# Micro-Gear Point Cloud Segmentation Based on Multi-Scale Point Transformer
## 2 A Dataset for Micro Metal Gears Based on MIM
### Manufacturing of Micro Metal Gears through MIM  
Metal Injection Molding (MIM) is an emerging powder metallurgy technology particularly well-suited for high-volume production of precision micro-sized components. The specific process flow diagram for this technique is depicted in Figure 1.  
The Metal Injection Molding (MIM) process primarily consists of four key stages: mixing and granulating, molding, debinding, and sintering. In these stages, mixing and granulating is the first and a relatively independent step, which includes several sub-steps such as premixing of powder, preparation of binder, mixing of powder and binder, and finally the granulation process. The produced granules, referred to as feedstock, are used in the second stage of molding; during this molding stage, the feedstock is heated to a specific temperature to melt it, then injected under pressure into a prepared mold. The mold should have temperature controls to facilitate demolding and cooling, after which the parts cool down and are demolded. After this step, the parts are called green parts, at which point they already possess the complex structures required by the parts. The third part, the debinding stage, is a unique step in the MIM process, where, due to the large amount of binder in the formed green parts, about 30% to 50% of the binder needs to be removed from the blank, which directly relates to the feedstock composition. After this step, the parts become extremely fragile; however, as the parts contain metal powder, they do not shrink or collapse. The final stage, sintering, is crucial for the densification of the parts and differs from traditional powder metallurgy sintering. In traditional powder metallurgy, pressed parts already possess a relatively high density and only about 10% of porosity needs to be eliminated for densification. However, after the debinding process in MIM, up to about 40% porosity remains, leading to significant shrinkage during sintering. Due to the significant changes in the shape of components throughout the MIM process, this study will collect point cloud data of the components at each stage of the MIM process to illustrate these unique transformations. The experimental subject of the dataset is a spur gear with 17 teeth and a module of 0.5 mm, as illustrated in Figure 2. The specific parameters are outlined in Table 2.  
Figure 1: MIM process flowchart. Figure 2: Geometric model of micro-gears. To fully reflect the characteristics of the MIM process, this study has designed and implemented an orthogonal experiment. There are four core process parameters in MIM: mold temperature, nozzle temperature, injection pressure, and holding time, which can affect the three-dimensional shape of the gears. The experimental scheme designed for this study is outlined in Table 3. The production experiments are conducted using the equipment shown in Figure 3. \begin{table}
\begin{tabular}{c c} \hline
**Parameter Name** & **Parameter Value** \\ \hline Normal Module (mm/mm) & 0.5 \\ Number of Teeth (z) & 17 \\ Pressure Angle (\(\alpha\)/\({}^{\circ}\)) & 20 \\ Addendum Coefficient (0) & 0.06 \\ Pitch Circle Diameter (D/mm) & 8.5 \\ Root Circle Diameter (Df/mm)) & 7.21 \\ Tip Circle Diameter (Da/mm)) & 9.56 \\ Tooth Pitch (pt/mm)) & 1.571 \\ \hline \end{tabular}
\end{table} 
Table 2: Gear size parameter information. Figure 3: Babyplast6/10 Micro Injection Molding machine (The Rambaldi Group, Bologna, Italy). \begin{table}
\begin{tabular}{c c c c c} \hline
**Group** & **Mold Temperature** & **Nozzle Temperature** & **Injection Pressure** & **Holding Pressure** \\  & (°C) & (°C) & (Bar) & **Time (s)** \\ \hline  
\\ \hline \end{tabular}
\end{table} 
Table 3: Experimental plan. Moreover, to further diversify the morphological characteristics of gears, various materials have been selected for gear manufacturing, including but not limited to popular materials such as 316L and 17-4 ph.