Computer aided engineering (CAE) simulation for the design optimization of gate system on high pressure die casting (HPDC) process

Hyuk-JaeKwonaHong-KyuKwonb
aDepartment of Civil Engineering, Cheongju University, Cheongju-city, Choongnam, South Korea
bDepartment of Industrial & Management Engineering, Namseoul University, Cheonan-city, Choongnam, South Korea

Abstract

A most important progress in civilization was the introduction of mass production. HPDC molds are one of main technologies for mass production. Due to the high velocity of the liquid metal, aluminum die-casting is so complex where flow momentum is critical matter in the mold filling process. Actually in complex parts, it is almost impossible to calculate the exact mold filling performance with using experimental knowledge. Due to this condition in the design procedure, the simulation is becoming more important. Simulation can make a casting system optimal and also elevate the casting quality with less experiment. The most advantage of using simulation programs is the time and cost saving of the casting layout design. The condition selection of HPDC mainly relied on the experience and expertise of an individual worker in casting industries. Systematic knowledge accumulation of die casting process was an essential matter to get optimal process conditions.

In present casting industries, product development paradigm is shifting from traditional trial-and-error to proof-of-concept based on CAE -enabled simulation. Due to the high velocity of the dynamic behavior of the casting system in working conditions, aluminum die casting is a very complex process in which flow momentum is a critical issue in the mold filling process. In the new production development paradigm, CAE simulation plays an important role because it models the entire casting process and reveals the dynamic behavior of the casting system. In this research, CAE simulation was performed by using the simulation software (AnyCasting) in order to optimize the gate and runner design of an automobile part (Oil Pan_BR2E) which is well known and complicated to achieve a good casting layout. Filling analysis was used to find out the size and location of the gate and proper runner system design. By the modification of the gate and runner system and the configuration of overflows, internal porosities caused by air entrapments were predicted and reduced remarkably. With the solidification analysis, internal porosities caused by the solidification shrinkage were also predicted.

Introduction

The method of HPDC is one of the most important techniques for manufacturing automobile parts and electronic parts, and one of the economical casting techniques that can manufacture complex shapes at one time. When manufacturing HPDC mold, generally, the casting layout design should be considered based on the relation among injection system, casting condition, gate system, and cooling system. In current casting industries, the design and development of a casting layout is a trial-and-error method based on heuristic know-how. The solution achieved in such a way lacks scientific calculation and analysis [1], [2].

CAE simulation technology helps practitioners generate, verify, validate and optimize the design solutions. In an aspect of product quality and defect prediction perspective, CAE simulation is a most technologically efficient and cost effective technology for analysis and evaluation of casting product quality and defects [3], [4].

In this research, CAE was performed by using the simulation software (AnyCasting) in order to optimize casting design of an automobile part (Oil Pan on Fig. 1). Generally, oil pan is assembled on the below of the crank case and its purpose is to collect oil after a lubrication action conducted by oil pumper. The simulation results were analyzed and compared carefully in order to apply them into the production die-casting mold. During the filling process, air entrapments cause internal porosities that produce the defects of casting parts. They are usually occurred due to the non-uniform and vortex flow while filling the melt into the cavity of the mold. The flow junction zones (air entrapments) were predicted and reduced remarkably by the modification and the configuration of the gate system. The solidification shrinkage is usually occurred on the thick sections of a casting part and also causes other porosity defects of a casting part. Internal porosities caused by the solidification shrinkage were predicted with the solidification analysis.

Section snippets

General die casting process

Die casting is a process in which the molten metal fills into the mold with the high pressure. The inverse of the part's shape basically consists of the cavity and core of the mold. Various casting production processes require the diverse physical property of the base material. The following six steps are the basic die casting process [3].

Step 1: The mold is open in the initial situation and ready for starting a new cycle.

Step 2: The mold is closed by moving the clamping system.

Step 3: The

CAE simulation of die casting process

The commercial package (AnyCasting) was used to optimize a casting design before fabricating production HPDC mold. The software had been developed by AnyCasting Co., LTD. and employed a hybrid method mixing a PM (Porous Media) Method and a Cut-Cell Method that complements a drawback of the conventional FDM (finite difference method) rectangular mesh. The mold filling and solidification analysis are to be improved more accurate, and also calculation speed is improved more than 50% by decreasing

Results and discussion

By comparing the simulation results in the points of the filling process and solidification, the casting design with case 3 produces much better results. But there are some improvements existed on case 3 according to the simulation results. As shown on Fig. 10(A), an isolated area is expected on the middle of the part while filling up the melted material into the cavity of the mold. In order to prevent the porosity defects on those areas and make the better melt flow, direction of ingate (G3)

Conclusions

In current casting industries, the design and development of a casting product and process are a trial-and-error process based on heuristic know-how [9], [10]. The solution achieved in such a way lacks scientific calculation and analysis. Using CAE simulation with AnyCasting, the following results had been achieved:•

According to the filling process, the final casting layout on Fig. 10(B) is better than other casting layouts on Fig. 3 because of the location of the flow junction zone, and the

Acknowledgment

Funding for this paper was provided by Namseoul University.

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