Final ReportSummary - NOVAPRESS (Development of a Non-destructive Sensor to Determine Density Gradient of Ceramic Tiles During Pressing)
The industrial techniques used for ceramic tile production and ceramics in general are a complex series of chemical and physical process that transform a mixture of powders into a complex shaped product having remarkable physical and chemical properties. This is achieved by using know-how, complex machinery and systems that continuously evolve over time according to the changing requirement of the market.
As well articulated by Pierluigi Ponzoni in the preface of Acimac's handbook for raw material preparation and forming of ceramics tiles, one of the fundamental aspects concerning to obtain the maximum yield in terms of quality and quantity from a production plant operation is linked to a close control of all process variables.
The most common defects such lack of calibre, warpage, delamination typically arise during the pressing stage, leading to losses or at least down-grading of final products. Density gradients are usually caused by poor die design, bad practice and/or unsuitable particulate materials, with the resultant poor flow ability impacting on die filling uniformity. At present, these faults go undetected until the pieces have been fired, rendering them scrap, which is difficult to recycle and often sent to landfill. Tile factory waste is in a well regulated situation of about 5 %.
Although remarkable improvements in the control of ceramic tiles production occurred in both end of the manufacturing process (raw materials selection and firing), there are still room for improvements in the middle ground, e.g. the control of the pressing stage. Detection of faults during pressing allows efficient recycling the waste tile material and using it for pressing again. Few systems are available to control green ceramic tiles off line and on line.
In this project, LEMA, a well known Italian manufacture of presses, moulds and punches for the production of ceramic tiles lead a consortium of small and medium-sized enterprises (SMEs) and research and technology development (RTD) performers aimed to produce an innovative system in which the control system in installed directly in the press dies.
The project successfully delivered two prototypes to be used off the press which contain the necessary technology that enable also to be installed on the press. The technology has been patented. Successful development of this technology into the press will make possible an immediate detection of density gradients during pressing. Using this information engineering, a reliable feedback control acting directly on the hydraulic system of the press or the powder feeding system can be designed. This will result in automatic correlation of the pressure profile / distribution of the powders into the mould to deliver well-pressed tiles.
The prototypes are expected to be presented at the forthcoming Tecnargilla exposition, to be held in Rimini in September 2012.
Project context and objectives:
The occurrence of density gradients in ceramic tiles during pressing is the primary cause of differential shrinkage, lack of calibre, delamination and warpage which lead to losses and/or down-grading of the final products.
Density gradients are usually caused by poor die design and/or unsuitable or poor flowability of particulate materials, which hinder a uniform die filling or unbalance of pressure in the press due to a poor set up. At present, these faults go undetected until the pieces have been fired.
The NOVAPRESS project aims to develop an in-situ sensor to be placed on the dies or press frame or immediately after the press that enables measurement of the density of ceramic tiles during pressing by using ultrasonic pulse velocity (UPV) measurement. The NOVAPRESS system will allow the rejection of bad quality tiles to occur before they travel down the glazing / decoration time and onto the energy-consuming firing process. Also after glazing / decoration and/or firing, the recycling of the tile body will be more difficult and the glaze wasted. Considering that the cost of the glaze is probably an order of magnitude higher than the cost of the body, a timely detection is essential for a potential in-line reject system.
Other projects have attempted to address the problem of on-line measurement of the density of green ceramic tiles, for instance using non-contact ultrasonic transducers placed in the convoy belt at the exit of the press. However, this air coupling system showed a poor level of signal to noise ratio caused by:
(i) ultrasound attenuation in the air gap separating the sensors; and
(ii) by environmental conditions typically encountered on ceramic tile factories such as dust and vibration in the belt.
Online contact, as developed in the NOVAPRESS project, will enable an improved acoustic coupling between the transducers and the green tile surface. The contact method is expected to not affect the quality of the surface of the unfired tiles because it is done during the forming stage and to not slow down the production line.
Successful development of this technology will make immediate detection of density gradients possible during pressing. Using this information, engineering a reliable feedback control acting directly on the hydraulic system of the press or the mechanism for loading the powder into the dies can be designed. It will also shorten the time needed to set up the press when the die is changed. This is an important feature for SME tile manufacturers that rely on production of small batches to increase flexibility and compete with the larger manufacturers.
