Question

The total cycle time of an automatied fiber placement (AFP) operation (sheet lamination), used to manufacture a section of the airplane fuselage, is 8 hours and 40 minutes. The setup time before the start of the operation is 10 minutes. After each layer is put down, an inspection stage is performed for 5 minutes. The AFP head requires cleaning cycle of 3 minutes every 7 layers.

a. If the part is made of 20 layers, what is the time required (in minutes) to lay down 1 layer?

b. What is the percentage of down time for this operation?

c. What is the total cycle time (in minutes) for making this part, if the lay down speed was doubled?

Answer 1

Assumption: It is assumed that cleaning is not performed at end (i.e. end of 20th cycle ) this is because only 6 layers are deposited after last cleaning and cleaning is required after every 7 layers.

Total Cycle time for AFP operation = 8 Hours40 minutes = 520 minutes.

Setup time before start = 10 minutes

Inspection time after each layer = 5 minnutes

Every 7 layer, cleaning time = 3 minutes.

No. of times cleaning required for 20 layers = 2.

a)

Total Extra time = Setup time + inspection time + Cleaning time

= 10 + 5*20 + 2*3

= 116 minutes

Time for laying down 20 layers = 520-116 = 404 minutes.

Time for laying down single layer = 404/20 = 20.2 minutes = 20 minutes 12 seconds.

b) Percentage of downtime = downtime/ total time * 100

= 116/520 *100

= 22.3 %.

c) Cycle time if lay down speed was doubled = down time + (lay down time / 2)

= 116 + (404/2)

= 318 minutes.