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Heuristic Method for Minimizing Trim Loss in the Paper Industry

IP.com Disclosure Number: IPCOM000074903D
Original Publication Date: 1971-Jun-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 3 page(s) / 55K

Publishing Venue

IBM

Related People

Marconi, R: AUTHOR

Abstract

This is a method for scheduling the work of a paper machine with an on-line Duplex cutter for sheet paper making. The cutting plans are determined in order to have the lowest possible total cutting cost, considering the cost of the raw material and the number of blade changes.

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Heuristic Method for Minimizing Trim Loss in the Paper Industry

This is a method for scheduling the work of a paper machine with an on-line Duplex cutter for sheet paper making. The cutting plans are determined in order to have the lowest possible total cutting cost, considering the cost of the raw material and the number of blade changes.

From all orders, we choose those which must enter into production. They are divided into groups, homogeneous in paper quality and substance. In each group we have to find the most suitable combinations in order to minimize the trim loss.

The basic procedure is as follows:
1) All possible combinations are made by grouping together,

with respect to the width of the paper machine, the widths

of the orders (of the group in question). Only combinations

with two different types of orders are considered in order

to satisfy the constraints of the Duplex cutter
2) The combination with the lowest trim loss is chosen and the

weight to be cut, according to that combination, is calculated

so that at least one of the orders of the combination will be

filled
3) The quantities of orders to be scheduled are updated,

subtracting the quantities schedule in point 2)
4) A check is made to see whether all the orders have been

scheduled: if not, go back to point 1) repeating the procedure

with the remaining orders; if so, the procedure is over.

This procedure, is simple and very fast and, therefore, economic from the point of view of computer time; however, problems could arise in the following situations:
a) if combinations are chosen at random which increase trim loss;
b) if the scheduled combinations are of such a small weight that

they are uneconomical; and
c) if there are too many combinations with consequent excessive

splitting of orders.

To avoid the above inconveniences as much as possible, we make use of special penalties and gains introduced in the combination evaluation phase, so that the choice is not guided only by trim loss minimization.

Thus is introduced:
a)...