The time occupied by the item within the cell is known as the throughput time, the time spent in adding value to the item is known as the cycle time. In functional machine layouts there is a considerable difference between these two values, however, in work cells the difference is minor. The cycle time is governed by the slowest operation within the cell. This does not necessarily mean the slowest machine.

Now consider the operation times for each activity within the die casting cell.

Casting ------------------------	60 seconds
Separation -------------------	2 seconds
Machining face -------------	15 seconds
Drilling and tapping -------	20 seconds
Inspection --------------------	10 seconds

The robot servicing this cell has to perform all of the transfer operations within the cycle time of the die casting machine will have to wait until the robot is free before the unloading can continue. This will result in underutilisation of the machine and possibly some process problems could arise. It is necessary to remember that other processes must be accommodated within the 60 second process time of the die casting machine. The available time for work transfer can be worked out by taking the difference between the cycle time of the die casting machine and the sum of the cycle times of the other processes.

Available time for robot is: 60 - (2 + 15 + 20) = 23 seconds

The inspection operation will be carried out using a vision system at the dispatch magazine. This means that components need only be placed in the inspection machine, removal and palletisation will be carried out by the inspection machine.

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