NOVAPRESS focuses on the development of a novel sensor system as enabler of promoting innovation on the well established sector of pressing of ceramic tiles. The sensor system will assist in maintaining the competitiveness of the European manufacturers of machinery and equipment for the ceramic industry AND European ceramic manufacturers through a knowledge based technology lead. Waste of materials and energy will be reduced through improved control of manufacturing processes, which will be particularly beneficial to SMEs in their continual quest for survival by increasing efficiency and widen their client base to include new industrial sectors.
Project results:
The NOVAPRESS project is divided in eight work packages (WPs), in which WP8 is dedicated to project management. The first three WPs and associated deliverables (D1 - D6) were completed in RP1, while the remaining WPs and deliverables were completed by 30 June 2012.
In WP1, the specifications and common targets confirmed and the first preliminary tests carried out. In WP2 and WP3, the hardware (die and sensors) was developed in parallel leading to the preparation of a working pre-prototype dies which was demonstrated. However, after a detailed risk analysis, the steering committee decided to develop the system by dividing the work plan in three distinct parts:
(1) development of an off the press off the line system;
(2) development of an off the press on line system; and
(3) design a roadmap to achieve the on the press on line system.
The outcome of the two first parts of the development plan would allow creating the relevant intellectual property (IP) portfolio and production of commercially available system that would enable to reduce the risk and increase the revenue stream before starting the inclusion of the sensors system inside the press. Accordingly, WP4 and WP5 were dedicated in building up the hardware and software control of the off the press technologies to control the density off the line and on line with roller sensors.
The results obtained to date have evidenced the feasibility of the 'in-contact (UPV) methods' for in situ density measurements off the press with exceptional accuracy and without affecting the speed of the production line.
A demonstration of the two off the press technologies (off line and on line) was successfully carried out in the final review meeting held in TopCer on 31 May 2012 and reported in Deliverable 11.
Potential impact:
In line with the main aim of the project, to strengthen the competitiveness of the SME participants and to contribute to improving the tile sector competitiveness across the European Union (EU), the NOVAPRESS project is expected to deliver a novel method for measuring (and thus controlling) green tile density during manufacture. This method will itself be a commercial product directly exploitable by two participants (LEMA and ELEK) and would help retaining jobs as well as growing. The method was piloted in a tile manufacturer (TOPCER) which would like to improve productivity and reducing manufacturing cost and waste. TOPCER is already a client of LEMA, making the implementation of the results easier.
Apart improving the quality of the manufactured product (happy customer), reduce waste to landfill (happy environment). LEMA expect the NOVAPRESS system to be applicable to other less mature sectors than tile manufacturers, such as medical ceramic manufacture, drug pressing etc. opening up new high value markets for the SME participants and generating capabilities allowing them to enter the new markets.
The NOVAPRESS project is seen as making a short to medium term impact by allowing early detection of faults and so reducing the extent to which value-adding process steps are applied to scrap ware. The exploitation of the technology is not restricted only for the ceramic tile market, but is expected to applied for commercial press control systems used for producing other ceramic items such advanced ceramics and bio-ceramics.
The final stage of the development of the NOVAPRESS system involves the introduction of the sensors in the die or press and automatic adjustment of the pressure profile.
A total potential return of EUR 3.5 million in 3 years (based on increase revenue and cost reduction) is expected by the SME participating in the consortium vs. a total investment of EUR 1 million.
Socio-economic impact and the wider implications of the project so far
The European ceramic tiles industry records total sales of EUR 7.3 billion (source Cérame-Unie, 2010) and employs 110 000 people. Italy and Spain account for 85 % of European ceramic tiles manufacturing.
The EU (principally Italy and Spain) is still the only geographical area with a real export propensity, with 54 % of local production exported. In order to maintain the strong position of the European tile industry and to generate new market opportunities, innovative products and responsiveness to market needs are essential.
