A wall mounted steam humidifier ideal for compact digital print areas
from Humidity Solutions
Low humidity and the often linked problem of static can cut productivity; controlling them is a cost effective way to improve performance.
High above the heads of anyone who visited HP or Heidelberg at drupa were humidification systems. Technotrans UK managing director Peter Benton says: ‘it is significant that HP and Heidelberg put [humidification] in for drupa. They wouldn’t do that unless they needed to and if they are prepared to do that for ten days at a show why won’t more printers do it?’
Printers may be reluctant to accept that productivity problems caused by low humidity such as misfeeds and misregistration have anything to do with the their operating conditions, and instead blame the machines and materials. Humidity Solutions managing director John Barker is often asked to visit printers by suppliers to resolve issues. Some firms may choose to soldier on with unaware of the magnitude, causes and cost of the problem. Dave Marshall-George, UK area sales manager for Condair, (whose Draabe division supplied the Heidelberg and HP systems at drupa) says ‘It is something people put up with and unless they are monitoring wastage and downtime it is hard to quantify; there is a lack of analysis’.
One reason that Heidelberg and HP may have installed humidification at drupa is that both are leading the charge in the quantification and analysis of their equipment’s productivity. Tools within Prinect and Print OS are geared towards getting as close as possible to the theoretical throughput of a press. Static and humidity control firms welcome this development as helping to identify the problems.
Get in the Q zone
‘Temperature and humidity control is especially important for digital print, says Humidity Solutions’ Mr Barker. ‘We have been working with Konica Minolta and HP on helping to get operating conditions into what they term the Q zone (Q for quality), which is relatively narrow – 18-25C and 45-65% RH. Without some sort of control you will be outside of those conditions for a large part of the year. Our aim is to create stable humidity every day of the year. Unless you have humidification you will always be operating below the optimum and not get the best out of your equipment. The payback can be very quick. We have seen instances where it is a few months.’
Ripe Digital based in Corsham, Wiltshire, an HP Indigo customer with a 7800, is one example. ‘We were getting a lot of static and I was looking for solutions,’ says managing director Rik Penny. ‘We would find humidity would drop to 20% RH on a dry day. Since installing it we have fewer paper jams and materials such as self-cling and Folex go through the press better. We used to have run those first things in the morning. Now can run them at any time of day.’ Mr Penny assumed it would be expensive: ‘I thought it would cost ten times what it did. It cost us £1500, for that money it is a no-brainer.’
That amount is the lower limit, with prices rising depending on a number of factors including the type of system, size of the factory and number of air changes per hour. The system Ripe installed – a steam humidifier – may be perfect for many digital printers or digital print rooms within a larger factory. One reason is that the other technology, spray humidification, typically needs to be mounted 3.5 m above the floor to ensure the water droplets disperse into the air rather than wetting any machinery or materials. Spray systems are also more expensive to buy as they need water treatment to keep the system and staff healthy, starting at about £7000. While spray systems are more expensive to buy they are cheap to run, and offer the added benefit of providing cooling too.
Humidity is tied in to temperature; as air is warmed its relative humidity drops. This leads to greater problems in colder months with heating drying out the air. If you use air conditioning to control the temperature of your digital presses that may exacerbate things as the process by which heat is removed also removes moisture, which then needs to be added back in. One thing all the vendors agree on is that there’s no off the shelf option. Mr Barker says that: ‘getting the right system needs a site visit and planning. Lots of things will impact the success of humidification including the number of air changes per hour and these
will have an impact on operating costs.’
Getting ex-static
To an extent static and humidity are linked. Humid air is better able to carry static charges to ground, reducing a lot of static issues. However, in some instances static control will also be needed. ‘Even with humidity control in place you can still get problems with static such as paper jams, and not just on presses, you get it in finishing too, such as on folders,’ says CyanX managing director Richard Mawson, who supplies products to address both. The solutions are affordable; a disposable Ionix unit costs £140 and lasts a year. Static eliminating spray that you can apply to localised static problems is £15-£20 per bottle.
‘For a more permanent solution we would do site surveys with meters to measure humidity and static,’ adds Mr Mawson. Wide format printing is prone to static due a combination of factors including the imaging process itself causing static and the materials used holding a charge. Combined with the potential for static to impact image quality and damage printheads, it is especially important to address it in this sector. Fortunately it is inexpensive
to address.
Gary Hughes, global sales manager, Fraser Anti-Static says: ‘If static is a problem it is often cheaper to fit an anti static unit than it is for an engineer visit to identify the problem. For a 1.6 m wide flatbed the cost is £500-£700.’ The last word goes to Technotrans’ Mr Benton: ‘these are simple solutions that have a dramatic effect. People don’t understand the impact of static and humidity on productivity and think they can get away without them. Compared to the cost of a press it shouldn’t be an issue but often it is.’
In the material
Earlier this year Perspex Distribution started to sell a new foamed PVC from Palram that contains a static control additive.
‘Static is a huge issue, both for the staff handling the materials and print quality,’ says Perspex Distribution marketing manager Luke Martyn. ‘This is a solution that high volume printers have been crying out for. It can save a lot of time. If you’ve got to treat every sheet with an anti static then you need someone dedicated to that, which can take as long as the printing.
‘Unfortunately we can’t say that we have solved static for all materials but as it is an additive in the sheet, maybe it could be added to other materials.’
