Background and Setting
In the plastic films industry, “master rolls” of film are slit into smaller length and diameter “finished rolls” on “slitting machines”. The finished rolls are used by customers for packaging applications. e.g. snack foods and cigarettes.

Client Business Objectives

1. Increase production yields
The production scheduling challenge is to assemble customer orders which slit master rolls into finished rolls, so as to maximize master roll material utilization.

2. Honor a variety of operational constraints and objectives such as: The number of slitting knives per machine is limited. Therefore the number of finished rolls which can be produced simultaneousely is restricted. A large order requiring multiple master rolls has to be produced on the same machine consecutavely because no work in process inventory is maintained. Minimizing the changeover times by minimizing the knife changes (number of knives and knife positions) in any given schedule.

3. Improve consistency of quality production schedules
Before the introduction of this system high yield schedules were often generated by postponing the scheduling of difficult sizes (i.e. “cherry picking” the orders). Eventually the difficult sizes had to be produced resulting in much poorer yields. Furthermore, 60% of all schedules were generated on the manufacturing floor completely bypassing the production scheduler because of rush jobs, many of which had been created unnecessarily by cherry picking.

4. Decrease dependence on a single production scheduler
The entire business had grown to depend on one very skilled production scheduler. The new system could easily be used by others to generate good schedules.

5. Free up the schedulers time to interface with customer services,
to negotiate promised delivery times to help improve the efficiency of schedules.

How did UIA Help?

Developed a system to minimize trim losses while honoring all operational constraints
A PC based system utilizing “heuristic” optimization techniques was developed which produced production schedules for the slitting operations.

How the Client Benefited
All objectives were met. After two years of operatin the client reported annual yield savings of $650,000. The customer invested approximately $250,000 for the system realizing a pay back in 4.6 months.