Application of sand mold casting modelling for casting pump volute

This work details the development of a gating system for sand mold casting utilizing advanced computer technologies in the casting industry. The study employs advanced methods to manufacture a component referred to as the pump volute. Made from the EN-GJN-HV600(XCr23) alloy, this component displays superior technological characteristics, notably for the production of sand mold gravity castings. SolidWorks software is utilized to generate 3D models of the component and the fill system based on predetermined dimensions. Subsequently, the component is imported into Pro-CAST software to conduct a simulation. Various time parameters were inputted during the study. Post-simulation, defects were scrutinized, and the casting system underwent modification to eliminate them. The process was iterated on the software and its efficacy was verified to be faultless.


Introduction
The sand-casting process is one of the traditional methods employed for manufacturing castings with modest dimensional accuracy.Sand casting stands out as the oldest casting method in history.Sand casting still accounts for the largest share of production in the field of foundry castings.The enduring popularity of sand casting is attributed to its cost-effectiveness and its ability to produce castings from a variety of materials, ranging from a few grams to several tons in weight.In sand casting, molten metal is poured into molds made from a specialized sand mixture, typically composed of 90% silica, along with binding agents, such as clay, which bind the particles together [1].
The demand for casting components with desired properties and controlled solidification is on the rise, as numerous cast products like automotive, industrial and structural components tend to fail in challenging conditions due to less-than-optimal material characteristics.
In modern times, numerical modeling of the solidification process has gained significant importance.Finite element method (FEM) is successfully employed in the mathematical simulation of the moldfilling process in traditional casting.To achieve defect-free products, specific guidelines must be followed, starting from model preparation and concluding with the metal pouring stage [2].The formation of defects during the casting process depends on various factors such as pouring temperature, mold characteristics, filling rate, and so on.Neglecting these factors leads to a high degree of product defects [3].Recent advancements in technology allow for the identification of defects and their causes using 3D modeling software.To achieve the best possible combination of initial factors, we have developed an analytical experiment by modeling the casting process with a set of varying parameters.
Producing pump volute castings devoid of defects is a crucial task in the industry.Optimal manufacturing process design, encompassing the gating system, is instrumental in delivering seamless castings utilizing modeling techniques on Pro-CAST software.P. Prabhakar Rao illustrates the modeling tool's application in designing a sand-casted crusher casting in their publication [4].Research in the casting industry has shown that the Pro-CAST modeling tool is highly reliable, proving to be an effective method for achieving accurate results.
Pro-CAST is a three-dimensional software package designed for modeling solidification and fluid flow processes.It is intended for numerical simulation of the flow of molten metal and solidification phenomena in various casting processes, including sand casting.Research [4] has shown that casting simulation has proven to be highly effective in identifying defect locations and addressing them, providing a visual representation of the mold filling, solidification, and cooling processes.Adjustments made to the dimensions and geometry of the gating system successfully eliminated defects such as shrinkage porosity in the cast component.After importing the 3D model into Pro-CAST, researchers monitored key parameters, including solidification time, shrinkage porosity, and percentage of solidification.
The pump volute, as shown in figure 1, is a part of a pump casing used for fluid transport.pump volutes are employed in various types of pumps, including those for water, fuel, oil, chemicals, as well as in the food and pharmaceutical industries.They are effective in handling viscous and dense fluids, as well as materials with a high content of solid particles.Typically manufactured via casting, the pump volute is built from wear-resistant white cast iron.
Computer modelling techniques have become popular in the casting process with the advancement of science and technology.Numerical simulation models the pump volute casting process and facilitates the analysis and visualization of liquid metal dynamics.The process provides practical production recommendations that are highly valuable.Pro-CAST software can predict the impact of varied pour temperature on casting quality [5].It locates and measures porosity shrinkage and monitors the liquid metal flow during the casting process.Causes can be analyzed to guide production, providing a scientific basis to optimize the casting process and improve casting quality.

