The history of electronic printers and printing systems is very recent. The first electric printer connected to a computer was developed in 1953, though it could only print text. Many advances followed, involving numerous companies. In the course of about 40 years (at the beginning of the 1990s), printers had become a common feature in any office and/or workplace, even entering most homes that had a computer. Nowadays, home printer prices have dropped so much that it is sometimes cheaper to buy a new printer than the inks (consumables) themselves. When it was attempted to implement these developments in industry, particularly for the continuous manufacture of serial products, the resulting technology transfer or development differed greatly, depending on the sectors involved. While inkjet technology played a pivotal role in the development of sectors such as the graphic arts or photography, other sectors continued to use traditional techniques owing to the difficulty that, a priori, such transfer entailed.
The use of inkjet technology in the ceramic sector occurred late and did not materialise in the ceramic industry until 1998, when the company KERAJET was established with a view to industrially manufacturing the first prototype inkjet machine, specifically designed for ceramic decoration.
Types of inkjet technologies
In comparison with other decorating systems, inkjet printing is characterised by the absence of contact between the substrate and the machine during the ink deposition process. Two technologies may be distinguished in terms of the ink supply mechanism for ink deposition: continuous inkjet and drop-on-demand inkjet.
Revolutionary product development process
To date, with the usual techniques, the product development process required having a designer who was an expert in ink separation and a developer who was an expert in the effects and mixtures of ceramic colours. They needed to devote themselves almost entirely to these activities, in an iterative colour and effect adjustment process in order to obtain the final prototype, with all the ensuing costs.
With this innovative technology, however, the development process displays clear differences, which translate into important cost savings and even changes in the roles and capabilities of the persons involved. The main differences are as follows:
- Changes in the tasks performed by the designer and product development technicians.
- Introduction of new calibration and colour management technologies.
- Reduction or suppression of industrial trials.
Particularly to be noted among the multiple advantages and innumerable possibilities afforded by this technology are the system’s ability to decorate to the edges of the products, independently of product size or perimeter shape, and the possibility of decorating trims with pronounced relief.
A further major advantage of this technology is the simplicity and speed with which customised products can be made for indoor and outdoor flooring and wall cladding.
Latest advances in piezoelectric technology
The latest technological advances in printing heads have also contributed significantly to the definitive implementation of this printing technology in the ceramic sector. Two advances stand out. The first enables the deposited drop size, which had previously been fixed, to be regulated. This considerably enhances the final result, particularly the sharpness, thus eliminating certain problems stemming from stochastic screens. This new type of screening is known as grey-scale stochastic screening.
The second advance addresses nozzle clogging, which has been a major problem to date and is mainly due to bubble formation (caused by entrained air with the exiting drops) and/or precipitation of solid particles (owing to lack of motion), leading to defects caused by inconsistent register. The latest printheads incorporate different patented technologies, in which the ink circulates continuously through the heads with a view to eliminating or largely suppressing this problem.
Information compiled and analysed in the study
The searches conducted in the frame of this study have allowed noteworthy information to be identified, and a series of companies and research projects of interest in the field of inkjet printing technology to be pinpointed. The searches targeted Spanish and European projects, and scientific articles and patents of particular interest to the ceramic industry.
At the time of publication of the report, which had been updated with the latest innovations presented at the Tecnargilla 2011 trade fair, 13 different companies offering inkjet printing technologies for the ceramic industry had been identified. A part of the study is devoted to a description of each of these.
The introduction of digital printing devices has clearly led to a revolution in ceramic production lines with regard to the process and the products by enabling any type of decoration to be produced in large or limited series, rapidly transferring the design to the ceramic substrate and allowing any type of structured material or size to be processed.
In the last ten years, attention has centred on integrating and adapting consumables and machines to the requirements of the ceramic manufacturing process. This has essentially all targeted aesthetic results, but the multiple possibilities that this technology offers allow further future developments to be envisioned. The development and application of new functional materials with special properties (physical, chemical, etc.) would lead to innovative ceramic products with multiple applications that could open up new cladding applications and novel uses for the ceramic sector, far beyond the traditional field.