Determination of Acceptable Quality Limit for Casting of A356 Aluminium Alloy: Supplier’s Quality Index (SQI)

Erzi Erzi,Colak Colak,Gürsoy Gürsoy,Dispinar Dispinar,Yüksel Yüksel

doi:10.3390/met9090957

Abstract

Aluminium and its alloys have been widely used in the automotive industry for some time and A356 is one of the most popular aluminium alloys today in the sector. It contains approximately 7 wt.% Si and 0.3 wt.% Mg. Due to the defects that may be present in the cast parts, expected mechanical properties may not be reached and this alloy may perform in service under its potential. In a low pressure die casting, several precautions have to be taken in order to produce high quality and defect-free castings. Temperature of casting and the schemical composition of the melt is recorded continuously. Die temperature, pressure levels and their durations are optimized; degassing and fluxing operations are performed. Yet, regardless of the precautions, there could still be rejected parts. It is becoming clear that a good quality raw material is one of the most underrated points of the industry and that the starting material has a great effect on the final product and it should be taken in to account more seriously. Therefore, regarding the first rule of Campbell’s 10 Rules of Casting, in this study, the quality of the starting material of supply chains for a wheel manufacturer was investigated. Chemical compositions were compared, fluidity tests, mechanical tests and bifilm indexes of these various sources and ingots were measured and a final quality index was proposed to create a reference for the quantification of quality of supplier’s ingots. This new index was compared with the rejection rates.

Highlights

Low pressure die casting (LPDC) is one of the most popular choices of cast in aluminium part production methods, in highly critical applications
Fluidity tests, mechanical tests and bifilm indexes of these various sources and ingots were measured and a final quality index was proposed to create a reference for the quantification of quality of supplier’s ingots
The change in geometry, the cross-section area during filling will result in uncontrolled flow of the melt and occurrence of turbulence will lead to porosity formation

Summary

Introduction

Low pressure die casting (LPDC) is one of the most popular choices of cast in aluminium part production methods, in highly critical applications. This is mainly due to the complete control of filling, lowered runner design and feeders, and high production rates. There usually exists an acceptable range of porosity in cast parts which determines whether they pass the quality control or not. Bifilms were removed from the melt and fatigue life of cast parts were increased. In this work, four different ingot supplier’s quality was assessed and the correlation between melt quality and the rejection rate of cast parts were evaluated

Experimental

Fluidity

Discussion

Change

Optical microscopy images of of