Through the Die: An Exploration into Clay Extrusion
Through the Die: An Exploration into Clay Extrusion
A booklet documenting work carried out under the AHRC Leadership Fellow Award: ‘Smart Tooling for Ceramic Profile Extrusion: New Approaches to Industrially Focused Interdisciplinary Practice Based Research’.
This booklet covers research into new approaches to clay extrusion technology. The booklet illustrates the exploration with pictures of the research journey including toolmaking, testing and experiments with creative applications of the knowledge.
Front cover: Photogram of extrusion die profile.
1. Test of extruded clay pipe.
2. Empirical test of extrusion die.
3. Hydraulics for extrusion machine.
4. Empirical extrusion tests.
All photos: F Menger 2021
Ceramics items
have been produced for millennia and the medium is an integral part of our culture – past and present.
Project Background: Material, History and Use of Process
Ceramics can be broadly defined as the results of clay that has been hardened by heat–typically through a high temperature firing process. Ceramics items have been produced for millennia and the medium is an integral part of our culture – past and present. The medium is valued for its unique functional qualities in terms of durability, longevity and aesthetic qualities. The ceramics is used extensively for domestic artifacts including plates, cups, and decorative pieces, but the medium is also one of the most ubiquitous material in our build environment in shape of bricks, cladding, roofing tiles and many other architectural components.
Among the core shaping method that are used in the production of ceramics is extrusion. The core concept of extrusion is simple; the method is based on principle of forcing plastic clay through a profile, commonly known as a ‘die’, the result is a continuous linear clay section which can then be cut into pieces to produce individual parts. The extrusion process dates back to the 17th century primarily developed as way to make the production of bricks and other architectural components more efficiently1. The process continues to be used extensively in the architectural ceramic sector with almost all mass-produced ceramic bricks being made in this way.
1. Industrial extrusion die.
2. Ridge tile extrusion at Wienerberger’s Sandtoft plant. All photos: T Jorgensen 2019
Extrusion is also use in the production of some very specialised ceramic parts, including filters for catalytic converters. Equally, hand operated clay extruders are also frequently part of the equipment pool in craft pottery setups and typically used to create handles and other smaller parts in support of other production methods such as throwing, pressing and casting. However, in many other areas of ceramics production including industrially produced tableware and sanitary pieces, the use of the extrusion process as the core shaping technology remains very limited. The cause for this underutilisation is unclear and contrasts the significant advantages the extrusion process presents, in particular the process has the potential to produce pieces very quickly and unlike other ceramic forming techniques, such as casting and pressing, clay extrusion requires no moulds. This background provides part of the rationale for this research – to further explore the underutilised innovation potential of the clay extrusion process.
3.
4. Extrusion at Wienerberger’s Sandtoft plant.
5. Extrusion dies at Tommerup Ceramic Work Center, Denmark. All photos: T Jorgensen 2019
Heavily worn industrial extrusion die.
The advance of new digital fabrication technologies, such as 3D printing and computer-controlled machining, has revolutionised many sectors and industries.
New Technologies, Research Questions, Jugstrusions
and Interdisciplinary Approaches
The advance of new digital fabrication technologies, such as 3D printing and computer-controlled machining, has revolutionised many sectors and industries. However, in ceramics the impact of these new technologies has so far been relatively minor – mostly limited to specialised technical ceramics or used by a relatively small number of individual creative practitioners.
Equally, the core approaches with clay extrusion have seen little innovation in decades, and digital fabrication has so far had little impact on the way this process is used. The main aim of this project is to address this through a research question defined as: how can digital technologies and robotics extend the current uses of clay extrusion into more innovative and design-led applications?
A number of objectives was defined to address this main aim. Included in these objectives was an ambition to explore how knowledge from different disciplines can be combined to deliver innovation in a particular area. Some of the first ideas for the project came from creative experiment with the clay extrusions, which resulted in a series of extruded jugs (titled ‘Jugstrusions’). Knowledge from such creative explorations can lead to insights that are valuable in entirely different applications and sectors. Throughout the project we sought to cross-fertilise the investigation with a wide range of perspectives and approaches, ranging from theoretical modelling, industrial production know-how and artistic experimentation.
1. 3D printing of extrusion die.
2. Jugstrusion, detail.
3. Jugstrusion dies.
4. Extrusion of Jugstrusion
All photos: T Jorgensen 2019
Toolmaking in this project was undertaken both in the digital and physical realm.
Toolmaking: New Industrial Revolution, Innovation,
3D Printing and Machine Building
The notion of toolmaking is one of the most central aspect of the project, and critical to the aim of delivering innovation with the clay extrusion process. During the initial industrial revolution in 18th century, the development in toolmaking capabilities was one of the main reasons for the boom in innovation in this period2. The emergence of digital fabrication tools in recent years has frequently been described as a new industrial revolution. In this project we explored how new technologies can again boost the innovation process in new toolmaking scenarios.
