Static elimination
Many factors contribute to creation of static electricity:
a) Contact and separation (friction)
Whenever two dissimilar materials come in contact with each other and separate, one of the materials loses electrons and the other gains electrons. This phenomenon is called “triboelectric effect”. Static charges are developed on the surface of one of the materials depending on its relative position in triboelectric series.
b) Changes in temperature
Changes in temperature cause separation of charge in the atoms or molecules of certain materials. This is called “pyroelectric effect”.
c) Changes in pressure
Applied mechanical stress generates a separation of charge in certain types of crystals and ceramic molecules. This is called “Piezoelectric effect”.
d) Induction
A charged object brought close to an electrically neutral object causes a separation of charge within the neutral object. This results in static charges.
It is difficult to measure static charges in Coulomb – the SI unit of electric charge (equal to the quantity of electricity conveyed in one second by a current of one ampere). An easier method is to measure static charges in terms of surface voltage in kilo volts (kV) using a static charge meter.
Valstat static charge meters measure ±20 kV at 25 mm distance from the surface of substrates and higher voltages at proportionally higher gaps.
Static charges are less in humid conditions and more in dry atmosphere.
Active static eliminators are the ones which rely on AC or DC power supply which generate high voltages. This high voltage in turn helps in generating ions of positive and negative polarities which will help to neutralise excess charges present on the surface of the target substrate. They are best suited to eliminate static charges from fast moving webs, sheets, films and such.
A passive static eliminator is one which does not depend on an electric power supply to function. These are generally in the form of a brush or pad connected to ground. They help to drain excess charges from the substrate to the ground. These are best suited to considerably reduce the high static charge levels from substrates such as moving sheets, films, as they do not completely eliminate static charges.
AC static eliminating systems work on AC power supply. They contain a set of electrodes generating positive and negative ions during respective cycles of AC supply.
DC static eliminating systems work on DC power supply. They contain two separate sets of electrodes. The electrodes connected to positive DC supply generate positive ions and the electrodes connected to negative DC supply generate negative ions.
All the static eliminating systems do the same job of generating ions. It is the application which decides the appropriate system to use.
Valstat static eliminators are shock-less and spark-free. Though the operating voltage is in the order of kilo volts, the current is limited to a few milli amperes and hence it will not yield any shock upon touching the electrode.
No. The Valstat bars are not recommended to be installed against metal rollers as the ions generated by the static bars tend to get earthed through the metal rollers which are attached to the machine frame, rendering them ineffective.
Regular static eliminating bars cannot be used in explosion prone areas like print stations of a printing machine. Separate ATEX certified explosion proof Valstat static eliminating systems are available for such applications. Please consult our product office to know more.
Only some specialised applications involve handling metallised inks/films. It is not recommended to use active bars in such applications. We suggest using passive discharging systems in such cases.
Valstat static eliminators are easy to operate and require very less maintenance. The electrode tips must be cleaned regularly using a nylon brush. The bars must be cleaned to remove dust, dirt and scales regularly. Details have been covered in our instructions manual regarding the same.
The passive brushes are made up of 35 micron-controlled resistivity fibres. The fibres are extremely soft and durable and are housed in a powder coated aluminium section. When positioned very close or just about touching a charged web, Valstat passive brushes will minimise the static charges and send it to ground. Hence, they are ideally suited for applications in hazardous areas.
Antistatic touch pads help to drain off the static charges present on human body. Valstat antistatic touch pads contain a static dissipative layer which will conduct the static charges safely to ground and keep the humans safe of unwanted static charge build up.
Static charging
Just opposite to static elimination, here, a controlled level of static charges is transmitted on non-conductive surface that provides temporary bonding between the materials. The static charging is useful in applications such as stacking, printing, edge pinning, in-mould labelling.
Valstat electrostatic charging electrodes generate a controlled static charge that create a temporary adhesion between surfaces.
Valstat VC series static charging electrodes are available in two variants; point static chargers and linear static charging bars. Both are supplied with high voltage cable enclosed in a flexible conduit.
Point static chargers are suitable for applications that require localised charging, like edge pinning, in-mould labelling etc. Linear charging bars are used to generate electrostatic charges in linear applications like sheet stacking, pinning tracking etc.
Valstat static charging bars are easy to operate and require very less maintenance. The electrode tips must be cleaned regularly using a nylon brush. The bars must be cleaned to remove dust, dirt and scales regularly. Details have been covered in our instructions manual regarding the same.
Static monitoring
Static monitoring system is measuring and monitoring equipment to identify the location of static charges and its magnitude and polarity.
The Valstat V205 static charge meter is an offline, compact, digital, non-contact, electrostatic surface voltmeter, designed to locate and measure surface voltage on stationary and moving objects.
