Afstudeerscriptie P.J. van Dijk
---
Vertrouwelijk Pagina 7 1-9-2008
Summary
Coca-Cola Enterprises (CCE) is one of the biggest producers of non-alcoholic beverages in the world. The production for the Dutch market takes place in Dongen. Three years ago CCE Dongen switched over from the return PET-bottle to the one-off PET-bottle. Due to this changing three new production lines (At CCE Dongen they called them line 4, 5 & 6) were placed, which are mainly the same. Each line has a capacity of 30.000 bottles per hour and is suitable for big batches. Last years the batches became smaller, because the market wished more and more product diversity. Consequence was that the number of changeovers increased and that the changeover time more and more influences the efficiency of the lines. That is the reason why CCE Dongen started this year the so-called SMED-project, with the aim to reduce the changeover time. The theory of SMED was developed by the Japanese Shigeo Shingo and applied for the first time at Toyota. This car producer was able to reduce the changeover time of a stamping press from 4 hour to 3 minutes. CCE Dongen wants to reach the following with the SMED-project: 1-2% more efficiency at line 4, 2-3 more efficiency at line 5 and 6% more efficiency at line 6. The reason why the aim differs for each line has to do with the average size of the batches and the number of changeovers per production line.
As said earlier the three production lines are mainly identical. Every line starts with a blower, where the bottles are produced. From the blower the bottles are transported by an air conveyor to a labelling machine. After that the bottles are filled and conveyed to a so called variopack. This machine packs the bottles per 4,6, 12 or 24. Hereafter the packs go the palletiser, where they are piled up.
During a changeover not always every machine has to be changed. Globally the changeovers could be divided in three categories on the base of time. Category 1 are changeovers with a switch to another bottle. The changeover time depends on the bottle blower. Category 2 are changeovers where there is switched to another kind of beverage. The changeover time depends on the rinse process of the filler. Finally category 3; here takes place a switch to another pack. In this case only the variopack and the palletiser have to be changed. To get knowledge of the changeover process from each machine the changeover tasks are analysed and visualised in a flowchart. Further was every changeover registered during a period of 10 weeks with the help of Line View, a program which is used by CCE to monitor the production lines. The average changeover time of category 1 was 150 minutes. Changeovers of category 2 and 3 take on average 90, respectively 80 minutes.
The variance of the changeover time was enormous. Two changeovers from the same category, which differ a factor two in time where no exception.
To reduce the changeover time first is looked how things are organised. There is observed that each team has his own structure in doing the changeover. Next thing is man occupancy: approximately 33% of the changeovers are carried out with not all the fixed staff available at the lines. These two factors mainly explain why the variance in changeover time is so huge. To get rid of this variance every team must have the same changeover structure. Leadership and preparation are hereby important terms. Before a changeover takes place could be inventoried how many people are available. If necessary, people could be borrowed temporarily from other departments to help with the changeover. When things are well managed it must be possible to do 90% of the changeovers with plenary staff.
Further is the changeover time much influenced by the order of products. The best order of products for the production department is simply to determine, but externally influences stipulate that the optimum product order could rarely be used.
Finally the sizes of the batches: sometimes batches are produced where less than 50% output could be gained. It is advised to look if there is still money in it.
Afstudeerscriptie P.J. van Dijk
---
Vertrouwelijk Pagina 8 1-9-2008
In the past there was a rinse with water at every change of beverage. Under certain conditions there had to take place a CIP of at least 2 hours with hydroxide. At the base of measurements and intuition was found that at certain changeovers (By example from Coca-Cola Light to Coca-Cola) a rinse with water is not necessary. In this case blowing the system clean and dry with CO2 is just enough; this principle is
called blow and go and is twice as short as a rinse with water. Also is argued to change the conditions for a CIP in such way that a cleaning with hydroxide is only necessary in the weekend.
Further the BRIX was measured by hand in the past, whereas advanced measuring systems registered the BRIX continually. Deleting this measurement by hand and using the advanced measuring systems saves 20 minutes changeover time.
In the case of the blower could the changeover time 40 minutes reduced, when the inside moulds are placed externally in the outside moulds. Further could be saved 30 minutes by using one stretching rod. According to the theory it should be possible to blow all the bottle types with the same stretching rod. During a changeover it is important that tasks take place parallel as much as possible. In the past it was not possible to adjust the labeller, variopack and palletiser precise before bottles were sent by the blower. By using dummy bottles fine tuning is possible at the labeller, without bottles from the blower. In case of the variopack and the palletiser plastic moulds, which have the size of the packs are the solution.
Mechanical changes are especially important for the blowers and the conveyor conductance between the variopack and the palletiser. Changing the moulds of the blower takes a lot of time and many times the same tasks have to be done (Sometimes more than 300 bolts have to be unscrewed and screwed). Using click systems should save much time and work. The producer of the blower has already developed a quick changeover mechanism for the bottom moulds. When this mechanism is applied at line 6, the pay-back time is less than a year.
To adjust the conveyor conductance between the variopack and the palletiser dozens of buds have to be unfixed and fixed. Using rapid clutches could save here a lot of time and energy.
When all the above mentioned issues are applied the following average changeover times may be expected: category 1 is 40 minutes, category 2 is 35 minutes and category 3 is 25 minutes. When a changeover is managed well these times are already realised.
In case these times become standard the output of line 4 increases with 5%, line 5 increases 12% and line 6 increases 13% at the current batch size. In money it means a saving of costs, which is equal to 7,2 million euro per year.
Conclusion is that the aims of CCE with the SMED-project are reached by far. Briefly a good organisation, process changes, parallelising and mechanical changes make a reduction of the changeover time possible. Although the batch size is decreased, there is still a lot of potential in these mass production lines. But advised is to discover at which batch size the financial break-even point lies.
