Utilizing Powder Bed Fusion Additive Manufacturing Technology to Fabricate Parts with Controlled Porosity and Permeability Characteristics for Filtration Applications

Abstract Whilst the main focus of metal Additive Manufacturing (AM) aka metal 3D printing has been to produce fully dense parts; the main aim of this research is to use the technology to fabricate metallic permeable parts with controlled porosity characteristics so that they may be used as a high performance, high-pressure and cleanable and therefore “green” reusable filters for various industrial applications. The fusion bed technology, more specifically Direct Metal Printing (DMP) has been utilized to fabricate test parts with porous structure that was later tested for filtration efficiency. In DMP process, the part is built in thin layers with each layer a cross-sectional slice of the shape. This method makes it possible to design and manufacture intricate parts with detailed internal sections that is not always possible with conventional manufacturing methods. The technique also makes it possible to design and manufacture combination of solid and porous sections in one operation or in another word a complete filter assembly to be used straight off the print with no or minimal post processing required. Another advantage of using DMP is the possibility of seamlessly incorporating features like pleats to increase the filtration area, incorporate additional strengthening structures and support structures if required as well as manufacturing a graded media with larger pores on the outside getting finer as you approach the centre. The printing parameters have been selected to achieve optimum combination of tightly controlled pore size range, size distribution and mechanical strength to promote the optimum filtration efficiency and dirt-holding capacity; at the same time maintaining the structural integrity for operation under high pressures, a wide range of flow conditions, operating temperature, and compatibility with a wide range of process fluids. The results from the first round of tests on scaled down samples demonstrated that the fabricated porous metal parts are suitable to be used in a wide range of applications and operating conditions. They are bi-directional in terms of flow and as a result, they are cleanable and reusable. They can be designed to a variety of shapes and sizes with ease and are recyclable if needed. This approach of manufacturing cleanable filters can reduce the demand for new and newly processed materials. In addition, it can reduce production, distribution, and storage costs. Hence less energy usage, less pollution, and less demand for hazardous waste disposal and associated challenges with disposal and the impact on the environment.