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In November 2013, Swiss group WM Wrapping Machinery completed the testing phase of a full production line for manufacturing two-colour disposable cups in multi-layer polypropylene.
The plant, WM says, is destined to be installed at the site of a major manufacturer (outside of Europe) of disposable items, which is also currently taking delivery of another WM complete in-line system for the production of plates made of co-extruded polystyrene HIPS.
The multi-layer PP line, which is called INTEC FT 900/3, consists of a unit for the automatic dosing and feeding of the raw material in granules, including a system for management and recycling of the ground line waste.
The flat die head of the extrusion feeds a vertical laminating calender with three rolls, creating a sheet with a width of 930 mm and a thickness ranging from 0.2 to 2mm.
The extruded sheet is then sent in-line to the transport system with toothed chains of the model FT 900 thermoforming machine, with a tilting lower platen and a servo-assisted plugging unit. The forming tool can accommodate moulds with a maximum size of 880 x 520mm and has a clamping force of 75,000 DaN. The tilting system of the movable lower platen is based on a double ‘Desmodromic’ system of cams and levers operated by a servomotor.
The mould has 51 cavities for the production of cups with a finished border diameter of 73 mm and a height of 95 mm.
Once thermoformed and cut (an operation that occurs simultaneously in the same mould) the cups are removed from the bottom half-mould which tilts at 75 degrees by a plate with spindles, and are automatically transported to a collection cage, which unloads the various rows of stacked cups on a conveyor belt and continuously feeds a rimming unit with three rotating screws. This turns the upper edge of the cups upwards and then sends the stacks to the counting and packing units.
The waste or the residual perforated polypropylene sheet from which the cups are made is sent in-line to a soundproof grinding mill, which reduces the scrap to flakes and, by means of a blower group, sends it to the dosing/mixing unit located above the extrusion unit. This creates a closed loop from the raw material to the finished product, with the direct in-line recycling of waste materials.
WM says that the INTEC 900/3 system can produce up to 120,000 units of 200 cc cups per hour, minimising energy consumption and significantly increasing automation.