Published in New England Printing and Publishing 2002  © Ron Ellis

 

Criteria for Choosing a Platesetter –

Choosing a platesetter can be a daunting task because the technology and products change so quickly. There are a number of criteria that are important when evaluating platesetters. Some criteria are basic such as imageable area and punch configuration. Other items take more thought and influence the type of plates and chemistry that will be used to produce plates. One of the most important questions has to do with what type of plate material you will use in your plant. After looking at platesetters many potential buyers conclude that this is in fact the most important issue. The choice of plates for your platesetter may be quite limited.

As you can see by looking at the list in the sidebar many of these questions are related to the plate material that can be run through the platesetter. The plate material that you run will have a big impact in terms of how much it costs to make a plate, in terms of processing. For example hidden costs such as baking ovens and silver based chemistry and processors make the cost of each plate material, as well as the initial installation more expensive.

Right now platesetters are split between visible light lasers and thermal lasers. The choice of the laser dictates the type of plate material that can be used with the platesetter, and also has an impact on cost, productivity, and quality. If you are a printer that works in multiple markets, such as both commercial and web, balancing these needs can be tricky.

Visible light lasers expose a photosensitive coating. The coating may be a photosensitive coating, or may be a photopolymer.  Photosensitive plate technology involves a silver plate that typically provides excellent press performance, and is compatible with all visible light lasers. Quality levels with this type of plate are perfect for commercial applications (line screens up to 250 lpi) and run length for this plate is over 100 and can be as high as 100,000-300,000.  Processing of the plates involve the use of heavy duty chemistry and requires silver reclamation or recycling. In addition, visible light devices require handling in a light safe environment, meaning you need to load plates in a safe or dark room, or else purchase an autoloading option that allows you to load the plates in a darkroom and then safely transfer them to the platesetter.

Photopolymer technology is used in markets such as the newspaper and cold web. It has quality levels that are below that of silver and thermal. One benefit of photopolymer is that it can use safe aqueous chemistry which is attractive but it is limited by its low resolution and quality levels.

Many of the newer visible light devices are using violet diode lasers. These lasers are similar to the lasers used in CD and other consumer level technology. These lasers cost less and are faster, and are incredibly durable, and unlike many of today’s lasers have the potential to outlast the platesetter. (most of the older devices are using red laser diodes or ultraviolet lasers)  Violet laser diodes are becoming popular and are resulting in dramatic price drops in visible light platesetters.

Thermal technology is used primarily in commercial and high quality applications. Thermal uses much safer chemistry and has the potential of requiring no chemistry other than a water rinse. The plates are coated with a heat sensitive polymer coating. Thermal plate quality is high and the resulting plates have harder dots due to less light leak issues on the coated surface of the plates. With these benefits you may wonder what some of the drawbacks are? For long run jobs heating and baking ovens may be required. Also the plates and platesetters are also more expensive than visible light plates and platesetters. The plates may be as much as 40% more than analog plates. However thermal does have a future. The chemistry issues alone guarantee thermals future. As technology improves and becomes cheaper, and as a larger market buys thermal plates the prices should drop, making this technology more affordable than ever for platesetting applications.

Polyester platesetters are a whole separate issue, because many film imagesetters can also run polyester plates. Fewer metal platesetters can run polyester plates and film, although some can. Polyester can be an alternative for smaller printers who are looking for an alternative to expensive computer to plate systems, although applications are limited. Many printing companies will keep some type of film capability as they upgrade to computer to plate, even if it is just an old small format imagesetter for the occasional job that requires film or manual stripping. It is also possible to scan in film via copydot or scan linecopy, however these methods have the potential for producing an unwieldy and complex workflow.

At this point there are numerous choices for platesetters on the market, and they tend to be skewed towards small commercial printers, large commercial printers, general web printers and high volume web printing applications. There are a number of affordable 4 up devices on the market and the mid range market is growing. 8 up devices are also becoming more affordable. With the poor economic conditions it is a buyers market right now.

Typically when evaluating platesetter characteristics such as size, run length, resolution, imaging speed, as well as the biggie – cost – will help limit the number or potential platesetters you will need to evaluate. Developing a spreadsheet matrix with the selection criteria as well as associated plate costs can help you see all the possibilities and determine which platesetter is right for you.