Visual Guide to Ram Pressing Water Filter Pots

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By Rosy Heywood, Research Associate at the Centre for Print Research, UWE Bristol

The ceramics research team on the Healthy Waters project have designed and 3D printed a press mould to create porous water filter pots. The moulds were then fitted into a piston extruder to create a ram press. The ceramic ram-press function is an adaption of our hydraulic clay extruder, which is also used as a delivering system for ceramic paste in our experiments with large-scale 3D printing with robotic arms in other research projects.  

The benefits of ram pressing the pots is we could produce consistently sized and quality pots at speed. The clay used was a clay and sawdust mix and we have found it to be difficult to work with as it has a loose and fragile consistency. However, we have found ram pressing the clay forces the mixture to bind together due to the pressurised conditions. The pots are then fired at a low firing temperature of 800 degrees. The sawdust burns off in the kiln and the result is a porous ceramic structure. This research has been inspired by the methodology of Potters for Peace in their report titled ‘Best Practice Recommendations for Local Manufacturing of Ceramic Pot Filters for Household Water Treatment’.

Figure 1 Ram press set-up
Figure 2 Pot after pressing

The sample pots were manufactured in four different clay types in order to test the water filtration efficacy of a range of clays. The clays used were; red earthenware, white earthenware, porcelain and white stoneware. Each clay was used in powder form and mixed with equal parts of sawdust in volume before being combined with water to make plastic clay. The clay was then worked and wedged in preparation for ram pressing.

The video below shows our process of building a filter pot using the ram press. 

Ram press process for creating water filter pots for direct water filtration. Research conducted at the Centre for Print Research, UWE Bristol

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