Toolmaking in this project was undertaken both in the digital and physical realm. In the digital realm, toolmaking was carried out through the creation of software scripts that automated the design of the extrusion dies. This was done in ‘Grasshopper’ – a visual programming environment in the design software Rhino 3D3. Using Grasshopper we created automated software scripts capable of generating three-dimensional design files for extrusion dies from simple numeric inputs. The digital files from this process can be sent to a 3D printer to fabricate the die. The tool making workflow in this set-up is fast, extremely versatile and cheap, it means that new designs for extrusion dies can developed easily and design iterations can be carried out in rapid cycles.
1. Rhino Grasshopper, visual scripting for extrusion die.
Photo: T Jorgensen 2020
But toolmaking in this project goes much beyond the creation of software scrips. We created and built tools for almost all stages of the clay extrusion workflow, including constructing the actual extrusion machine itself. For this we used a mixture of standard components, in particular the Unistrut4 system and combined such of-the-shelf parts with bespoke components fabricated by a local company via computer-controlled laser cutting.
As a power unit we used a standard hydraulic system, which is incredibly powerful – easily capable of generating the levels pressures used in industrial clay extrusion situation. The system enables us to test the strength of the 3D printed extrusion dies. The dies are fabricated in 3D printed polymers, typically using biodegradable Polylactic Acid (PLA) plastic. The strength of the 3D printing parts would often surprise us, with some dies withstanding pressures up to 100 bars. However, certain dies geometries may be less resilient and break during testing. However, the semi-automated workflow that has been established means that alterations can easily be carried out. Another approach that has been developed to address the issue dies breakages, is a method of incorporating stainless steel elements with the 3D printed parts in a hybrid construction approach.
Throughout the project we have made many other supporting tools, jigs and components. Most frequently using a combination of manual and digital fabrication tools. We typically use cheap, consumer level, 3D printers to fabricate bespoke parts. The use of equipment that is affordable and widely available is one of the objectives of the research, seeking to develop innovation approaches that are open to all.5
2. Extrustrusion dies and other tools. Photo: F Menger 2021
3. 3D printed extrusion dies. Photo: T Jorgensen 2020
4. 3D printing of extrusion die. Photo: T Jorgensen 2021
We have made many other supporting tools, jigs and components.
1. Setting up the extrusion machine.
Photo: T Jorgensen 2020
2. Constructing the hydraulic extrusion machine.
Photo: T Jorgensen 2020
3. Unistrut brackets. Photo: F Menger 2021
Research Methods and Approaches:
Experimental Tests, Empirical Observations, Robotic Arms, Rich Media and Theoretical Modelling
The methods used in this research is overwhelmingly based on practical experiments. Sometimes these tests would be carried out as open-ended explorations with the outcome highly unpredictable, with an approach largely driven by curiosity: what happens when we do this? Other experiments are much more structured, for example, the process of trying to pin-point particular issues or aspects of the process, a research approach that is known as empirical testing.
One of the biggest challenges in producing ceramic pieces via extrusion is how the pieces behave during drying and firing when the clay shrinks around 10-15%. Tensions from the extrusion process also mean that the pieces can bend and crack during the drying and firing stages – even though the extrusions were perfectly straight during production. To record this material behaviour, we have developed an approach of extruding test pieces out on paper and then carefully trace around the pieces with coloured pens at the various key stages to identify distortions and other issues in the production workflow of the pieces.
1. Extrusion tests.
2. Test extrusion being analysed. All photos: F Menger 2021
All the practical tests in the project, both experimental and empirical, are recorded in bespoke database templates on an iPad. These templates allow documentation to be recoded in a number of rich media formats, such as numerical data, images, movies or audio recordings of observations and researcher reflections.
The nature of the clay extrusion makes theoretical calculations of the outcome very challenging – although some work has been done to develop algorithms that can help to predict the flow of clay in an extrusion situation. As a part of this project, explorations of such theoretical modelling have also been carried out to see if such methods can help to direct particular design approaches with the dies. With this aspect, collaboration with Dr Damien Leech – a theoretical physicist, has enabled calculations to be developed which can predict how particular geometries in the dies might affect what pressures are needed to extrude clay through the dies.
3. Empirical test recorded via paper tracing. Photo: F Menger 2021
4. Logging test results on databases. Photo: F Menger 2021
5. Fired clay extrusion clay tests stored with paper tracing roll. Photo: F Menger 2021
6. Research explorations. Photo: T Jorgensen 2021
The research has resulted in a number of insights, with the potential for new creative and commercial opportunities.
Utilising Research Knowledge:
Creative Explorations
The research has resulted in a number of insights, with the potential for new creative and commercial opportunities. One of our creative partners is CFPR researcher, Lisa Sheppy, who is undertaking a PhD study into the tissueprinting process for ceramic decoration. Lisa has used the extrusion process to generate shapes to carry her tissueprint experiments. She used particular dies that generate extrusions which curve and twist. By manipulating the clay as it emerges from the die, she has generated many unique shapes to test the tissue-print graphics.
Other work that explores the creative use of the knowledge generated from the research is a collaboration with artist Sarah Fraser. Fraser works with communities to record individuals’ journeys within the domestic or public space. These journeys are expressed as lines, which can be used as a basis to produce physical forms via clay extrusion.
1.
Extrusions for ‘Copper Sounds’.
