is 1.78 minutes and idle time is 2.28 minutes.
In station 2 the assembly of cushion trim and foam with chassis is done manually by fixing the clips of trim with the chassis. Then the cushion is dried to prevent the forming of wrinkles that deform the shape of the seat. Only one operator works in this station with total time of 1.75 minutes and total idle time of 2.29 minutes.
In station 3, one operator makes the assembly of the back chassis with cushion chassis using 4 bolts. The time taken for this operation is 2.45 minutes with idle time of 1.59 minutes.
In station 4, one operator assembles two inner recliner covers by hand and fix them in the back chassis. Total time for this operation is 2.4 minutes and idle time is 1.64 minutes.
In station five, one operator assembles the outer covers of recliner and the seat belt with the back chassis. Time needed for this station is 2.3 minutes and idle time is 1.74 minutes.             In station 6, one operator assembles the back trim with the back foam using rings. Station time is 1.5 minutes and total idle time is 2.54 minutes
In station 7, 4 operators assemble back trim and foam with back chassis alternatively. Time of this operation is four minutes and idle time is 0.04 minutes.
In station 8, there are two operators one dries the seats while the other degreases the seats from handling traces. Total station time is 1.83 minutes and idle time is 2.21 minutes.
In station 9, the quality inspector makes quality check to be sure that there are no defects in the seat and prevent sending defected products to customers. This station needs 1.5 minutes operation time and 2.54 minutes idle time.
In station 10, last station, only one operator makes the packing of the seat with plastic covers to prevent dusts from reaching to the seats. This station needs 1 minute and 3.04 minutes idle time.

 

 The below table shows that the line efficiency is 48% and smoothing index is 6.76, the line has total work elements time of 19.39 minutes and idle time of 21.01 minutes. The line has 10 working stations and 14 workers.

 

Line to be

After applying, assembly line balancing, The seat can be assembled in 7 stations only instead of 10 stations. Idle time decreases to be 7.49 minutes, cycle time to be 4 minutes and smoothing index to be 3.88. Line efficiency increased to be 69.25% and daily production rate increased to be 98 parts daily.

 

 

 

The idle time is improved by 64.35%, efficiency by 44%, smoothing index by 42.6. Number of stations decreased by 30% and production rate increased by 2%.