Lines for polished / thermoforming sheets: Modules
- Schematic representation of a 3-layer polished sheet / thermoforming sheet extrusion line
In addition to the extrusion section, the coextrusion unit and the sheet die-head, the polishing stacks on which the melt is formed and cooled are especially important for manufacturing high-quality polished sheets. With the MIREX-S, MIREX-W and MIREX-TS series, the Reifenhäuser program includes polishing stacks for all possible applications.
1 Plasticising unit
In the production of polished sheets Reifenhäuser uses its proven single- and twin-screw extruders to achieve optimal plasticizing and blending effects. The following options are available depending on the required product:
- Highly efficient feed systems with grooves enabling high output rates in processing all raw materials
- High-efficient vacuum venting by special venting screws for hygroscopic polymers
- High-performance barrier screws
- Combination screws capable of processing various polymers without the necessity of a screw change
- Barrels and screws with extremely hard-wearing, armoured surfaces
- Space-saving Reitorque coextruders for multi-layer lines
2 Forming section
The coextrusion process has gained increasing importance for the development of sheets that are capable of being polished. In earlier years, only typical 2-layer composites such as PS/SB were manufactured. Today composites with up to 9 layers dominate. With the proven and patented coextrusion slider-adapter process, Reifenhäuser is able to optimally manufacture these film composites.
The polished sheet die-heads are available in the customary nominal widths between 850 and 2,200 mm with throughputs of 200 to 2,000 kg/h. Continuous development of the distributor geometries guarantees optimal tolerances, a broad operation spectrum and low pressure use. Additional characteristics are:
- Inlet and distributor system designed for mono- and adapter coextrusion
- Flow channel with optimised flow properties, suitable for all polymers.
- Inline Slot Regulation (ISR II system ) for changing the lip gap during production.
3 Polishing stack
In the polishing stack, the melt is formed into a thermoforming sheet and cooled down. Exact temperature control and uniform running of the polishing rolls are the prerequisites for production of high-quality sheets with perfect surfaces.
MIREX-S polishing stacks for vertical extrusion offer the following advantages:
- controlled melt flow into the polishing nip, also for thin sheet with low melt stability
- perfect handling allowing good view into the polishing nip
- feed and web position easily adjustable
- no condensation on the sheet
- optimum chill roll operation for thin sheet production
However, Reifenhäuser also caters for the possibility of horizontal extrusion which involves the use of the "MIREX-W" polishing stacks.
Advantages of horizontal extrusion:
- particularly suitable for sheet of high melt stability
- simple line assembly
- easy access
- also suitable for combining thermoforming sheet/standard sheet lines
MIREX-S polishing stack
- vertical extrusion
- compact design
- preferred basic model for in-line extrusion in conjunction with automatic vacuum forming machines
- 900 - 1600 mm roll width, other widths upon request
MIREX-W polishing stack
- horizontal extrusion
- also available in large widths
- also suitable for in-line extrusion
- also suitable for combination lines for the production of thermoforming and standard sheets
- 900 - 2300 mm roll width, other widths upon request
- operation from top or bottom
MIREX-TS polishing stack
- vertical extrusion
- compact design
- high-performance polishing of optically exacting sheet products, e.g. from PP or PET
- particularly suitable for thin sheets down to 0.15 mm, double-polished
- 900 - 2200 mm roll width, other widths upon request
- optional available width swivable 3rd roll
Air Knives
Air knives are additionally used for the manufacture of thin sheets that cannot be polished by the nip.
These enable thin sheets to be manufactured using the chill roll process.
4 Sheet post-treatment section
For sheet treatment after polishing additional line modules, e.g. thickness gauge and pre-treating station can be used:
Depending on the product and production capacity, additional cooling rolls can be placed downstream from the polishing stack. These rolls can be integrated into the cooling circuit. The sheet thickness can be measured by magnetic induction systems or isotope measuring units. Other systems can be integrated on demand.
Longitudinal cutting units:
- blade cutter unit or
- rotating cutter unit
5 Winder
Reifenhäuser's extensive product program for thermoforming sheet lines include winders that meet a wide range of customer-specific requirements. They are electrically driven and permit reel diameters of up to 2,000 mm.
Product type, sheet rigidity and thickness as well as production speed are decisive factors in selecting the right winder.
Junbo reel winder
- with and without accumulator
- with and without auxiliary haul-off unit
- with and without pneumatic crosscutter
- max. reel diameter 1600 mm or 2000 mm
Automatic winder
- with auxiliary haul-off unit
- with accumulator
- with automatic web lay-on
- with pneumatic crosscutter
- max. reel diameter 1600 mm or 2000 mm
5 Automation
REIcontrol - the automation system
REIcontrol is an automation system that meets the constantly growing demands placed on quality improvement and rationalisation. This system, developed by Reifenhäuser, monitors, controls and regulates extrusion line and process parameters.
Extruder and die temperatures
- melt pressures
- line and haul-off speed
- start-up and shut-down parameters
- fault messages
- throughput control (optional)
- multi-component dosing (gravimetric/volumetric) (optional)
- recording of trend data
- printing of trend data
- alarm logging
REIcontrol Plus - the logging system
REIcontrol Plus is a logging system that satisfies the steadily increasing demands for process logging which is of great importance for quality management.
This system has been developed by Reifenhäuser to include functions for logging and memorizing of line and process parameters.
- recording of trend data
- printing of process data in tabular form
- printing of trend data
- formulation management
- daily logging of inputs and alarms
