assessment of the model whether it satisfies all the basic rules.
Two common errors that occur during processing were topological error and normal vector error. Whenever a solid model shares a common vertex, a non‐manifold error would occur that results in topological errors. In such cases, a single solid model was split into two individual models so that the model fixing and repairing would be easier. The latter type of error occurs when the model fails to follow the orientation rule. As a result, the vertices are not closed sufficiently causing normal vector errors. The repair mechanism involves the reordering of the vertex indices in an ordered pattern of triangular facets (Chao et al. 2011). Other common errors encountered during image processing are cracks, holes, voids or missing/ duplicate facets, and flipped orientations (Liu et al. 2009). All these errors fixing and repairing mechanisms are simplified and become easier with modelling software such as Fusion 360, Autodesk ReCap, Trinkle, Sculpteo, MakePrintable, MeshLab, etc. which are specially designed for repairing the STL files (Table 1.4). These software saves time and helps to improve the printing quality.
Figure 1.8 Common STL errors.
1.9 Food Printing Platforms
The food printing platform consists of a well‐coordinated XYZ axis system, a dispensing system, and a microprocessor control unit connecting the computer with the printer. The emergence of food printing not only leads to industrial level printing but also makes the possibility of using 3D printers at domestic kitchens. Thus, food 3D printers would become a common kitchen appliance that allows the users to define their own recipes by either downloading the digital recipe files from an online source or creating a new user‐defined digital recipe. Food 3D printing will be a technological cutting edge that helps the users to manipulate the number of ingredients as well as to monitor the calorie intake. Food printing recipes follow two different platforms namely universal, and user‐defined platforms.
1.9.1 Universal Platform
Universal platforms are the existing open‐source printing systems adapted for food applications from allied sectors such as polymer printing. The use of this type of available printing platform for food applications shortens the processing time and saves energy (Sun et al. 2015a). Most of the food printing systems available in the literature were based on universal platforms. Researchers had used these platforms for the printing of food matrices like protein pastes and cake dough and studied the effect of hydrocolloids in textural modification of different food systems (Lipton et al. 2010). A desktop 3D printer, MakerBot was adapted for food printing by modifying the existing extruder head to be suitable for food printing (Millen 2012). Although universal platforms save time and cost, these platforms were not suitable for printing a wide range of food materials since food is a complex matrix comprising of varied physical and chemical composition.
1.9.2 User‐Defined Platform
These are the self‐developed 3D printing platforms created for overcoming the limitations existing with the universal platforms. Based on the specific requirements of printing and the nature of food matrices, self‐developed platforms are defined by users (Hao et al. 2010). These platforms allow the users to have a proportional degree of freedom that helps in achieving flexibility in design components and working mechanisms. Further, these platforms allow for modification and up‐gradation of printing systems. Researchers have developed an in‐house‐built customized extrusion‐based 3D printer CARK (controlled AM robotic kit) specially designed for food applications (Anukiruthika et al. 2020). Here, the components of the printer were selected based on specific requirements for food printing. The developed delta‐based food printer was applicable for printing a wide range of food materials such as food pastes, hydrogels, colloids, etc.
Table 1.4 Software used for repairing STL file after 3D scanning.
| Web page | Features | Operating system | Access |
|---|---|---|---|
| Autodesk Meshmixer | Helps in mesh repairing that is featured with functions such as sculpting, scaling, building, mirroring, and cutting | Windows, OS X and Linux | Free |
| MeshFix | Open‐source STL repair software that fixes various defects such as holes and self‐intersections resulting in a water‐tight triangular mesh output | Windows | Free |
| MeshLab | Featured with tools for editing, managing, inspecting, texturing and converting 3D meshes | Windows, Linux, iOS, Mac OS X and Android | Free |
| MakePrintable | Assess 3D design model and provides print statisticsHelps in configuring the model characteristics and yields algorithm for 3D printing | Online browser | Both free and paid |
| Autodesk Netfabb | Offers tools for repairing meshes, adjusting thickness, merging, and deleting parts thereby proving powerful functioning | Windows | Paid |
| 3D Builder | Enables model visualization, provide editing capabilities, and helps in 3D editing and validating | Windows | Free |
| Blender | Open‐source 3D repairing software that supports modelling, animation, simulation, and motion tracking | Windows, OS X and Linux | Free |
| FreeCAD | Open‐source parametric 3D software used primarily to design and repairAllows users to easily modify design and changing its parameters | Windows, OS X and Linux | Free |
| Emendo | Allows users to automatically identify number, type and location of STL errors | Windows and OS X | Paid |
| Open3mod | General‐purpose 3D model viewerEfficient tools to inspect, filtering and isolating errors | Windows | Free |
| Sculpteo | Allows user to upload, repair, analyse and optimize the STL files | Online browser | Free |
| 3D Tools | Allows users to assess STL files based on dimensional parameters like volume and surface area prior to mesh repair | Online browser | Free |
1.9.3 Applicability of User Interface Systems
To widen the applications and usage of 3D food printers, researchers are now focussing on developing a simplified