PEME was tasked with investigating a reoccurring reliability problem with the feed of filled boxes (outers) into a box closer. The issue was causing a loss of production due to frequent stoppages as a result of blockages caused by boxes not being correctly configured for entry to the box closer. Operator intervention was then required to clear the blockage. Significant maintenance effort was also being expended in trying to adjust the box closer mechanism to rectify the problem.
The filled boxes are fed along conveyors and once they have gone through the first gluing section of the box closer they are turned through ninety degrees by the box closer mechanism before entering the second section where the lid is folded over and sealed. This was designed to be achieved through the box hitting an end-stop on its corner and then a complex arrangement of 3 separate belts driven by their own drive at different speeds, pulling the box through ninety degrees and feeding into the second stage of the box closer.
We conducted a Reliability Improvement investigation using the PEME Fast-track Root Cause Analysis (RCA) approach and identified that the issue was influenced by boxes containing different recipes / weights and that the bottom of the boxes were not always flat. Simply adjusting the mechanism was not addressing these variables.
PEME identified that the addition of a guide rail would control and correct the box angle going into the second gluing section and designed, manufactured and installed a guide rail. Originally the boxes were either under or over turning, which was resolved by introduction of the guide rail. This modification also simplified the functionality required of the box closer mechanism, as this was now not being used to turn the box, letting the 3 belts to be driven at the same speed by a single drive and therefore, allowing the removal of 2 drives.
Since the implementation of the changes there have been no occurrences of the same issue which has led to a Productivity Improvement of up to ten hours a week.