Numerical modeling procedure
The objective of this project is to simulate the solidification mechanism of the pump volute and analyze the results to provide some aspects of logical reasoning for the selection of components and optimize casting parameters to achieve improved properties of the cast parts.The component was created using SolidWorks software for modeling and CAE software: Visual-CAST (solver -Pro-CAST).
The casting material is a highly alloyed cast iron EN-GJN-HV600(XCr23), used for manufacturing cast components of mining and metallurgical equipment with dimensions up to 2500x2500x300 mm and weighing up to 3000 kg.The chemical composition of EN-GJN-HV600(XCr23) is provided in table 1. figure 2  IOP Publishing doi:10.1088/1742-6596/2697/1/0120373 system, created using SolidWorks software.The overall dimensions of the pump volute casting are 928 mm x 795 mm x 470 mm, with minimal variation in thickness.The thinnest section measures 30 mm, while the thickest is 35 mm, and the structure is complex.
The required casting quality is assessed in accordance with standard inspection procedures.The placement of the casting inside the mold and the selection of the parting plane during casting are determined based on the geometric and structural characteristics of the component.This selection is crucial to ensure proper mold filling, prevent defects, and facilitate the efficient extraction of the component from the mold.The use of casting modeling and analysis software aids in optimizing the placement of the casting and parting planes, thereby enhancing the and efficiency of the manufacturing process.
There are a number of parameters to consider when designing a gating system, including shrinkage porosity, the presence of gas bubbles, the potential for cracking and burn-in.These aspects have a significant impact on the quality and reliability of the castings and therefore require careful analysis and optimization as part of the design process.
Another important aspect is to reduce turbulence by keeping the flow velocity in the gates at 10-12 kg/s.Once the gate trajectories have been determined, calculations must be carried out to determine the dimensions of the gate system elements using standard methods.The results of the calculations are given in table 2. Only with the correct sizing values is it possible to ensure an efficient gating system and defect-free casting.

Technical specifications
In order to make the modelling more realistic, the following input values have been introduced into the software.
In the Mesh-CAST module, a total of 2517790 casting cells have been set at a size of 10 mm.Additionally, the sand-casting mode and relevant parameters have been chosen based on table 3 in the Pro-CAST module.To ensure appropriate heat transfer, air cooling has been set for the surface of the mold and riser.
In this study, the choice of materials for the preparation of casting mold involves the use of the following components: 90% silica sand, 3% liquid glass, 3% bentonite and 3% moisture.To optimize the casting process and to compensate for shrinkage during the solidification of the casting, exothermic inserts were used in the gating system.These inserts consisted of the following components: vermiculite, liquid glass, and kaolin.These measures made it possible to reduce heat losses during the casting process and ensure more efficient molding of the casting, which helps to improve the quality of the initial product.The heat transfer coefficient between the core and the casting.500 (W/(m 2 •K) [6] 10 The heat transfer coefficient between the cooler and the casting.4000 (W/(m 2 •K) [6]

Results and discussion
Sand casting is a metal casting technique that offers several advantages over other approaches.The use of a sand mold allows for the casting of various types of metals, as well as the creation of complex geometric shapes and components.Additionally, this method of casting is less expensive than alternative approaches due to the low cost and availability of sand and clay materials.
The pouring system is meticulously crafted to align with the product and functions as a pathway for the molten metal to stream into the mold cavity, compensating for any shrinkage during solidification of the casting.A well-executed pouring system design is extremely crucial in promoting short feed paths and swift metal flow, which deters untimely solidification and guarantees top-notch castings.In thermal regions of the casting that solidify at a slower rate, measures such as direct contact with the gating system or installation of risers need to be taken to avert the formation of shrinkage defects that arise during solidification.
A conventional two-turn gating system was implemented in these trials.Multiple gate system designs and mold filling arrangements were employed to effectively eradicate overfill defects.

Test gating system I
A conventional casting system was developed for cast iron castings in the initial test due to restrictions in the casting design, which precluded the use of alternative metal feeding methods.Subsequent data analysis revealed shrinkage covering the entirety of the product due to a defect in the solidification process, visible in figure 4 (b).The macroporosity exhibited in the solidification depicted in figure 4 (b) implies considerable shrinkage inside the component, verifying the ineffectiveness of the gating system in use.Consequently, adjustments were implemented to the metal feed system to eliminate the necessity of designing a new system for succeeding tests.

