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Content archived on 2024-05-29

Develop methods of manufacturing customized flexible membranes using laser technology

Final Report Summary - LASER-MEM (Develop methods of manufacturing customized flexible membranes using laser technology)

Flexible membranes are used in many industries to remove solids such as activated sludge from fluids. However, the state-of-the-art methods used for manufacture of polymer membranes have some inherent key disadvantages. The characteristics of state-of-the-art membranes are mainly achieved through outgassing processes in a polymer material. These processes can be hardly controlled. The techniques used result in material that has a fixed structure and it is not possible to introduce flexibility by changing its characteristics or modifying the material to meet the individual needs of any application.

The applications of these membranes are, therefore, limited and do not enable the material to be exploited to its full potential. Where they are used system designers are not able to optimize their designs, and have to modify their specifications to use the material in the form in which it is available.

The LASER-MEM technology used a different method of manufacture to overcome all the disadvantages inherent in existing products. An innovative laser process allowed manufacturing polymer membranes with individual and application specific characteristics. This new technique enabled the characteristics of the membranes to be controlled and provided the capability to manufacture sheets to suit the requirements of individual applications.

The work of LASER-MEM project had been organised in a number of work packages which had the following objectives:
- Characterisation of bi-directional molecular orientation in thick sheet, characterisation of hole size, shape and density referring to specific flow rate, back flush and clogging, characterization of laser drilling onto oriented polymerics at process temperature, design of membrane.
- To develop laser machining techniques and combine with scanning and focusing features to produce accurate and predictable conical holes and to control and minimise re-cast.
- Using the techniques established in previous objectives, develop a test platform to enable the various sample filtration and aeration membranes to be produced. The laser and associated optics will be developed to produce the optimum hole profiles and pitch to produce membranes suitable for aeration purposes. A handling system will be designed to allow the sample material to be accurately positioned and manoeuvred to create sample membranes. Resulting membranes will be assessed for structural integrity and geometric accuracy.
- Development of membrane system design, integration of laser and platform equipment, manufacture of prototype membranes, characterise process parameters versus membrane geometry properties.
- Build filtration test rig, validation of membrane performance (turbidity filtrations, flow rate, rupture strength, life testing), techno-economic and market validation.

The development of the LASER-MEM project had provided the following results:
- laser drilling system, including membrane handling platform, control unit, etc.;
- new experience in laser optics design and manufacture;
- a lot of new experiences about the laser ablating process;
- experience in membrane design; -
good results concerning filtration and aeration application.

On the other hand, some points were still needed for the process to be commercially exploitable:
- long-term experience under field conditions;
- adjustment to different applications and capacities;
- reduction of laser manufacturing time;
- operating cost reduction;
- more commercial product orientation.

These latter aspects were outside the focus of the project since the aim of the Cooperative Research (CRAFT) programme is the development of pre-competitive prototypes and processes.