The next generation of tile making will lead to increasingly sophisticated ceramic surface solutions, according to Joe Simpson.
Over the past decade, porcelain slabs have transformed the ceramic tile marketplace. The impact has been so profound that specialist distributors have emerged that focus on thin porcelain and nothing else.
Apart from weight, these tiles, which come in thicknesses from 3mm to 6mm, offer a range of advantages including installation over existing floor or wall coverings. This eliminates the need for ripping out existing finishing materials in renovation projects, saving labour and logistics costs.
They are strong yet reduce material consumption which benefits the environment. They can also be easily cut with a wet saw, and in some cases, (easier with non-reinforced slabs) using a standard hand-help glass cutter.
There are currently five main technologies used to manufacture thin tile. The Lamina process using System equipment (System itself manufactures Laminam tiles); the Continua process using Italian-made Sacmi equipment; the Supera system from Siti B&T; double-pressed or dust-pressed technology that loads powder into the press to produce a thin tile; and Lamgea, the new kid on the block (also developed by System).
Typically, Lamina tiles are 3mm thick and are produced in 1,000 by 3,000mm or 1,200 by 3,600mm slabs. Continua tiles are 3mm thick for walls and 4.6mm thick for floors.
Supera produces large ceramic slabs measuring 1,200 by 3,600mm that are cut into smaller, modular sub-formats; such as 600 by 1,200mm, 300 by 600mm or 300 by 900mm. Thicknesses usually vary from 5mm to 25mm, depending on the application. Large format dust-pressed tiles, essentially produced using conventional porcelain production presses, are typically 4.8mm thick, and not less than 4.5mm thick.
Most of these processes can produce tiles that are available with, or without, reinforcing mesh on the back.
Thin porcelain technology has taken off in a big way in recent years, with many leading manufacturers making large investments in this type of machinery.
For instance, Cotto d’Este’s Kerlite collection is manufactured using the Lamina process, as is Lea Ceramiche’s Slimtech Re-Evolution. Refin’s Skin 4.8mm slim porcelain stoneware is made using dust-pressed technology, and offers the same technical characteristics as standard thickness porcelain tiles.
Why use thin tiles?
Environmental benefits: Thin tiles use up to 70% less material than regular porcelain tiles. Thin porcelain tiles also use less energy during manufacture.
Lightness: Thin tiles can be used for incorporating large format tiles onto the wall, previously not possible. Being lightweight, they are cheaper to transport.
Project speed and cost: Large, slim tiles can cut the time needed to strip off the previous finish and prepare well ahead of the new tiles being mounted. This can ultimately save time and money.
Continua and Continua+
Continua+ is the latest generation of the revolutionary Continua system developed by Sacmi. It is an innovative compaction technology that redefines productivity for large size tiles. Continua+ allows the manufacture of porcelain slabs and tiles in a wide range of sizes and thicknesses, decorated both on the surface and in-body, at far higher output rates than traditional vertical press processes.
Sacmi offers Continua+ lines with four-colour powder-based digital decoration and “on the move” tile cutting. At the heart of Continua+ is a continuous compactor that can form slabs that are stronger and denser than using traditional vertical pressing.
Compaction occurs by way of two very stiff motor-driven belts. The powder is deposited on the lower belt and carried inside the machine where it is subjected to the combined action of two belts and two compaction rollers. Non-deformable containment buffers limit lateral movement.
The cutting machine incorporated into the line allows manufacturers to produce a full range of sizes simply by adjusting a few settings. This, and other modern tile production systems also benefit from advanced digital quality control systems, such as those developed by Surface Inspection. They offer highly accurate, automatic, digital product inspection scanning pattern, dimensions and planarity.
Iris, Ariostea, GranitiFiandre, Co-Operativa Imola, Iris, Fincibec, RAK, Nord Ceram and Steuler are just some of the big tile names that have invested in Continua technology.
Allied to smart systems and patented technologies, Supera by Siti B&T is flexible and versatile in terms of its tile thicknesses. It is also fast, with an average daily production capacity for each line of around 9,500sqm depending on thickness.
Supera offers clear financial benefits as well. Start & Stop on-demand hydraulic power generation is claimed to reduce energy consumption by up to 30%. It can also handle up to 10 surface textures at the same time, while significantly reducing production waste.
Rather than just a pressing technology for large-size tiles and panels, Supera is a complete production line with cutting-edge technology. It can produce ceramic slabs up to 1,200 by 3,600mm…and their sub-multiples…in a wide range of thicknesses (from 5 to 25mm).
To illustrate how tile production technology is constantly improving, it will soon be available in a massive 1,600 by 4,800mm version – using 33,000 tonne pressure – which will allow economic production of the increasingly popular 800 by 800mm tile format.
With Supera, Siti has reproduced the advantages of traditional pressing on a discontinuous belt press. It is equipped with three hydraulic pistons designed to guarantee uniform shaping on the edges and splitting of the panels to minimise deformation during pressing. A system of mobile powder containment plates solves the problem of side waste, one of the major challenges facing technicians working with large sizes.
The press is also equipped with a breathable system that allows for effective venting through a semi-porous membrane. This leads to greater production efficiency.
A key feature of the Supera line is XXL Green Cut, a cutting machine for unfired ceramic slabs up to 4,000 by 1,350mm equipped with a transverse and longitudinal row of disc cutting units to cut the slabs in both directions and at positions that can be set via the touch-screen control unit.
