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adjustable crowning polishing roller
PET film & sheet – thickness as low as 100 µm
Brückner Formtec presents a concept for optimizing thin PET film and sheet production – the patented (U.S. Pat. No. 5 484 370) JuBo roll. JuBo stands for Justierbare (=adjustable) Bombage (=crowning) and refers to the first roll in 3 roll stack, the polishing roller.
This patented technology is especially suitable for wide roll stack extrusion lines producing thin film and sheet. It enables premium polished film production in a thickness range between 125 and 1.000 µm. Films down to 100 µm are possible with slightly modified configurations.
Why JuBo?
Thin plastic film manufacturing requires high line pressure for polishing, resulting in roller deflection. Additionally high productivity demands wide film widths, resulting in even higher deflection and thus in an uneven thickness cross profile of the film itself.
To compensate deflection and produce an even thickness profile, convex rolls are commonly used. Such convex rolls with fixed geometry can only cope with one particular setup while highly flexible lines, as those from Brückner Formtec, require adjustable crowning to cover a wide thickness range, various resins and flat die deckling. Therefore, Brückner Formtec has developed the JuBo technology.
What is special about JuBo technology?
JuBo technology does not require complicated, failure prone mechanics. It is based on thermal expansion and incompressibility of oil and thus easily controllable and maintenance-free.
An oil filled cavity is placed underneath the cooling spirals, its shape is calculated by finite element method (FEM). This cavity during operation reaches the temperature level applied to the cooling water of the polishing roller. Depending on the temperature, pressures up to 300 bar can be reached within the oil cavity. This in return creates a very symmetrical deformation of the outer shell of the polishing roller. Result is a crowning up to 100 µm in the centre line of the Jubo roller.
Is it available for any line?
Brückner Formtec JuBo rollers are especially designed for Brückner Formtec equipment. To Brückner Group customers this technology is also available as an upgrade for lines supplied by other machinery manufacturers.
Why produce thin PET roll stock?
Because the industry is demanding thin film and sheet for following applications: |  | General thermoforming
| | | Form-Fill-Seal (FFS)
| | | Credit card overlay film
| | | Graphic arts |
Other issues supporting this industry trend are: | | Downgauging
| | | Peak of petrochemical product prices
| | | Packaging legislation forces producers to use less material |
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Applications
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| | Compensation of roll bending in the rollstack
| | | Uniform polishing and high precision gauge profile at film thickness below 200 µm
| | | Increase of productivity through in-line crowning adjustment during production |
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Function
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| | Special design inflatable oil filled cavity in roller body
| | | Crowning adjustment in-line by thermal expansion i.e. adjusting roller temperature
| | | Crowning shape is optimized for all thicknesses and widths, whereas other systems are designed for one thickness- and width combination only
| | | Maintenance-free |
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Why JuBo?
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| | Thin film requires high line pressure
| | | High line pressure creates high roller deflection
| | | Thickness irregularity is percentual higher in thinner films
| | | Need for compensation of deflection at films below 200 µm – via patented JuBo technology (U.S. Pat. No. 5 484 370 - JuBo roll) |
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