2. Extrusion of coping stones shapes. All photos: T Jorgensen 2021
This work is aligned with Sarah’s interests in ceramic coping stones. Sarah’s artistic vision is to visualize individual journey lines as an integral part of the local urban environment through the production of extruded ceramic coping stones.
The production system developed in this research is ideal for realising these coping stones and the wide range of profiles generated from Sarah’s work is, in turn, also a perfect way to test the capabilities of the new clay extrusion approaches.
The researchers own creative background is also utilised for testing the outcomes of the research. For example, extruded ceramic pipes are now being explored for their use in music performance through Sonny Lightfoot’s band; Copper Sounds.
3. Lisa Sheppy shaping extrusions.
4. 3D printed extrusion dies for coping stone shapes. All photos: T Jorgensen 2021
Utilising Research Knowledge:
Industry uses and novel applications
The application of the research knowledge in industrial contexts is a key objective of the project and many of the test are carried out in relation to this particular objective. The aim is to expand the current use of clay extrusion with new capabilities and solutions.
A novel concept of integrating function into the dies that enable coatings to be applying on both the inside and outside of the extruded shapes is an example of one of the finding of the project that has particular relevance in industrial commercial contexts. Architect Rosa Urbano-Gutierrez from University of Liverpool has provided input into the project with her particular research interest in terms of exploring the sustainability benefits of the ceramic medium in new architectural applications. As a way of testing new approaches with the extrusion die construction, Rosa’s designs for ceramic louvres were used as case study for the industrial relevance of the research.
1. Extrusion die with clay slip coating capability.
Photo: T Jorgensen 2021
2. Extrusion test with internal slip coating.
Photo: F Menger 2021
3. 3D printed die parts for ceramic louvre shape.
Photo: T Jorgensen 2021
The creation of tooling workflows that enable rapid testing of novel die designs is also generating possibilities for the use of ceramic extrusion in entirely new contexts. Based on the results of this project new applications in high performance applications are now being explored. In relation to these possibilities we are working with the National Composite Centre (NCC), which is the UK’s leading centre for advanced industrial applications for composites. The NCC are particularly interesting in the potential for extruding ceramic matrix composite (CMC), where ceramic paste is mixed with in organic binders for projects in sectors like aerospace, nuclear and construction.
Experiments are also under way to use of Robotic Arms to bend the clay extrusion to accurate radii as they emerge from the die. This would enable the production of one-off ceramic parts in entirely new applications and contexts.
4. Extruded ceramic louvres.
5. Robotic arm with gripper and hydraulic extrusion machine. All photos: F Menger 2021
The aim is to expand the current use of clay extrusion with new capabilities and solutions.
Profiles: Researchers, Centre, Funder and Research Partners
Dr Tavs Jorgensen Principal Investigator tavs.jorgensen@uwe.ac.uk
Tavs Jorgensen is Associate Professor at the Centre For Print Research. Tavs has a background as a craft potter and designer for the ceramic industry before developing a career in academia. Tavs taught for more than 10 years at the Royal College of Art and has guest lectured at many leading international institutions including MIT, Royal Danish Academy and School of the Art Institute of Chicago. Tavs’ research interests are focused on exploring the design and innovation potential presented by new digital fabrication technologies –particular with the glass and ceramics mediums.
Centre For Print Research (CFPR) https://cfpr.uwe.ac.uk
This research project is carried out at the Centre For Print Research (CFPR) – one of the UK’s leading research centres. The work of CFPR is internationally recognised and the centre has won numerous research grants, most recently a 7.7million pound Expanding Excellence (E3) award from Research England.
Opposite: Hydraulic extrusion machine. Back cover: Photogram of extrusion die profile (negative). All photos: F Menger 2021
Sonny Lee Lightfoot Research Associate sonny.lightfoot@uwe.ac.uk
Sonny has worked as Research Associate and Research Technician at CFPR since 2019, with specialisms in digital fabrication and ceramics. Sonny graduated from the Fine Art Course at UWE in 2013 and has previously worked as a Technical Demonstrator in 3D Digital Design and Ceramics, as well as Visiting Lecturer at Bath Spa University. He also has a collaborative art practice, Copper Sounds, which is a multidisciplinary expedition into sound, ceramics, printmaking, mould making and digital craft.
Funder and Research Partners
The project is funded through an Arts and Humanities Research Council (AHRC) Leadership Fellow Award formally titled ‘Smart Tooling for Ceramic Profile Extrusion: New Approaches to Industrially Focused Interdisciplinary Practice Based Research’. The project is being undertaken with collaborative input from sector leading industry partners including Sibelco, Arup, Wienerberger and Centre for Window and Cladding Technology (CWCT).
Graphic Design
J Graphic & Digital Design j-graphicdesign.co.uk
Text Tavs Jorgensen
Photography
Frank Manger and Tavs Jorgensen
Print
Taylor Brothers, Bristol taylorbros.uk.com
Many thanks to Wuon-Gean Ho and Andy Johnson and everyone in CFPR involved with the project.
Centre For Print Research
University of the West of England
Faculty of Arts, Creative Industries & Education
W Block, Frenchay Campus, Coldharbour Lane Bristol BS16 1QY UK
