## 7 Challenges and Future Prospects in Design for Additive Manufacturing of Lattice Structures
### Challenges Related to Design for Additive Manufacturing of Lattice Structures  
Given the complexity of the geometry, designing intricate lattice parts can be challenging. This could result in manufacturing difficulties related to the support structure requirements, printability, and post-processing constraints. AM often results in rough surfaces that require post-processing in order to improve the surface design and mechanical properties. Post-processing methods for lattice parts tend to be challenging to optimise [1; 2; 6; 7; 8; 13; 14; 17]. For instance, challenges associated with removing support structures without damaging delicate lattice features. After printing, lattice parts typically call for post-processing to remove support structures. The delicate nature of lattice features makes this process challenging, as excessive force or the use of improper techniques could damage the structure. Addressing these post-processing limitations may require careful study and manual labour. Furthermore, identifying and developing materials that are equally good for AM and with the capacity to attain the required mechanical properties of lattice designs is presently a significant challenge as well [13], for example, developing polymers or metal alloys that perform well during the layer-by-layer deposition process in 3D printing. Some materials might not be naturally compatible with specific additive manufacturing procedures. Certain polymers or metal alloys, for example, can present challenges during the printing process due to their melting viscosity, cooling rates, or adhesion, compromising the overall quality and structural integrity of lattice structures. The current methods for optimising lattice structures are not capable of taking advantage of AM's capacity. These methods fail to take full advantage of multiple objectives, as well as other aspects, such as support structure requirements, layer adhesion, and minimising the manufacturing time while maximising the structural performance. Adapting designs for different scales and resolutions in AM technologies, as well as guaranteeing the structure's integrity and performance over different sizes, is presently challenging [5; 56; 11; 16; 38; 47; 55]. In a lattice design, weight reduction is balanced with the mechanical strength and thermal conductivity. Traditional optimisation methods could zero in on a particular objective, such as minimising the material usage in lightweight structures. However, in additive manufacturing, where complex lattice geometries are feasible, it is possible to optimise multiple targets at the same time, such as obtaining lightweight designs with precise mechanical and thermal properties.  
Maintaining consistency and quality control in AM is difficult, particularly for lattice parts requiring a specific degree of porosity inherent in the structure and geometrical accuracy [11; 16; 38; 55]. In addition, building advanced multi-material and multi-color printing technologies in order to attain adaptable and useful lattice structures is also difficult. To ensure that the planned lattice parts meet performance and safety requirements that could vary from typical solid structures, advanced validation procedures are required. These methods are presently challenged when it comes to predicting the behaviour of resulting lattice designs accurately [11; 16; 17], for instance, constructing lattice parts with a specific degree of porosity for use in bone implants. Particular lattice parts, such as those used in medical implants, could require an accurate degree of porosity for biological integration. Maintaining consistency in attaining the correct porosity over multiple prints while adhering to quality control is often difficult due to differences in material characteristics, printing conditions, and post-processing steps.