1. Introduction
In the field of modern manufacturing, casting is a crucial process for producing various components. The pump body, as an important part in many industrial systems, requires high – quality casting methods to ensure its performance and reliability. Traditional sand – casting techniques often face challenges such as complex mold – making processes, long production cycles, and limited precision. With the development of advanced manufacturing technologies, 3D printing technology has emerged as a promising solution, especially in sand – casting applications. This paper focuses on the in – depth research of applying sand mold 3D printing technology to pump body casting, aiming to explore its advantages, key processes, and the overall impact on the casting industry.
2. Pump Body Structure and Its Significance in Casting
2.1 Pump Body Structure Analysis
The pump body is a complex component with an irregular shape. As shown in Figure 1 (here, a self – drawn figure of the pump body’s 3D model can be inserted, similar to the one described in the original Chinese paper but in English annotation), the pump body in this study has dimensions of 410 mm×503 mm×170.5 mm and a net weight of 57 kg. It belongs to the shell – type casting category and is made of HT200 material. Its non – symmetric structure poses challenges in the casting process, as different parts have different thicknesses and cooling requirements.
| Parameter | Value |
|---|---|
| Dimensions | 410 mm×503 mm×170.5 mm |
| Net Weight | 57 kg |
| Material | HT200 |
| Structure Type | Shell – type, non – symmetric |
2.2 Influence of Pump Body Structure on Casting
The non – symmetric structure and varying wall thickness of the pump body affect the filling and solidification processes during casting. Thinner walls cool faster than thicker ones, which may lead to uneven solidification and potential defects such as shrinkage porosity and cracks. Therefore, understanding the pump body structure is the first step in formulating an appropriate casting process.
3. Sand Mold 3D Printing Technology: Principles and Advantages
3.1 Principles of Sand Mold 3D Printing
Sand mold 3D printing is a rapid prototyping technology. First, the casting’s gating system, upper and lower molds, and sand cores are designed using 3D modeling software. Then, the designed models in STL format are imported into Magics software for slicing. After slicing, the model is transferred to a 3D printer for printing. During printing, a binder is selectively deposited onto the sand layer by layer to form the desired mold structure. Figure 2 (a self – drawn figure showing the 3D printing process of the sand mold, with English – labeled steps) illustrates the basic process flow.
3.2 Advantages over Traditional Sand – Casting Methods
Compared with traditional sand – casting, sand mold 3D printing technology has several significant advantages. It eliminates the need for making master patterns, which reduces production costs. The ability to create complex – shaped sand molds and cores allows for greater design freedom. In addition, the high precision of 3D – printed sand molds leads to higher – quality castings. The following table summarizes the comparison between the two methods:
| Comparison Items | Traditional Sand – Casting | Sand Mold 3D Printing |
|---|---|---|
| Master Pattern Making | Required, time – consuming and costly | Not required |
| Complex Shape Molding | Difficult, limited by mold – making techniques | Easy, can create any shape |
| Precision | Relatively low | High |
| Production Cycle | Long | Short |
| Cost for Small – batch Production | High | Low |
4. Casting Process Design for Pump Body
4.1 Selection of the Parting Surface
The selection of the parting surface is a critical step in casting design. For sand mold 3D printing, the parting surface should first ensure successful mold assembly. In most cases, it is chosen at the maximum cross – sectional area of the casting. For the pump body, as shown in Figure 3 (a self – drawn figure indicating the parting surface of the pump body, with English – labeled explanations), the parting surface is selected at its largest cross – section. This choice is based on several factors: minimizing the number of sand molds to reduce assembly errors and difficulty, and considering the complexity of the internal and surface structures of the casting.
4.2 Design of the Gating System Scheme
Three gating system schemes, namely top – pouring, side – pouring, and bottom – pouring, were designed for the pump body casting, as shown in Figure 4 (a self – drawn figure with three gating system schemes for the pump body, clearly labeled in English). Each scheme has its own characteristics in terms of filling and solidification processes.
