Uteco sleeve trolley at drupa
There is a wide range of ancillary equipment available to flexo printers that can be used to support the operation of a press, a sleeve or plate systems or the pressroom itself. David Atkinson looks at this important sector.
Press cleaning
With machine time on wide web presses being at such a premium, printers with these machines need to keep downtime to a minimum. As washing down the press tends to be the most time-consuming operation during job changeover, this is an aspect that needs close attention. Most wide web CI press manufacturers, such as flexotecnica with its ‘Speedy Clean’ fully automatic wash-up system, offer the option of auto wash systems on new equipment. With fully automated systems, the complete wash cycle can be pre-programmed and a complete wash down of all print units can be accomplished in a matter of minutes, as all units can be washed simultaneously. This represents a significant time saving during job changeover and becomes increasingly important as the average number of job changes per shift increases.
Any printer with a wide web press that is not fitted with an auto wash system can relatively easily retrofit one as they are offered by a number of suppliers. Ofem Converting offers a fully automatic wash-up system (IPW) and a semi-automatic wash-up system (S-IPW). On the fully automatic system a preset programme controls the complete wash-up cycle but there is still the means to re-programme and customise various parameters. With the semi-automatic system every operation is manually activated on each individual station.
New Celio Engineering has developed an auto wash system that has a control unit and piping system that enables viscosity control and wash-up to be combined. The washing process is fully automatic and it is possible to choose different levels of wash intensity. Print units can be washed independently or simultaneously.
Ross Howie Graphic Equipment’s Expert RC System is a completely automatic wash up system that can also accept viscosity control. The system includes two pneumatic membrane pumps and a rotator valve (patent pending), which is controlled by a single electro valve and enables the distribution of fluids during the different washing cycles. Each system is an independent unit that can be moved from one colour station to another or from one press to another.
Because of its large surface area the central drum is a difficult and time consuming aspect of cleaning on wide web CI presses. Dirt can build up on the drum as a result of transfer from the web due to materials such as slip additives, dust and debris as well as ink transfer to the drum after a web break, ink leakage or due to printing over the edge of the web. The cleanup operation typically involves a couple of printers, one on either side of the drum, who manually clean the drum as the press is inched.
Rossini has developed Evolution, an automatic CI drum cleaning system that minimises the time it takes for drum cleaning and also improves press safety. The system consists of a cloth loaded cassette that can be supplied with the appropriate cleaning agent according to the ink system. When the drum requires cleaning, the cassette is brought into contact with the drum where it oscillates across the full drum width thus enabling the cloth, which is primed with cleaning solution to rapidly clean the entire drum. The system has a touch screen control from which the cleaning program can be customised. With such a system, it is possible to clean the drum on a regular basis during job change over thus maximising press up time and improving overall print quality and job consistency.
Corona treatment
Filmic substrates require treatment before printing so as to increase their surface energy and promote adhesion of the ink. This is normally done at the manufacturing stage but as treatment decays over time due to migration of additives, and some ink systems such as water based require higher levels of treatment it is, under some circumstances, useful to fit a corona discharge treater to the press. Corona discharge treaters consist of a power supply unit and a treater box that is fitted to the press in line with the web. The treatment level that can be achieved is dependent on the press width, press speed and the output of the power supply unit so it is important that the unit is correctly sized.
Vetaphone’s open design corona stations have been developed to suit all converting processes. Automatic power disconnection and reconnection is incorporated in the design, as is electrode realignment and air gap-settings. They can be fitted with the Quick Change Cartridge system which minimises downtime and is aimed at web widths from 100 mm to up to 2500 mm.
Corona Supplies Limited offers advice and a range of treaters for flexo presses for conductive and non conductive substrates. These units, which have easy to maintain electrodes and low inertia base rollers, are compact, of open style construction with ozone extraction at source and suitable for press speeds of up to 1500 m/min.