AxisValence also offers cloud based and real-time static charge monitoring system Valstat SM20 for accurate and continuous monitoring. In this system, electrostatic sensor is fixed at the location where the charge level on a moving target is to be monitored. Each sensor is connected to the respective Valstat field station controller, which in turn are connected to a common touch panel. Depending on needed sensing points, the application and requirements of the user, the common touch panel is suitably located for monitoring and control purpose.
The distance range of Valstat V205 hand-held static meter is 50 mm from the object.
The distance range of Valstat SM20 is 25 to 75 mm from the object.
Camera-based web videos for print viewing
The viewing area of ViewAXIS Mega is 128 mm (w) × 80 mm (h).
The viewing area of our advanced web viewing system ViewAXIS Giga is 185 mm (w) x 140 mm (h) @ 1 x optical zoom at 266 DPI resolution and 13 mm x 10 mm @14 x optical zoom at 3783 DPI resolution.
The resolution of ViewAXIS Mega is 1900 x 1200 pixels and the zooming capacity is 4x;
In case of ViewAXIS Giga is 1936 x 1464 pixels and the zooming capacity is 16x.
The ViewAXIS Mega comes with 22″ full HD, LED backlit, touch screen, while the ViewAXIS Giga system comes with 32” full HD, full HD, LED backlit, touch screen. The optional dual monitor is also available.
Our system gives steady image at low speed 20 mpm to 350 mpm. For some applications, it can be used up to 1000 mpm.
Yes, both ViewAXIS Mega and ViewAXIS Giga can provide steady image for reflective films.
We can recall 4 memory positions for easy and quick access in manual mode but not in auto scan mode.
ViewAXIS Giga display allow to show the full repeat image, however, ViewAXIS Mega doesn’t have such capability.
X-ray vision is a method by way of which a viewer can see underneath the colours visible on the surface to the naked eye.
Optical zoom brings objects closer during capture, maintaining image quality by physically adjusting the lens. In contrast, digital zoom enlarges a portion of the image after capture, leading to a higher risk of quality loss, akin to pixelation when magnifying a small image.
100% print defect detection system
A line scan camera-based 100% print defect detection system is used during the printing process to continuously inspect the print for any deviations when compared with print artwork. It utilises high-resolution line scan cameras to capture images, and image processing software to analyse the entire print repeat, ensuring 100% inspection of the production run.
The line scan camera has pixels arranged as a single row. This captures the image line by line as the substrate moves towards the rewinder. The image processing software recreates the print in real-time and analyses defects. Print defects like misprints, misregisters, color variations, streaks, hazing, and any other print related anomalies are detected. The system triggers an audio, visual alert for immediate corrective action as well as registers the defects as an electronic stamp. A roll-map is saved which has the x and y coordinates of each defect.
Common defects that this system can detect include misprints, color variations, streaks, bleeding, missing or extra prints, ink splatters, registration errors, drags, holes and other imperfections that affect print quality.
Yes, the defect detection systems can be seamlessly integrated into any web based printing machine.
Yes, these systems are typically customisable and adaptable for different printing applications, substrates, and printing processes. They can be configured to suit specific requirements and adjusted for defect sizes, different materials, printing speeds, and defect identification parameters.
Yes, the system can be configured to distinguish between critical defects that impact the product’s quality and minor imperfections that might not affect the overall usability. This customisation helps in setting different thresholds for defect identification.
The system gives a comparative Delta E value to evaluate colour variation. This value assists in examining the perceived difference between colours.
A roll-map is prepared for each printed roll. The roll-map captures information about a production run, such as roll length, location, and type of defects for quality control purposes. This roll-map can be loaded on an inspection rewinder machine. The QC checker can delete non-critical defects from the roll-map, retaining the critical ones. The final roll-map with critical defects is integrated with the inspection rewinder, stopping the machine at each defect. The operator can cut the defect portion from the roll, thereby, ensuring a defect free final product.
100% surface inspection system
A line scan camera-based 100% surface defect detection system is used during the process to continuously inspect the substrate for any deviations. It utilises high-resolution line scan cameras to capture data, and processing software to analyse the surface for defects.
Line scan camera systems capture images line by line, providing high-resolution scans of an entire surface, making them ideal for continuous and comprehensive inspection.
The system can detect a wide range of defects, including holes, dents, dark spots, stains, gels, creases, fisheyes, wrinkles, splices, scratches, coating voids, insects, patches, and shade variations, besides others.
Yes, this system is designed for integration with existing production lines, allowing seamless inclusion in various industries.
Yes, these systems are versatile and can be configured to inspect various surfaces and materials commonly used across different industries.
The systems use dark-field, bright-field and angular lighting besides incorporating adaptive features to handle varying ambient conditions.
Yes, the system’s stored data can be used to analyse historical defect patterns, identifying trends for continuous process improvement and maintenance.
A.T.E. Service team provides technical assistance, software updates, calibration services, besides troubleshooting.
