Such production-lines are very efficient, but impose restrictions on the ganging-combinations allowed for production.
In order to feed the punching unit continuously, there are a number of conditions: 1) replicas should be arranged across a stroke and 2) the strokes should have a minimum length. Indeed, the guillotine cutting of the strokes requires some time, as well as the feeding of the stroke cutting machine. One may set for example a minimum stroke length of 12 inches (30cm) for the stroke cutting machine. This only for strokes with the same punchID, so that the punching unit does not require an additional setup.
When a stroke contains 2 different punchID’s, then each part should be at least 12 inches long.
Consider the next example of 4 articles (orders). When they are arranged across in a stroke, they require respectively 6, 6, 3 and 4 replicas near each other in a stroke, to reach a length of 12 inches.
We will now compute all the different combinations for the different orders with and without punchID. When article 1 has a punchID, we will identify this punching-knife with ‘P’, for article 2 we will use ‘Q’ and so on. A combination is indicated as (_ _ R S) for example, meaning that article 3 has a punchID ‘R’ and article 4 a punchID ‘S’, while articles 1 and 2 have no punchID (because they are normal articles).