Since 2005, Active Surface Technology has supported and supplied Ahlbrandt corona treatment systems for the UK manufacturing industry and is able to offer the full range of Ahlbrandt treater systems for on press treatment of films.
As well as a range of corona treaters, the company also offers two sided web cleaning by means of corona discharge. During printing, loose particles can be attracted onto the surface of electrostatically charged webs where they adhere until there is a conductive discharge. The company explains that where non conductive materials, such as paper or plastic, are concerned the surface charge cannot be removed until the air itself is made conductive. This is achieved by ionising the air using very high voltage to eliminate the electrostatic charge on the surface of the web. As the system is contactless in operation the surface of the material is not impaired.
Other cleaning methods
Non-contact web cleaning can also be achieved by means of systems based on special high suction vacuums. Static eliminator bars are normally incorporated into this form of non contact web cleaner as any charge on the web makes it harder to remove dust. Contact web cleaners have sticky rollers that run in contact with the web and are generally used on narrow web presses.
For the wide web market, Meech offer the ShearClean non-contact web cleaner that can be used to clean both sides of the web. The cleaning head incorporates proprietary ‘non-contact’ cotton covered cleaning rollers and ionising bars for control of static charges. The system is suitable for press speeds up to 600 m/min and web widths up to 1.8 metres.
Hildebrand Technology offers a range of web cleaners, with the Xstream being best suited to films and foils where it is necessary to remove small particles. This is a non-contact system that incorporates a special aerodynamic nozzle that is placed close to the web and which, in combination with the vacuum and web speed, generates a high velocity air flow. This high velocity air breaks the boundary layer on the web and forces dust and other particles into the cleaning module. A static neutralising system is placed before the cleaning head to produce a neutral surface that facilitates easier removal of dust and debris.
The Kelva web cleaning system consists of a non-contact web cleaner head with passive or active antistatic equipment, a filter/fan unit, dust collection and control unit. A non-contact static discharger located before the web cleaner is used to deionise the surface of the web. Pressurised warm air is blown through a slot in the cleaning head to loosen the dust and facilitate its removal by the vacuum.
Adaptor sleeves
With an increasing number of wide web printers working with sleeve systems, the use of adaptor, or bridging sleeves as they are sometimes known, is growing. Adaptor sleeves allow printers to work with thinner walled, lighter and more cost effective plate sleeves by bridging the gap between the mandrel and the plate sleeve. Because each adaptor size is used with a range of plate sleeves and they have to meet high demands on the press, their accuracy and stability is of critical importance. Carbon fibre offers a number of favourable properties, such as high strength and stiffness, and it is for this reason that adaptor sleeves for the most demanding applications tend to be made from this material.
Rossini is the only sleeve supplier with its own carbon fibre department and this enables it to carry out its own research. It offers two carbon fibre adaptor sleeves, the Carrier sleeve and the Carbobridge sleeve. The Carbobridge sleeve is a more expensive high modulus carbon fibre adapter sleeve, without a compressible layer, that provides the ability to print at 700 m/min. It is available in three versions: the Flow-Thru, which uses a single mandrel air source for both adapter and plate sleeve, the Standard, which uses a secondary air source, and the Custom, which can be produced to the specifications of any OEM press manufacturer. The Carrier sleeve is available in these versions plus an additional high modulus version that is designed to reduce vibration on high speed wide web presses.
The Flint Group rotec Atlas Adaptor also has a carbon fibre structure for maximum printing performance and low vibration. It is available as the rotec Atlas Altro Adaptor with wall thickness from 24 to 100 mm and the rotec Atlas Unifit Adaptor with wall thickness from 21 to 100 mm. Both are equipped with a customised air conduction system and can be combined with various types of sleeves. Aluminium blanks with a reinforced location notch are used at both ends to prevent damage to the fibre glass base. A polyurethane coating improves scratch and solvent resistance and makes it possible to grind out minor surface damage.
