Centro Ceramico15   Marzo   2017

A study on large ceramic slabs

The Centro Ceramico and its partners from the IPERCER project are analysing five stages of tile manufacturing

Over the last few years large ceramic slabs have brought about a true revolution in the ceramic industry. This product type has engendered new technological challenges in the fields of production process, its related energy aspects and customisation of finished products
And that's exactly why, in the framework of the Emilia Romagna regional call for tenders POR-FESR 2014-2020, Priority Axis 1 Research and innovation, Action 1.2.2, the IPERCER project has been funded. The research will concern the Centro Ceramico (Bologna), the Institute of science and technology for ceramics CNR-ISTEC (Faenza, RA), the University of Bologna through the Interdepartmental centres for Industrial Research CIRI EC (Building and Construction) and CIRI MAM (Advanced mechanics and Materials), the company NIER Ingegneria S.p.A. (Bologna) and, for promotion activities, Confindustria Emilia-Romagna Research and Confindustria Ceramica.
The project will also see the participation of major ceramic slabs manufacturers - Gigacer S.p.A. and Panaria Group S.p.A. – and producers of manufacturing plants for large slabs - SACMI s.c.a.r.l. - as well as Reverse & Quality s.r.l. engineering consulting firm, specialised in measuring methods. The contribution of these companies, not directly financed by the project, is to favour the technological transfer of the different research steps at an industrial level.

The behaviour of the atomized powder during deposition and compaction
The atomized are distinguished according to their fluidity, density, porosity, grains and compacts mechanical properties, and according to humidity, granulometry, agglomerates shapes, additives and process parameters (fig. 1). In order to verify the applicability of existing mathematical  models and  examine their effectiveness and accuracy, computer simulations are being set up (using combined DEM, Discrete Element Method, / FEM, Finite Element Method approach) designed to duplicate the experimental results obtained in laboratory on atomized powders (fig. 2). The targets are: to gain interpretive schemes depicting the process of atomized powder deposition and compaction (dry and green cohesion mechanisms), also examining the impact of additives; and to approve an operating protocol for the rheological dinstinction of the atomized.

The behaviour of mixtures during firing: warpage and their modeling
The behaviour of porcelain stoneware mixtures during sintering and cooling is being analysed, with special attention given to mechanisms that can cause residual deformations in finished products. The aim is to quantify the physical properties and phase transitions causing residual deformations in large ceramic slabs, through experimental techniques. A protocol for the esvaluation of viscosity of porcelain stoneware mixtures at high temperature  is also under study.

Post-firing: plant modeling and optimization of cut, split and polishing phases
Sustainable manufacturing solutions to optimize ceramic slabs cutting processing are being developed to promote a sustainable manufacturing process. The interventions envisage a general rethinking of the finish and plant automation process, a redesign of some operating groups to reduce actual loads and consumption, but also breakage, machine downtime, flaws and waste. In particular, thanks to the introduction of advanced simulation techniques, many design decisions to improve the existing plants both at a structural and functioning level are being developed (fig. 3).

Improvement of energy efficiency
In terms of energy, particular attention will be devoted to firing and post-firing processing. Current solutions enable to monitor consumption and process parameters in real time and, through the individuation of significant energy indicators, a tool for an optimum management of firing and post-firing process in terms of energy will be developed. Field-testing, starting with kiln and process analysis, will enable the development of models for continuous monitoring for optimum energy management of the analysed processes.

Methods of measurement and control
One of the specific activities the project entails is the development/implementation of new methods of off-line measurement  of ceramic slabs. The particularly big dimensions of large ceramic slabs require innovative yet still reliable measuring systems. It is necessary to use testing techniques designed to guarantee quality control and certification of the finished product. We are currently analysing the results obtained with a horizontal plucometro (dimension testing equipment for ceramic tiles), portable 3D measuring arm and coordinate measuring machine (CMM) (fig. 4). The measurements (length/width, rectangularity, straightness of sides, surface flatness, etc.) are carried out according to UNI EN ISO 10545-2 “Determination of dimensions and surface quality of ceramic tiles”. The aim of this activity is to define a measurement protocol with the new methods, in compliance with current legislation.

The project IPERCER has set itself ambitious targets and at the same time is a great opportunity for examining issues which are important to tile manufacturers. The adoption of solutions such as modeling and numerical simulation of products and processes, and a rigorous experimental approach,  guarantee that the results of the research can actually be used in the industrial world.

Process innovation for a sustainable ceramic industry
IPERCER project addresses the ceramic tile industry, in particular large format porcelain tiles manufacturers. By studying and implementing at an industrial level a series of innovative tools, it faces the technological and energy-linked challenges  brought about by increased production and demand of these new products.
It will therefore be possible to optimize the quality and performance of the finished product, through rationalization of production and improvement of production efficiency, both in terms of technology (improvement of compaction, firing, methods of measurement, etc.) and energy saving (reducing consumption). We want to provide ceramic tile manufacturers with tools to “design” the features of the finished product according to process parameters, so as to support companies during planning stage, control, and process monitoring. The  project aims at:
1) setting up a descriptive model of the behaviour of atomized powders and compacts during deposition and compaction of large format tiles;
2) modelling the behaviour of large ceramic slabs during firing, with particular regard to residual stresses;
3) carrying out an energy analysis of the firing process, finding solutions to improve its efficiency, creating a platform for the management and control of energy consumption strictly linked to each phase transition of matter;
4) improving energy saving during the cutting process through a system of analysis, monitoring and systemic energy management, with a complete and detailed overview on consumption and verification of trends in real time;
5) setting up an off-line measuring system in order to assess dimensions and surface flatness of large slabs, while at the same time define a series of criteria for on-line control of the same measures;
6) setting up guidelines and a measurement protocol of dimensions and surface flatness of large slabs.