Other technical features include the high-precision XXL Deepmotor Cut score-and-snap line for cutting fired and unfired panels, the XXL Polishing machine, the XXL Wet Squaring machine, the high-speed DRY Squaring Speed machine which allows for considerable energy savings, and the Hi Coat protective treatment.
The system offers aesthetic potential by exploiting digital decoration technology from Projecta Engineering; and material finishing from Ancora, both Siti B&T Group member companies.
The latest major player in this market is System. System’s Lamgea is a mouldless press, capable of manufacturing slabs up to 4,800 by 1,600mm using standard atomised porcelain powders. It is possible to create any effect on the slabs, even structured surfaces with a relief up to 2mm, digital decorations and 3D effects.
Since the belt slides on the press, users can create different structures on a 16m long slab surface. This means that three concurrently-produced slabs, each 4,800 by 1,600mm, can each have different designs.
Lamgea is designed to reach a force of 30,000 tonnes and can produce panels such as 1,600 by 3,200mm or 1,200 by 2,400mm. These slabs can be anywhere from 3 to 20mm thick.
Each Lamgea plant is controlled using Copilot touch screens that have an intuitive interface for controlling the day-to-day production process of the line and signalling any necessary maintenance work in advance.
For manufacturers seeking a complete turn-key solution, Lamgea can be paired with a high definition (400 dpi) Creadigit BS digital printing system.
We have to look back to the launch of Laminam (also known by many other proprietary names) to really trace the reason for thin porcelain’s current popularity. These 3mm thick, fibre-reinforced, sheets, initially 1,00mm by 3,000mm, marked a step change in the perception of just what we mean by a tile: a process that has just led the American tile industry to coin a new term “gauged ceramic panels” in an attempt to provide some classification clarity.
But while it is easy to get carried away by just how large these ceramic tiles/sheets./slabs/panels are, fundamentally, they still rely on the same basics, in terms of body preparation, pressing and firing as smaller tiles.
The first step in the manufacture of thin ceramic slabs is the reception and storage of incoming raw materials. The basic ingredients that go into a finished tile are clays, sands and feldspars. These are routed to separate storage and undergo rigorous quality checks to ensure they comply with each company’s specified standards.
When the time comes for their use, each raw material making up the required mix is checked for quality and consistency by an automatic computerised weighing and dispensing system that will deliver the exact amount of each ingredient.
The raw materials are then conveyed to the grinding bay, where they are fed into a continuous mill. Water and pebbles – a grinding aid – are added to the mix. The end product is a very fine paste, usually with a moisture content of around 30%, often referred to a “slip”.
This “slip” is then forced at high pressure into a drying chamber where it is dispersed as a fine spray. The resultant dry powder is known as atomized dust. This fine-grained dust is the ideal consistency for the subsequent production steps, allowing the material to move smoothly through the next phases. From the drying chamber, the dust is taken by conveyor belt to storage silos until needed on the tile production line.
When required, the atomised dust, now with a moisture level of around 5 to 6%, is loaded into a hopper, sieved to remove any impurities, and delivered to the production line. Depending on the product being manufactured, additional materials can be added at this stage so that the finished tile surface will feature the required effect.
Then comes the critical pressing phase, a key moment in the tile-making process. In traditional production, this features an hydraulic press and its control unit. In the Laminam process, the sheet steel press exerts pressures of up to 15,000 tons to make the 3 by 1 metre ceramic slabs.
The press has a matrix on the upper part, and a conveyor belt below. The conveyor belt carrying the dust-mix is pushed upwards during the compaction or pressing phase by a rectangular piston. During pressing most of the air contained between the granules of the dust-mix is expelled. The result is a smaller, highly compacted tile body.
This is in contrast to traditional dust-pressing technology which uses an hydraulic ram to compact dust contained in a mould or die. The new pressing method does away with the die and so avoids most of the stresses caused by lateral thrust against the sides of the retaining die.
As noted earlier, Continua, Supera and Lamgea use a belt-based pressing system.
After pressing, whatever the system, most tiles/panels then enter a gas-fired drying chamber, that reduces the moisture content of tiles/slabs to residual humidity of around 0.5 to 0.6%.
Decoration on these unfired tiles can be achieved in many ways, and often has a combination of technologies including rotary silk-screen printers, of which Rotocolor is the leading brand.
These printers are used to apply background dyes, a range of graphic designs and protective surface glazes. Today they are usually combined with digital ink-jet printers. These feature multiple print-head bars; with each bar able to carry a different colour pigment.
The ink-jet printer operates like a plotter making repeated passes over the slab as required. Digital decoration ensures high-resolution patterns or pictures. There is no limit to the graphic designs possible.
Once decorated, the thin ceramic tiles/slabs are fired in gas kilns for around 35 to 40 minutes at temperatures that reach around 1,200 to 1,210°C. After firing, a carefully-controlled cooling phase ensures that the finished slabs are perfectly flat, exactly the right size and do not have internal stresses.
Most equipment manufacturers now use highly accurate digital scanning and weighing technology, along with robotic sorting and packing lines to minimise breakage in transport.
The end result is a range of new surface materials that are taking ceramic “tiles” into completely new areas – façades, worktops, furniture manufacture, signage, tunnel linings, etc – that were, quite simply, beyond reach only a decade or so ago.
And don’t expect the pace of production evolution to slow down any time soon.