The Amorph and REMOVE projects were undertaken as part of the flagship TWI Core Research Programme (CRP) which is designed to meet the needs of TWI Industrial Member companies. Projects are selected that address the most significant challenges currently faced by TWI and its Industrial Members, in relation to specific technology areas and/or industry sectors that have been identified as being of critical interest to future operations.
AMorph: 4D printing for field morphing structures
4D printing refers to the fabrication of three-dimensional structures with the added dimension of ‘time’, pertaining to the ability of structures to change shape post-printing, or in the ‘field’, if exposed to predefined environmental stimuli. This dynamic behaviour is activated by an external energy input such as temperature, light, pH or voltage. In addition to the endless shape possibilities that 3D/4D printing can offer, it also provides for a broad spectrum of sizes.
The Amorph project focused on very small devices, or micro-robotics, typically based on materials that have less complex, more straightforward and mostly monolithic designs. 4D printing at small scale holds very high potential for micro-robotics, introducing a new level of versatility and complexity into the forms and configurations produced; and allowing for simpler use and integration of a wide variety of smart materials. This renders the design of micro-robots with more sophisticated geometries and advanced capabilities, a fast and cost-effective process. Therefore, Amorph explored the availability of smart materials in raw form that could be suitable for use in additive manufacturing (AM) processes, investigated the properties of the printed smart materials for different process parameters and settings, manufactured and characterised prototype micro actuators and investigated the control methodologies for 4D printed actuators.
On completion, the work undertaken on the project served to advance the field of 4D printing technology and is most relevant to the aerospace sector, however, it also shows promise for application in other sectors such as consumer goods and healthcare.
REMOVE: Effortless, support structure removal for metal 3D printing
Laser Powder Bed Fusion (LPBF) for metals is one of the most commonly used and rapidly developing additive manufacturing (AM) technologies, capable of producing complex, thin and lightweight components, in contrast to traditional manufacturing which limits those characteristics. However, it faces difficulties related to the construction of overhang structures, and the warping deformation caused by thermal stresses, because 3D printing fabricates parts in a layer-by-layer manner. In LPBF, support structures are always required, thus producing overhangs without support structures results in collapsed parts, while adding unnecessary supports increases the material and post-processing required.
The TWI CRP project REMOVE built on existing expertise in LPBF-based AM, software development, design for AM and data-driven optimisation to develop a web-based, decision support platform for the optimisation of support structures, towards ease of removal and zero-defect, laser-based parts. The platform gives the user an indication of the ease of removal when designing support structures, while maintaining the support volume and limiting the risk of warpage to a minimum.
Benefits to industry include: drastically decreasing the time needed to remove support structures, resulting in more rapid uptake of LPBF as a production method; reducing the number of parts damaged during post-processing; increasing the probability of successfully printing zero defect parts; lowering CO2 emissions via the optimisation of support volume and placement, resulting in just the right amount of support material; and realising a web application to facilitate independent decision workflows for support design and generation, introducing to industry an innovative tool for effortless, reliable and sustainable AM.