Rob and Patty balance the line.....
Patty and Rob went to balance the line. They found that this very complex board had 1167 passives, 24 simple ICs (SICs) and 9 complex ICs. Currently the chip shooter (CS) is placing all of the passives and 9 of the SICs. The flexible placer (FP) is placing the 9 complex ICs and 15 SICs. The placement rate for the chip shooter is 60K/hr for passives and 3K/hr for SICs. The CS cannot place CICs. The FP places complex ICs at 4K/hr and passives and SICs at 8K/hr.
To balance a line, Rob and Patty start by seeing how long it will take the CS to place all of the passives and the FP to place all of the SICs and CICs.
For the CS to place all of the passives: timeCS = 1167 passives/60K passives/hr = 0.01945 hrs = 70.02 seconds.
The time FP takes to place all fo the SICs and CICs is: timeFP = 24 SICs/8K SICs/hr + 9 CICs/4K CICs/hr = 0.003 hrs + 0.00225 hrs = 18.1 seconds
Since the FP is waiting for the CS, Patty and Rob should move passives to the FP. They will determine the number of passives, x, to move to the FP by setting the CS and FP times equal:
tCS = (1167-x) passives/60K passives/hr x passives/8K/hr + 18.1 secs/3600 sec/hour
Solving for x:
(1167-x)/60,000 = x/8,000 +18.1/3600
1167 – x = 7.5 x + 301.667
8.5 x = 865.333
x = 101.8 = 101 go to FP (the reason Patty and Rob round down to 101 is due to the much faster placement speed for the CS)
So Patty and Rob moved to 101 passives to the flexible placer. Each machine's time should be about the same now. They performed the following calculation to check their results:
tCS = (1167-101)/60,000 = 0.017767 hrs = 63.96 seconds
tFP 18.1/3600 + 133/8000 = 0.017653 hrs = 63.55 seconds
Patty and Rob then went to the line to physically move the passive feeders to the FP. They then measured the placement time of the both the CS and FP and found them to be 65.2 and 64.9 seconds respectively, quite close to their calculations.
A meeting was held to discuss the results and the tremendous productivity improvement (81 vs 65.2 second cycle time, an 81/65.2 = 1.242 => 24.2 % improvement.) Everyone at AJAX was pleased (maybe not Charlie!) and felt the experience was one of great learning. At the end of the meeting Patty and Rob had a brief chat.
"Patty, I really appreciate all of your help," said Rob said thankfully.
"Don't forget The Professor. I don't think I could have handled Charlie without him," responded Patty.
"Anyway,to show my gratitude, will you allow me to take you to dinner?" asked Rob.