One of the main tile market trends currently is the increasing demand for large and thin tiles. The large size is preferred by architects due to visual effects they can create. These tiles must maintain high qualitative specifications regarding the flatness and appearance. In addition, development in construction regulations is causing a market pull for large size tiles that are used in cladding. Higher energy-efficiency of ventilated wall systems are also gaining importance. In these systems, large tiles are often used as a preferred cladding material due to both technical and aesthetic values. Ventilated walls can reduce the amount of heat that buildings absorb in hot weather due to partial reflection of solar radiation by the covering and the ventilated air gap and to the application of insulating material. Vice versa, in winter, ventilated walls retain heat. As a further benefit, the ventilated walls tend to increase the reflection of external noise. Suppliers to the insulation market argue that buildings offer the biggest opportunities for the largest decreases in carbon dioxide (CO2) discharges since buildings account for 40 % of total greenhouse gas emissions in Europe. It is anticipated that the improved energy efficiency measures should save one million tonnes of carbon per year by 2010 (equivalent to emissions from more than one million semi-detached homes). The first changes, to Parts F (ventilation) and L (fuel and energy conservation), came into effect on 6 April 2006.
The technical challenges producing these large tiles are significant, since the larger size multiplies the potential of faults in tiles. The occurrence of density gradients during pressing is believed to be the primary cause of defects occurring during processing, such as differential shrinkage, size variation and warpage (bending of tiles). Density gradients are usually caused by poor die design, bad practice and/or unsuitable particulate materials, poor flow ability impacting on die filling uniformity. At present, these faults go undetected until the pieces have been fired to a final product and they need to be reprocessed or disposed as waste. The technical issues have been limiting the introduction of the large tiles to the market. The percentage of the production is currently circa 1 - 2 % of the total European production (circa EUR 100 million). The market demand and the additional costs for larger tile manufacturers to adjust their mass production to the technology make the entrance of new SME tile companies specifically to this market very interesting.
The results to date have indicated that a contact and direct UPV measurement system is feasible and enables on-line density measurement of green tiles. The out-of-press system could be sold also for monitoring the density in other stages of the ceramic producing cycle (for example after firing or drying) increasing again the number of products potentially sellable.
Finally, the off the press off the line system can be seen as a lab test equipment alternative to mercury intrusion and/or the penetrometer.
Project website: http://www.ceramgroup.com/projects/novapress/index.html
As well articulated by Pierluigi Ponzoni in the preface of Acimac's handbook for raw material preparation and forming of ceramics tiles, one of the fundamental aspects concerning to obtain the maximum yield in terms of quality and quantity from a production plant operation is linked to a close control of all process variables.
The most common defects such lack of calibre, warpage, delamination typically arise during the pressing stage, leading to losses or at least down-grading of final products. Density gradients are usually caused by poor die design, bad practice and/or unsuitable particulate materials, with the resultant poor flow ability impacting on die filling uniformity. At present, these faults go undetected until the pieces have been fired, rendering them scrap, which is difficult to recycle and often sent to landfill. Tile factory waste is in a well regulated situation of about 5 %.
Although remarkable improvements in the control of ceramic tiles production occurred in both end of the manufacturing process (raw materials selection and firing), there are still room for improvements in the middle ground, e.g. the control of the pressing stage. Detection of faults during pressing allows efficient recycling the waste tile material and using it for pressing again. Few systems are available to control green ceramic tiles off line and on line.
In this project, LEMA, a well known Italian manufacture of presses, moulds and punches for the production of ceramic tiles lead a consortium of small and medium-sized enterprises (SMEs) and research and technology development (RTD) performers aimed to produce an innovative system in which the control system in installed directly in the press dies.
The project successfully delivered two prototypes to be used off the press which contain the necessary technology that enable also to be installed on the press. The technology has been patented. Successful development of this technology into the press will make possible an immediate detection of density gradients during pressing. Using this information engineering, a reliable feedback control acting directly on the hydraulic system of the press or the powder feeding system can be designed. This will result in automatic correlation of the pressure profile / distribution of the powders into the mould to deliver well-pressed tiles.
The prototypes are expected to be presented at the forthcoming Tecnargilla exposition, to be held in Rimini in September 2012.
