Few people today remember who produced the first industrial printing machine that could do away with the long manual process of making printing plates. In the meantime, it was also the good old Heidelberger Druckmaschinen with its legendary model GTO. Today we will look back at this curious configuration, which became the forefather of today’s digital machines.
Heidelberg GTO (1972-2014). Part 1. A Printing Press From The Guinness Book of World Records.
Part 2. Prerequisites for the emergence of Computer-to-press technology
In 1990, the GTO printing machine base, proven for two decades, became the basis for another interesting configuration. Its appearance was predictable because of the imperfect plate process. The only question was when, by whom and how it would be realised. But first it is worth to tell about the prerequisites of its appearance.
The problem of the printing plate
Since the very appearance of offset printing, the most problematic and unpredictable issue has been the question of making printing plates. For decades, the process remained the same: first exposing the film, then exposing the plate. Only the technology has differed.
In addition to plates with a copying layer based on ortonaphthaquinodiazide compounds, known to most users of offset printing, bimetallic, trimetallic plates, plates based on larch gum, and even plates based on silver-containing compounds were developed for newspaper printing. But they all had the same flaws.
The problem of the copy layer of the plate
Why was the analogue process so unpredictable? In each of the intermediate preparation processes, the influence of human error was added. With photographic film, as with the plate, the reaction of the copy layer varied depending on the exposure, development, and the operator skills, of course.
If the film was slightly overexposed or underexposed, it immediately affected the size of the raster dot. If the developer temperature was changed, the veil area also changed. The operator, who exposed the plate, received a photographic film with an unpredictable result. In addition, the printing process itself depended on the skills of the operator.
That’s why many companies have been racking their brains on how to reduce the time it takes to make a plate, and more importantly, how to standardise it.
So, in 1990, on the basis of the long-suffering GTO printing machine, Heidelberg, in cooperation with the American company Presstek, demonstrated the FIRST truly DIGITAL PRINTING MACHINE IN THE WORLD. It was Heidelberg GTO 52 DI.
Appearance of a new star
Externally, the new machine did not differ much from the usual GTO. But inside it was very interesting. As in the case of the basic prototype, the new model could be equipped with both numbering and a perfecting device. It was available in four- and five-colour versions. Each print unit had its own laser head that exposed the printing plate.
There was no dampening unit in the machine, as Presstek had developed aluminium-based waterless offset plates specifically for this machine.
In addition, each of the machine’s ink units was thermostatically controlled. Maintaining a temperature of 25 degrees Celsius during printing was a necessity for these waterless plates. And the preparation of the single bit file for the laser head was handled by Linotype-Hell’s Delta RIP.
The print quality was excellent. This is confirmed by those rare impressions made on GTO DI lying on my desk right now. The quality was as good as standard offset process, but much more predictable. It had a short print life of about 10-15 thousand impressions, but it was sufficient for short runs.
A truly revolutionary solution was the possibility to apply the technology of making the printing plate inside the machine. It was done for the first time in the world in an offset printing machine.
In this way, Heidelberg eliminated potential errors at the prepress level.
The problems of the analogue plate making process were eliminated.
The printing process could be easily calibrated in full.
But the most important, the time to produce an offset print was reduced from a day to an hour.
Disadvantages of the new technology
The speed of 12,000 sheets per hour was excellent for accidental printing at the time. Yes, the printer removed and inserted the plate by hand. Yes, special waterless offset inks were required, which were twice as expensive as conventional inks. And the plate itself was not cheap, three times more expensive than a standard one. It was assumed that due to the increased urgency of order fulfilment the printing house would sell the products at a higher price.
But the most serious problem was the price of the machine. In fact, the print shop was buying 4x or even 5x exposing devices together with a conventional printing machine.
What else? Additional accessories that could be used online – such as numbering, imprinting, creasing and sheet cutting with the numbering shaft drive – have not been automated, and negated all the advantages of the new technology.
Heidelberg quickly realised the disadvantages of the new machine, but was not about to give up on the Computer-to-press technology that had been developed.
Subsequent development of computer-to-press technology
The GTO-DI machine was taken out of production in 1995. Instead, two models were launched on the market.
– Quickmaster QM46-4 DI with the Presstek waterless offset printing plates, but based on polyester (the moulds were rolled up). The same technology of dry offset.
– Speedmaster SM74 DI, which could be ordered in four-, five-, and even six-colour versions, with a varnishing unit. Each unit had its own exposure unit. Thus, the machine could handle both regular plates and waterless offset plates. Over time, when Presstek went bankrupt, the owner began to remove the exposure units and work on conventional plates.
The offset Computer-to-press technology was phased out due to the active development of modern Computer-to-Plate technology. Presstek still tried to sell its plates for some time. This is how Ryobi 3304 DI and Presstek 52 DI appeared, which was also produced under the Dainippon Screen logo. But the capabilities of the polyester-based moulding material were severely limited, and in the first half of the 2010s, Computer-to-press technology was modified.
Today its heirs are digital printing machines from HP, Canon, Konica Minolta, Xerox, Orient, Kodak, Landa, and many more, which have applied fundamentally different approaches to exposure inside the printing machine itself. But the pioneer was the Heidelberg GTO 52 DI machine, to which we must pay tribute.
We invite you to take a look at the video to see what this machine looked like in operation.
Used pictures:
Linotext, Cupertino CA, USA
Open sources