Modelling Test II
This is the second gating system model displayed in figure 2 (b) for subsequent simulation tests.At first, the feasibility of this model was uncertain.Nevertheless, after examining the overall dimensions of the component, it was concluded that it was viable given the existing facilities.As part of the gating system's development, several changes were implemented.These include increasing the system's size, introducing sprue-feeding profits, using exothermic inserts and a cooler, as demonstrated in figure 2 (b).The objective of these changes was to move porosity outside the component and produce quality castings, as shown in figure 3 (b).The aforementioned feeding system was later converted into a STEP file, which was then imported into the Pro-CAST software for simulation purposes.After entering all of the input values, the simulation was rerun.The metal-filled component appeared as demonstrated in figure 3

Analyzing Test II
The same type of analysis was carried out as in the previous case.The detected defects are shown in figure 4 (a).The temperature contour and fluid flow were analyzed.Interpretation of the results of the analyses of the different methods led to the following conclusion.After solidification, the results of test II were compared with the results of test I.With the first type of gating system, defects were found throughout the entire volume of the casting (figure 4 (b)).In the second gating Thus, these defects did not affect the casting.Therefore, the second casting system was chosen to produce the casting in the production area.table 2 shows the casting system calculation steps to calculate the casting system coefficients.The values of pouring system ratio can be seen above 1:1.2:15.In this way, defect free production of castings can be ensured.The pump volute was designed and engineered according to the dimensions given in the 2D drawings.The gating system was designed considering various factors such as flow rate, heat transfer, pouring time and furthermore it was designed with gating ratio more than 1:1.2:1.5 at liquid velocity of 10-12 kg/s as per the requirements given in tables 2 and 3.
Tracking was carried out by entering the appropriate values into the Pro-CAST software and running the simulation.The simulation analyzed fluid flow, temperature, contours and hot spots to ensure that the casting was free of defects.Since defects were found throughout the casting in Test I, this type of gating system was modified with a different design to eliminate them.In Test II, a new gating system was developed for defect-free casting.The gating system was modified by increasing the size of the gating system, introducing sprue-feeding profits, using exothermic inserts and a cooler.
The new model in Test II was modelled and analyzed.The analysis showed that increasing the size of the gating system and the introduction of sprue-feeding profits can compensate for shrinkage during solidification of the casting.The use of exothermic inserts and a cooler provide directional crystallization during solidification and guarantees a defect-free casting.After solidification of the casting, there were defects only in the gating system and profit, which can be seen in figure 4 (a).Software modelling in gating system design speeds up the process, increases design variability, reduces cost and improves product quality.Process visualization identifies defects and hot spots, ultimately reducing scrap and improving yield.

Conclusions
The casting process was modelled using Pro-CAST software by assigning parameters such as pouring temperature, flow rate, pouring time, heat transfer coefficient, proper materials (mold and metal), and radiation.The simulation result found that the gating system was modelled considering various parameters such as flow length, presence of air, foreign material entrapment, velocity in the gate and gating ratio.The result at each stage was interpreted using different methods such as gate entry velocity method, solid phase fraction method, shrinkage porosity method and all necessary modifications are made accordingly.The modified pouring system was modelled, analyzed for defects and by simulation it was confirmed that there was no defect.From the experimental results, it was seen that the new casting system will help to ensure stable production of quality castings using SolidWorks and Pro-CAST programs.

Figure 1 .
Figure 1.Three-dimensional model of the pump volute.
(a) displays the three-dimensional model of the pump volute casting along with the gating APITECH-V-2023 Journal of Physics: Conference Series 2697 (2024) 012037

Figure 2 :Figure 3 .
Three-dimensional model of the pump volute casting together with the gating system.a b Pattern of mold filling and temperature fluctuations of the gating system at different stages.

а b Figure 4 .
Comparison of defects between test II (a) and test I (b).

Table 2 .
Gating system parameters

Table 3 .
Parameters of the numerical modelling process