Scheduling of packaging lines in the process industry:An empirical investigation

In the process industry, homogeneous products have to be packed. For an unpacked product (milk, paint), a variety of packaging materials (glass, tin) and packaging sizes (1/2 litre, 1 kilo) are available. Generally, the packaging lines are used for various products (milk, buttermilk) in one type of packaging material (glass) and various packaging sizes (1/2 litre, 1 litre). These possibilities make the scheduling of the packaging lines rather complex.In recent years, under market pressure, the number of products in the process industry has been increased, the order sizes have been reduced, and the delivery times have been shortened. This has caused augmented scheduling tasks and, usually, the scheduling systems supporting these tasks have not followed these changes sufficiently.We have investigated and compared the origins of the increasing complexity of the scheduling problems of several companies in the process industry producing dairy products, pharmaceutical products, tobacco, paint, chocolate products, and foods, and we have analyzed the ways in which these companies deal with this increasing complexity in different situations. Schedulers have to deal with a wide range of information such as due dates, availability of material, sequence-dependent set-up times, and availability of packaging lines and employees. In most cases the scheduling is still done by hand, which is very time-consuming. We show the need for a more adequate support system which will provide necessary information, and speed up the development and evaluation of production schedules. We also discuss future trends with regard to the packaging process, and their likely effect on the scheduling process.