The Polywest Hybrid Sleeve Adaptor (HSA) has an innovative structure in that it is built as an inner and outer sleeve connected with each other by radial supports. A combination of carbon fibre and other materials is used to optimise cost efficiency and weight and wall thicknesses from 17 to 150 mm can be achieved. The exterior sleeve consists of glass or carbon fibre and can have a hard or soft surface depending on print preference.
Trelleborg is a major producer of sleeves, which are sold under the Axcyl brand and includes bridge and repeat build-up sleeves plus thin sleeves for plate mounting. The extremely stable and lightweight structure of the sleeves ensures vibration filtration and smooth mounting.
Sleeve storage systems
With increased use of sleeves comes the need to store them and an increasing number of companies including Rossini, Sandon Global Engraving, ST Converting, Simec, Anderson & Vreeland and Polywest now offer sleeve storage solutions. Some of these storage solutions have been designed with plate sleeves and adaptor sleeves in mind and others specifically for anilox sleeves.
Rossini offers adjustable racks made from steel that will accept varying length sleeves. The height of the racks can be easily adjusted and, depending on the length and diameter of the sleeves, can accept up to two sleeve levels per rack and up to three rows per level. The racks sit within a main framework, with two being fixed in the framework and three being mobile and easy to move from either end. A modular design allows easy expansion. This enables a basic system consisting of frame and five racks to accommodate up to 390 sleeves with a diameter of 150 mm or less and length 1340 mm or less.
Flex Essentials Inc has developed the FlexStor sleeve storage system for storing sleeves vertically inside sturdy racks. The sleeves rest on rubber pads and centre distances between sleeves are infinitely adjustable so as to allow storage of printing sleeves of any inside or outside diameter and to maximise storage capacity. Frictionless rollers and guides enable easy carriage movement when accessing sleeves. The system is modular and can be custom designed. The company also offers a manual sleeve storage system that it says is a cost effective method of storing sleeves in an organised fashion and that requires a minimum of floor space.
Anderson & Vreeland offers a number of sleeve storage solutions. The Beartech 2000 flexo sleeve storage solution is a fully automated carousel that consists of 29 carriers, each of which is able to accommodate approximately 20 sleeves. The system features a computerised control panel providing inventory management for up to 580 flexo sleeves. Sleeves with diameters from 100 to 250 mm and up to 1680 mm in length can be stored. And when a sleeve is selected, it is automatically positioned in front of the loading/unloading platform. The Self Standing sleeve storage system is a modular vertical sleeve storage system that can be expanded vertically or horizontally. One standard module can store between 196 and 336 sleeves. For printers with a small sleeve inventory, the company offers Beartech’s Self-Standing racks that have four caster wheels for easy mobility and that can accommodate sleeves up to 2130 mm in length.
For printing sleeves or cylinders, Sys Tec Converting offers a carousel system with a capacity from 192 sleeves or from 60 plate cylinders. This will accept sleeves and cylinders of all dimensions. For maximum flexibility and adaptation, the system is a modular concept based on a steel frame that permits future extension in elevation as well as plan. The frame itself accommodates four suspended sleeve racks made from extruded aluminium. Options include remote control and barcode management for rapid identification and location of sleeves.
Recyl has produced the STC trolley for the transport and storage of anilox and plate sleeves. The trolleys are available for large or small width sleeves and are designed to accommodate 6, 8 or 10 sleeves.
Last year Sandon Global Engraving Ltd announced a vertical storage carousel to meet the needs of its sleeved anilox customers. This is a vertical system designed to be functional, space saving, mobile and easy to use while at the same time being able to accommodate sleeve covers for maximum protection.
Also for anilox sleeves, the Simec Group has developed the Revolver storage solution. This is also a vertical storage system that is easy to move and will accommodate up to 10 sleeves with a maximum length of 1350 mm and maximum diameter of 200 mm. Other versions include the Revolver Self and the Revolver SelfClose.