Project context and objectives:
The occurrence of density gradients in ceramic tiles during pressing is the primary cause of differential shrinkage, lack of calibre, delamination and warpage which lead to losses and/or down-grading of the final products.
Density gradients are usually caused by poor die design and/or unsuitable or poor flowability of particulate materials, which hinder a uniform die filling or unbalance of pressure in the press due to a poor set up. At present, these faults go undetected until the pieces have been fired.
The NOVAPRESS project aims to develop an in-situ sensor to be placed on the dies or press frame or immediately after the press that enables measurement of the density of ceramic tiles during pressing by using ultrasonic pulse velocity (UPV) measurement. The NOVAPRESS system will allow the rejection of bad quality tiles to occur before they travel down the glazing / decoration time and onto the energy-consuming firing process. Also after glazing / decoration and/or firing, the recycling of the tile body will be more difficult and the glaze wasted. Considering that the cost of the glaze is probably an order of magnitude higher than the cost of the body, a timely detection is essential for a potential in-line reject system.
Other projects have attempted to address the problem of on-line measurement of the density of green ceramic tiles, for instance using non-contact ultrasonic transducers placed in the convoy belt at the exit of the press. However, this air coupling system showed a poor level of signal to noise ratio caused by:
(i) ultrasound attenuation in the air gap separating the sensors; and
(ii) by environmental conditions typically encountered on ceramic tile factories such as dust and vibration in the belt.
Online contact, as developed in the NOVAPRESS project, will enable an improved acoustic coupling between the transducers and the green tile surface. The contact method is expected to not affect the quality of the surface of the unfired tiles because it is done during the forming stage and to not slow down the production line.
Successful development of this technology will make immediate detection of density gradients possible during pressing. Using this information, engineering a reliable feedback control acting directly on the hydraulic system of the press or the mechanism for loading the powder into the dies can be designed. It will also shorten the time needed to set up the press when the die is changed. This is an important feature for SME tile manufacturers that rely on production of small batches to increase flexibility and compete with the larger manufacturers.
NOVAPRESS focuses on the development of a novel sensor system as enabler of promoting innovation on the well established sector of pressing of ceramic tiles. The sensor system will assist in maintaining the competitiveness of the European manufacturers of machinery and equipment for the ceramic industry AND European ceramic manufacturers through a knowledge based technology lead. Waste of materials and energy will be reduced through improved control of manufacturing processes, which will be particularly beneficial to SMEs in their continual quest for survival by increasing efficiency and widen their client base to include new industrial sectors.
Project results:
The NOVAPRESS project is divided in eight work packages (WPs), in which WP8 is dedicated to project management. The first three WPs and associated deliverables (D1 - D6) were completed in RP1, while the remaining WPs and deliverables were completed by 30 June 2012.
In WP1, the specifications and common targets confirmed and the first preliminary tests carried out. In WP2 and WP3, the hardware (die and sensors) was developed in parallel leading to the preparation of a working pre-prototype dies which was demonstrated. However, after a detailed risk analysis, the steering committee decided to develop the system by dividing the work plan in three distinct parts:
(1) development of an off the press off the line system;
(2) development of an off the press on line system; and
(3) design a roadmap to achieve the on the press on line system.
The outcome of the two first parts of the development plan would allow creating the relevant intellectual property (IP) portfolio and production of commercially available system that would enable to reduce the risk and increase the revenue stream before starting the inclusion of the sensors system inside the press. Accordingly, WP4 and WP5 were dedicated in building up the hardware and software control of the off the press technologies to control the density off the line and on line with roller sensors.
The results obtained to date have evidenced the feasibility of the 'in-contact (UPV) methods' for in situ density measurements off the press with exceptional accuracy and without affecting the speed of the production line.
A demonstration of the two off the press technologies (off line and on line) was successfully carried out in the final review meeting held in TopCer on 31 May 2012 and reported in Deliverable 11.
