Dyeing Route Economics: Which Machine for This Lot

How to read this sheet

Each route is a fixed cost to start plus a running cost per kilogram, so each is the cheapest over one band of lot sizes or over none, and the sheet reports the band rather than a single verdict - the answer to "which machine" is a routing rule and not a preference. A route reported as cheapest up to zero kilograms has no upper limit; one flagged as never cheapest is dominated at every lot size, which is worth knowing before it is scheduled again. The start-up loss is what makes this worth computing. It is cloth rather than money - threaded through, run as leader, sacrificed to stabilise the shade, cut off as tail - so its cost follows the value of the goods and not the cost of the machine. Two dyehouses with identical equipment therefore have different crossovers, and a house that moves from commodity greige to a finer cloth should expect its routing rules to change without having bought anything. Charge it honestly: the loss on a first run of an unfamiliar shade is not the loss on a repeat. What is not here matters. Quality differs by route and is not costed - a pad-batch shade is not an exhaust shade, and right-first-time rates differ enough to reverse a marginal comparison on their own. Capacity is ignored, so a route that is cheapest and fully booked is not available; that is a scheduling question and this sheet does not know the schedule. Minimum lot sizes, fastness requirements that rule out a route entirely, and the effluent load differing in kind rather than only in volume are all outside it. And the machine cost per hour should be an incremental figure while the house has spare capacity, and the contribution the hour would otherwise earn once it does not.