P&G wanted to install a new production line for the production of tissues. Produced tissues can be dry or impregnated with Aloë-Vera lotion. The products always have the same dimensions : 220mm x 110mm x 110mm (WxLxH) and are similar to « facial tissues. The main idea behind the project is to keep the interfolding unit running. To stop the interfolding unit would only lead to an increase of scrap material.
Definition of scrap material:
"Stacks to be scrapped are those with a misaligned bottom sheet or other defects in the stack shape. Scrap level will not exceed 0.4%".
The new installation needed to comply with safety regulations as required by European law. The machines were to be delivered with a CE-conformity and the necessary documentation. Noise level was not to exceed 85 dB at 1m distance.
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Customer Objectives:
- Streamline transfer from interfolding unit to box packer
- Create buffer area to hold 1 minute of production
- Optimise overall quality of stacks
- Avoid cosmetic damage to stacks when packed in cardboard boxes
- Maximize usage of available floorspace
- Reach full production capacity, with minimal scrap in the shortest possible timeframe after installation
- Measure performance of the complete line by means of a "Machine Überwachung System" (system to monitor all up- and down times of the machine, it will also record the reason of a failure)
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Key Customer Selling Points:
- Usage of floor space reduced to a minimum
- Simple solution
- Standard components
- Accessibility of system
- The interfolding unit does not need to be stopped when a problem occurs downstream, but will be slowed down thereby increasing the time available to the operator to solve the outstanding problem
- Stack integrity is kept all the way through from the cutter to the box packer
Shuttleworth Solution:
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The complete production line consists of three units:
- Interfolding unit from Winkler & Dünnebier, with integrated cutter
- Slip-Torque buffer
- Box packer
- The Winkler & Dünnebier works at a nominal output rate of 80 stacks/min. The tissue is unwinded, folded and cut.
- The long folded stack of tissue is cut to length (4 x 220mm) and transported sideways out of the machine. Between each stack, a gap exists of ±30mm, between each "train of 4", a gap exists of ±350mm.
- The trains travel the easy way on a flat belt to the buffer station.
- At the end of the flat belt, a sensor will detect, and count 4 products.
- All 4 products, in the mean time on the infeed bed of the buffer, will be pushed off onto the main buffer table.
- The pusher operates in the following sequence: Push, Lift, Return, Drop, to allow the second batch of 4 products to travel on the infeed section.
- The stacks now travel the hard way on the buffer table until they reach a blade stop.
- A combination of blade stop/overhead mounted brake is used to index single rows into the push-off area.
- An overhead mounted pusher pushes single rows off onto the outfeed bed.
- The stacks are fed into the box packer.
In case of a problem downstream, the Slip-Torque unit will go automatically into buffer mode. The stacks are buffered against the first blade stop. A high level eye is foreseen to indicate that the buffer is full after which the Winkler & Dünnebier will divert the excess products to a scrap outfeed.
Note that the Winkler & Dünnebier will slow down when the buffer unit starts to accumulate, it will not stop. Not stopping the machine reduces the occurance of problems.
How to identify similar opportunities:
Although tissues are not expensive, producing them can be very expensive. Especially when the interfolding unit needs to go through a lot of start/stop cycles. The amount of scrap generated when a problem occurs represents a fair sum.
Look for opportunities where:
- The interfolding unit needs to run continuously (even at a slower rate)
- The cosmetic appearance is important
- Ergonomic issues (accessibility in case of problems/maintenance)
- Efficient use of floorspace