Not long ago, the only real choice for creating a pad printing cliché was to chemically etch a steel plate. However, advancements with photopolymer technology and laser-based CTP systems have created more choices for pad printing operations to consider.
What are the Advantages and Disadvantages of Steel Clichés?
Steel clichés for pad printing continue to be the mainstay for very large runs, especially for automotive, medical or consumer electronic applications. The number one advantage of properly manufactured steel clichés is that they can last as long as one million impressions or more, which provides an advantage for very long runs where eliminating machine downtime to change out a cliché can make a substantial difference in production efficiency.
The primary disadvantage to steel clichés is the high cost and extended lead times required to manufacture them. Because steel clichés are chemically etched, most are not manufactured in-house.
What are the Advantages and Disadvantages of Laser-etched Computer-to-plate Systems?
When using a CTP laser system, the graphics are first generation, with no loss of resolution – unlike photopolymer or steel clichés where film is first needed to create the image. There are no film, developing or etching material costs. And, a main advantage is time. Laser-etched clichés can be made in three to five minutes.
The disadvantage of a CTP laser system is the upfront costs involved with setting up the system. A laser etching system can run several times the cost of setting up photopolymer cliché exposure, development and post-exposure/drying equipment.
YAG laser systems were the first generation of CTP laser systems on the market and are more expensive systems. However, one large advantage of a YAG laser system is the potential ability to perform industrial laser marking as well. In addition, there are C02-based laser plate making systems that have been recently introduced with lower price points that make the start-up cost much more affordable.
When using the YAG laser technology, aluminum-based plates are used. The advantage of the aluminum plates is that they are double-sided, so an image can be etched in both sides of the plate. However, they are non-magnetic, so additional sub-plates are typically used to properly seal the magnetic cup with the plate. The CO2 system plates are a steel-backed coated plate made of a special polymer. This provides the ability for the cliché to work with magnetic ink cups and provides a more durable plate.
What are the Advantages and Disadvantages of Photopolymer Clichés?
Photopolymer clichés are an excellent choice for short- to medium-sized runs – from several hundred to several thousand. The advantage of photopolymers is the relatively low cost and ability to have the clichés produced in-house with a relatively small investment. Quality images can be produced by using a film positive where the image is exposed and developed with a water or alcohol wash.
Several types of photopolymer cliché materials exist. There are single exposure materials that are only exposed once, using the image film; and there are double exposure materials that are exposed once with the image film, and a second time with a line screen film. Additionally, there are water wash and alcohol wash clichés, and different levels of quality are available in all the types. The key is to find the right combination of price and quality for the specific application.
The drawback to photopolymer clichés is their overall durability. They are wonderful for short to medium-sized runs, but would not be the best choice for runs of hundreds of thousands or over a million. The other concern with photopolymer clichés is the number of steps involved in producing a plate. The more steps involved, the more opportunity for error and for producing a low quality cliché. As with laser-etched clichés, having the proper training and equipment is essential in producing consistent, quality clichés.
As technology continues to grow and processes are perfected, what might be the best choice for manufacturing your clichés at present may not be the best choice two years from now. Therefore, it is wise to keep a continual pulse on what is happening with cliché manufacturing – today and in the future.