Potential impact:
In line with the main aim of the project, to strengthen the competitiveness of the SME participants and to contribute to improving the tile sector competitiveness across the European Union (EU), the NOVAPRESS project is expected to deliver a novel method for measuring (and thus controlling) green tile density during manufacture. This method will itself be a commercial product directly exploitable by two participants (LEMA and ELEK) and would help retaining jobs as well as growing. The method was piloted in a tile manufacturer (TOPCER) which would like to improve productivity and reducing manufacturing cost and waste. TOPCER is already a client of LEMA, making the implementation of the results easier.
Apart improving the quality of the manufactured product (happy customer), reduce waste to landfill (happy environment). LEMA expect the NOVAPRESS system to be applicable to other less mature sectors than tile manufacturers, such as medical ceramic manufacture, drug pressing etc. opening up new high value markets for the SME participants and generating capabilities allowing them to enter the new markets.
The NOVAPRESS project is seen as making a short to medium term impact by allowing early detection of faults and so reducing the extent to which value-adding process steps are applied to scrap ware. The exploitation of the technology is not restricted only for the ceramic tile market, but is expected to applied for commercial press control systems used for producing other ceramic items such advanced ceramics and bio-ceramics.
The final stage of the development of the NOVAPRESS system involves the introduction of the sensors in the die or press and automatic adjustment of the pressure profile.
A total potential return of EUR 3.5 million in 3 years (based on increase revenue and cost reduction) is expected by the SME participating in the consortium vs. a total investment of EUR 1 million.
Socio-economic impact and the wider implications of the project so far
The European ceramic tiles industry records total sales of EUR 7.3 billion (source Cérame-Unie, 2010) and employs 110 000 people. Italy and Spain account for 85 % of European ceramic tiles manufacturing.
The EU (principally Italy and Spain) is still the only geographical area with a real export propensity, with 54 % of local production exported. In order to maintain the strong position of the European tile industry and to generate new market opportunities, innovative products and responsiveness to market needs are essential.
One of the main tile market trends currently is the increasing demand for large and thin tiles. The large size is preferred by architects due to visual effects they can create. These tiles must maintain high qualitative specifications regarding the flatness and appearance. In addition, development in construction regulations is causing a market pull for large size tiles that are used in cladding. Higher energy-efficiency of ventilated wall systems are also gaining importance. In these systems, large tiles are often used as a preferred cladding material due to both technical and aesthetic values. Ventilated walls can reduce the amount of heat that buildings absorb in hot weather due to partial reflection of solar radiation by the covering and the ventilated air gap and to the application of insulating material. Vice versa, in winter, ventilated walls retain heat. As a further benefit, the ventilated walls tend to increase the reflection of external noise. Suppliers to the insulation market argue that buildings offer the biggest opportunities for the largest decreases in carbon dioxide (CO2) discharges since buildings account for 40 % of total greenhouse gas emissions in Europe. It is anticipated that the improved energy efficiency measures should save one million tonnes of carbon per year by 2010 (equivalent to emissions from more than one million semi-detached homes). The first changes, to Parts F (ventilation) and L (fuel and energy conservation), came into effect on 6 April 2006.
The technical challenges producing these large tiles are significant, since the larger size multiplies the potential of faults in tiles. The occurrence of density gradients during pressing is believed to be the primary cause of defects occurring during processing, such as differential shrinkage, size variation and warpage (bending of tiles). Density gradients are usually caused by poor die design, bad practice and/or unsuitable particulate materials, poor flow ability impacting on die filling uniformity. At present, these faults go undetected until the pieces have been fired to a final product and they need to be reprocessed or disposed as waste. The technical issues have been limiting the introduction of the large tiles to the market. The percentage of the production is currently circa 1 - 2 % of the total European production (circa EUR 100 million). The market demand and the additional costs for larger tile manufacturers to adjust their mass production to the technology make the entrance of new SME tile companies specifically to this market very interesting.
The results to date have indicated that a contact and direct UPV measurement system is feasible and enables on-line density measurement of green tiles. The out-of-press system could be sold also for monitoring the density in other stages of the ceramic producing cycle (for example after firing or drying) increasing again the number of products potentially sellable.
Finally, the off the press off the line system can be seen as a lab test equipment alternative to mercury intrusion and/or the penetrometer.
Project website: http://www.ceramgroup.com/projects/novapress/index.html