Question

A bike frame has to go through the welding operation. The time in the welding operation is spent as follows: 2 hours waiting in front of the cutting machine for the batch to start, 0.5 hour waiting for the setup of the machine, 2 hours waiting for the other pieces of the batch to go through cutting, 1 minute at the cutting machine, and 1.5 hours waiting for the transfer to the welding machine; then, at the welding machine, the unit spends 2 hours waiting in front of the welding machine for the batch to start, 0.5 hour waiting for the setup of the welding machine, 2 hours waiting for the other pieces of the batch to go through welding, 1 minute at the welding machine, and 1 hour waiting for the transfer to the next department.

(a)[6] Calculate the exact total flow time in minutes of the welding operation.

(b)[2] Calculate the exact value added time in minutes of the welding operation.  

(c)[2] Calculate the value added percentage (percentage, 5 decimals, i.e. 1.54397%).

Answer 1

Given,

Wait time before start =2 hrs

Setup time= 0.5 hrs

Wait time for other pieces to go through cutting= 2 hrs

Cutting time= 1 min = 1/60 hr =0.0166 hr

Transfer to welding wait time= 1.5 hrs

Welding wait time= 2 hrs

Welding setup time= 0.5 hrs

Wait for other pieces to go through welding= 2 hrs

Welding time= 1/60 hr = 0.0166 hr

Wait for transfer to next dept. = 1 hr

a) Exact flow time = wait time before start + setup time + wait time for other pieces to go through cutting + cutting time + transfer wait time + welding wait time + welding setup + wait for other pieces to go through welding + welding time + wait for transfer = 2+0.5+2+0.0166+1.5+2+0.5+2+0.0166+1 = 11.5332 hrs

b) Exact value added time = 1+ 1 = 2 mins = 2/60 hrs = 0.033 hr

c) value added percentage = (0.03333/11.5332) * 100 = 0.28899%