| Gating System Scheme | Filling Characteristics | Solidification Characteristics |
|---|---|---|
| Top – Pouring | Molten metal fills from the top, fast filling at the beginning | Solidification from top to bottom, outer wall cools first |
| Side – Pouring | Molten metal enters from the side, relatively uniform filling | Solidification from top to bottom, uneven solidification trend |
| Bottom – Pouring | Molten metal fills from the bottom, slow filling at the beginning | Solidification from top to bottom, areas near the gating system cool slower |
5. Numerical Simulation Analysis of Casting Processes
5.1 Simulation Software and Mesh Generation
AnyCasting software was used to simulate the casting processes of the three gating system schemes. The pump body was meshed into 1 million regular cube grids with an average size of 5.6 mm×5.6 mm×5.6 mm, as shown in Figure 5 (a self – drawn figure of the meshed pump body model, with English – labeled mesh details). The casting process parameters, including casting method, material, sand mold material, pouring temperature, and pouring time, are set as follows:
| Casting Parameters | Value |
|---|---|
| Casting Method | Sand Casting |
| Material | HT200 |
| Sand Mold Material | Furan Resin Sand |
| Pouring Temperature | 1450 ℃ |
| Pouring Time | 18 s |
5.2 Simulation Results and Defect Analysis
5.2.1 Top – Pouring Scheme
The simulation results of the top – pouring scheme show that the overall solidification sequence is from top to bottom and from outside to inside. As shown in Figure 6 (a self – drawn figure showing the solidification process and defect prediction of the top – pouring scheme, with English – labeled data and areas), the outer wall of the pump body cools first due to its thinness, and the internal part cools last. Through the analysis of combined defect parameters and probability defect parameters, it is predicted that defects may occur on the outer wall and in the riser.
5.2.2 Side – Pouring Scheme
For the side – pouring scheme, the solidification sequence is also from top to bottom and from outside to inside, but the solidification trend is uneven. As shown in Figure 7 (a self – drawn figure showing the solidification process and defect prediction of the side – pouring scheme, with English – labeled data and areas), after solidification, shrinkage porosity defects mainly occur in the riser, and few defects are found on the casting itself, which has little impact on the quality of the casting.
5.2.3 Bottom – Pouring Scheme
The bottom – pouring scheme shows that the areas near the gating system cool slower. As shown in Figure 8 (a self – drawn figure showing the solidification process and defect prediction of the bottom – pouring scheme, with English – labeled data and areas), defects are likely to occur at the junction of the riser and the casting near the gating system, as well as in the middle hole wall and plane areas. This is because the bottom runner has poor heat dissipation and slow melt flow velocity.
Based on the simulation results, the side – pouring gating system is selected as the optimal scheme due to its fewer defects in the casting body.
6. Practical Verification of the Casting Process
6.1 Sand Mold and Core Preparation by 3D Printing
Due to the complex structure of the pump body, 3D printing technology was used to make the sand cores. The designed sand core cone – shaped structure can enhance the fixing strength and facilitate placement. The sand mold was divided into two parts. In the 3D printing process, the AFS – J1600 printer was used, and the layer thickness was set to 0.4 mm, and the scanning line width was 1.5 mm. Figure 9 (a self – drawn figure showing the 3D – printed sand mold and core, with English – labeled parts) shows the 3D – printed sand mold and core.
6.2 Casting and Post – processing
After printing, the unbonded and solidified dry sand in the sand mold was cleaned using a vacuum cleaner and a dust – blowing gun. Before pouring, zircon powder was sprayed on the pouring surface of the sand mold to improve the surface quality of the casting and reduce gas evolution. The casting was poured with HT200 material at a temperature of 1450 ℃ for 18 s. After cooling, the outer sand mold was removed, and the casting was obtained. After removing the riser and gating system, the final pump body casting is shown in Figure 10 (a self – drawn figure of the final pump body casting, with English – labeled inspection points). Inspection results show that the casting is of high quality, with no obvious shrinkage porosity or surface defects.
7. Conclusion
This research on the application of sand mold 3D printing technology in pump body casting has achieved the following results:
- Through the numerical simulation analysis of AnyCasting software for top – pouring, side – pouring, and bottom – pouring schemes, the side – pouring gating system was determined to be the best choice, which effectively shortens the trial – mold cycle.
- The use of 3D printing technology to make sand molds significantly reduces the sand – mold making time.
- The combination of numerical simulation technology and sand mold 3D printing technology can greatly shorten the development and trial – production cycle of new casting products, improve production efficiency, and reduce production costs. This research provides a reference for the application of advanced manufacturing technologies in the casting industry and promotes the development of the casting process towards a more efficient and precise direction.
In the future, with the continuous development of 3D printing technology and numerical simulation algorithms, it is expected that more complex and high – quality castings can be produced with higher efficiency and lower costs. Further research can focus on optimizing the printing materials and parameters, as well as improving the accuracy of numerical simulation to better guide the actual casting production.