Yes, A.T.E. Service team provides remote troubleshooting, allowing technicians to diagnose issues and provide guidance or support without being physically present on-site.
Ink handling
Ink agitation refers to the process of stirring or mixing ink to ensure a uniform consistency and prevent settling or separation of its components.
Inks used in rotogravure and flexographic printing are “thixotropic” in nature. When kept in a stationary condition, the inks tend to thicken as against when agitated and circulated where they tend to thin out. It is just like a ketchup bottle – when the bottle is shaken, the ketchup tends to come out quickly as against trying to pour the ketch up from a bottle which was at rest for quite some time. Hence there is a continuous need to circulate ink between the print deck and the ink tank.
Valflow centrifugal pumps are best suited for ink circulating application as they help mixing and agitation of the ink and give an impeccable flow.
Valflow ink pumps require very low maintenance like cleaning the impeller once in a while. Standard operating and maintenance procedures are shared in our instructions manual.
Yes, you can order spares, accessories, and consumables separately.
Ink filter
Contaminants in the ink could be either metallic or non-metallic. Metallic contaminants are majorly the doctor blade worn outs which get into the ink through continuous circulation of ink between the tank and the tray. Non-metallic contaminants are generally in the form of undiluted pigments and dust in the air.
Valflow ink filters are very easy to maintain. The filter cartridge must be cleaned periodically depending on contaminants accumulated therein. However, a spare cartridge can be kept to quickly replace the dirty cartridge to ensure hassle free operation. Detailed operating and maintenance procedures are shared in our instructions manual.
The Valflow FC30 filter cartridge is non-disposable as it is made of SS. Only periodic cleaning is required. You may need to replace filter cartridge only if it is physically damaged.
Ink temperature controller
Ink is a mixture of pigments and solvents. The solvents are volatile in nature and have a tendency to evaporate quickly. Solvent evaporation from ink in gravure and flexo presses occurs due to:
• Rise in ambient temperature which triggers evaporation of solvents
• Heat addition by film coming out of dryer getting in contact with ink
• Friction between doctor blade and cylinder generates heat which is transferred to ink
• Pressure of the anilox roll on the print cylinder generates heat
The above factors also contribute to the increase in temperature of ink which promotes solvent evaporation.
Solvent evaporation: High temperature increases the rate of solvent evaporation. As the solvent evaporation increases, it results in,
• Higher top up solvent consumption leading to increased operating costs
• Under high temperature ink tends to thin out prompting the operator to add more fresh ink to get the desired print shade. This increases ink consumption.
• Due to continuous solvent evaporation, there is a high concentration of solvents in air resulting in strong pungent solvent odour in shop floor.
Poor print quality: Under high temperature, the ink in the gravure cells on the print cylinder tends to dry quickly before getting transferred onto the film. This causes missing dots resulting in poor print quality.
Valflow ink temperature stabiliser (ITS) is a shell and tube type heat exchanger. The warm ink passes through the inner tubes and chilled water circulates in the outer shell.
The temperature of ink is continuously monitored by a temperature sensor. As the temperature increases more than the set value, the temperature controller operates a solenoid valve connected to the chilled water line. As the chilled water flows into the ink temperature stabiliser, the warm ink loses heat to chilled water.
By maintaining the ink temperature, solvent to pigment ratio can be maintained and hence the viscosity can be controlled to an extent. Since solvent evaporation happens even at an ink temperature of 25o C, viscosity variation happens even at this temperature. Hence it is suggested to install a Valflow ink temperature stabiliser and later install a viscosity control system if required.
No. Valence doesn’t supply chiller along with the Valflow ink temperature stabiliser. Valence can help with identifying the technical specifications of the chiller required for this particular application.
The maintenance of Valflow ink temperature stabilisers is very easy. The heat exchanger needs to be cleaned periodically. Also, it is necessary to ensure the usage of clean demineralised water in order to prevent the choking of solenoid valve. Standard operating and maintenance procedures are given in our instructions manual.
It is observed that by using Valflow ink temperature stabiliser, there is a saving of approximately 25 to 30% in the top up solvent consumption. These systems offer a very attractive payback of about 9-12 months.
Since printed web goes through heating process at each colour station, it is recommended to install one ITS per station.
Print register control system
Register control systems are used to define errors in colour position and advance or retard the film or cylinder precisely to maintain position of each colour on the printing machine. This ensures perfect print registration.
A register mark with predefined size and shape is printed for each colour. The fiber optic sensors positioned station two onwards, measure the distance between two subsequent colours. An error signal is generated to advance/retard the film or cylinder, to achieve perfect registration.
The common types of registration marks include triangular and rectangular. The size is universal and predefined.
Several factors can contribute to misregistration. Some factors include, tension control, inconsistent substrate properties, impression roller hardness, ink and solvent properties, and film shrinking/stretching.
The control and power cables must be routed separately, properly grounded, and shielded to protect the system from electromagnetic interference.