The tact time is determined by the slowest machine in the line. In your case it is 4.5 min. This is the time from the board leaving the output conveyor sensor to the next board leaving the sensor. The first machine, which finishes the job in 3 min. has to wait 1.5 min. to put its finished board onto the conveyor, because all boards will back up to the first machine. In practice, this time is even longer, because all other machines in line will impact the time of the first machine. If the line is that badly un-balanced, at least the last machine should be set up to be the fastest and the first the slowest. Even when the line is well balanced, you may want to calculate 10 % slower with each machine you are adding in line.
Station A does 8,000 comp/h, station B 8,000 � 800 = 7,200 comp/h, station C 7200 � 720 = 6,480 comp/h...
Replenishment time is dependent on the type of machine you are using. Can you re-fill, while the machine is running? Are you using stick magazines? Do you have extra feeders, which you could prepare with new components. Are you using full reels or do you get only a few inches long tape? Do you have only one operator and two feeder table sides on a 100 feet long line? However, 20% re-fill time is too high.
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