1.
C. Bleicher
Fraunhofer Institute for Structural Durability and System Reliability LBF, Germany
EVALUATING THE CYCLIC MATERIAL BEHAVIOUR OF MATERIAL IMPERFECTIONS IN THICK-WALLED NODULAR CAST IRON WITH THE HELP OF NON-DESTRUCTIVE TESTING

2.
K. Asano
Kindai University, Japan
MICROSTRUCTURE AND PROPERTIES OF CAST METAL MATRIX COMPOSITES

3.
Badarinath Kalkunte1, Lorenzo Valente2, Cristian Viscardi2, Vlastimil Kolda3
1Calcom ESI SA, Switzerland
2Ecotre Valente SRL, Italy
3Mecas ESI SRO, Czech Republic
VIRTUAL DIMENSIONAL CONTROL TO PREDICT AND MEASURE THE FINAL SHAPE OF THE CASTING PART

4.
M. Petrič1, R. Cerc Korošec2, M. Vončina1, P. Mrvar1, S. Kastelic1
1Faculty of Natural Sciences and Engineering, University of Ljubljana, Ljubljana, Slovenia
2Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubjana, Slovenia
APPLICATIONS OF 3D PRINTED POLYMER PATTERNS IN CASTING TECHNOLOGIES

1.
C. Bleicher
Fraunhofer Institute for Structural Durability and System Reliability LBF, Germany

EVALUATING THE CYCLIC MATERIAL BEHAVIOUR OF MATERIAL IMPERFECTIONS IN THICK-WALLED NODULAR CAST IRON WITH THE HELP OF NON-DESTRUCTIVE TESTING

Abstract

Material imperfections in large castings made of nodular cast iron as shrinkages and Dross are not easy to detect with non-destructive testing (NDT) methods. In this context, the question arises if and to which amount the quasi-static and cyclic fatigue strength of the component is reduced, if such imperfections are present. Since present standards and guidelines do not offer a possibility for a doubtless component’s lifetime assessment, detected imperfections cause a significant amount of work in foundries to remove those local imperfections or to reject the complete component. The latter case occurs, if a secure assessment of the component’s lifetime cannot be performed.
The aim is thus to find appropriate NDT methods to determine the characteristics of material imperfections, such as its stiffness and density, in thick-walled nodular cast iron and to set up a concept for the lifetime assessment of components affected by shrinkages and Dross based on information coming from NDT.
During two research projects, large cast blocks made from different nodular cast iron, were cast with large areas of Dross and shrinkages. These blocks were investigated with different NDT methods, such as ultrasonic Sampling Phased Array and mechanised ultrasonic testing, to obtain digitalised information on the position and the characteristics of the specific imperfection. Investigations with magnetic particle inspection, computer tomography and sulphur tests also took place. Afterwards, fatigue and tensile specimens were removed from the cast blocks and tested under strain and stress control to determine the cyclic strain-based material behaviour of the different specimens with and without imperfections. Special attention was paid to the assessment of the material stiffness or the virtual Young’s modulus, which is significantly influenced by the imperfection in each specimen.
During the investigations, it could be shown that it is possible to determine specific parameters of the imperfections such a stiffness and density, which can digitally be transferred to numerical analysis and which can furthermore be used for a fatigue assessment of an affected component.

Key words: nodular cast iron, thick-walled, material imperfections, non-destructive testing

2.
K. Asano
Kindai University, Japan

MICROSTRUCTURE AND PROPERTIES OF CAST METAL MATRIX COMPOSITES

Abstract

Microstructure and properties of the metal matrix composites, mainly the short carbon fibre- reinforced aluminium composites fabricated by squeeze casting, were focused on. For the PAN- based carbon fibre-reinforced pure aluminium matrix composite, the reaction product (Al4C3) was formed at the fibre/matrix interface. When the Al-Si alloy was used for the matrix and/or the pitch-based carbon fibre was used for the reinforcement, the reaction product was not observed. Thermal conductivity of the Al-Si alloy increased due to the pitch-based fibre reinforcement, while that decreased due to the PAN-based fibre reinforcement. Compressive strength of the PAN-based fibre composite was greater than that of the pitch-based fibre composite. Wear loss of the Al-Si alloy under dry sliding wear was drastically decreased due to the carbon fibres. Under severe wear condition such as high sliding speed and high applied load, the wear loss of the pitch-based fibre composite was less than that of the PAN-based fibre composite.

Key words: composite, aluminium, carbon fibre, squeeze casting

3.
Badarinath Kalkunte1, Lorenzo Valente2, Cristian Viscardi2, Vlastimil Kolda3
1Calcom ESI SA, Switzerland
2Ecotre Valente SRL, Italy
3Mecas ESI SRO, Czech Republic

VIRTUAL DIMENSIONAL CONTROL TO PREDICT AND MEASURE THE FINAL SHAPE OF THE CASTING PART

Abstract

The automotive industry is brutally competitive and increasingly requires high performance castings with high structural integrity, good mechanical properties and intolerance dimensional control to go further into the sub-assemblies and assembly.
Casting components are subjected to continuous and varying thermo-mechanical loading during the entire manufacturing process; casting process and also in cases where heat treatment need to be applied. These result in evolving stresses through the process. They accumulate especially while the casting is inside the die during filling & solidification, and are released and re-distributed during die opening, part ejection, and subsequent post operations like trimming and heat treatment. These result in continuous dimensional variation during the manufacturing process. It is thus important to study these variations through the process and be able to overcome in case of a mismatch in the final cast geometry as opposed to the desired dimensions prescribed by the part owner.
Process modelling has continuously evolved, and though residual stress modelling has always been talked about in the past, there has always been challenges to predict and compare the dimensional variations between simulation and reality. The entire modelling process itself to map the die temperatures as closely as possible and master every aspect of the process in the simulation have always been studied more deeper and deeper.
All these lead to the possibility to have a virtual dimensional control to predict first the final part geometry from simulation and compare it with the actual cast part or the target part dimensions. This is exactly a manner in which the part dimensional quality assurance is done on shop floor in the recent years, comparing 3D scan of the as-cast part with the target part dimensions.
Such kind of integrated tools during the development stage allows the die designers to take necessary action early on and allows radically shortening of the metrological activities in the QA department. This is another effort to bridge the gap between design, manufacturing and QA.

Key words: Casting simulation, die castings, HPDC, thermal stresses, die lubrification, dimensional control

APPLICATIONS OF 3D PRINTED POLYMER PATTERNS IN CASTING TECHNOLOGIES

Abstract

This paper describes a research of different 3D printing materials and printed models used for different casting technologies. In the research the Fused Deposition Modelling (FDM) and Stereolithography (SLA) 3D printing techniques were used with different printing materials such as Polylactic Acid based material (PLA), Poly Vinyl Alcohol based material (PVA) and Acrylate Photopolymer resin (Castable). Printed models were characterised by dilatometric analysis, Differential Scanning Calorimetry (DSC) and by ash content determination in order to evaluate the possibilities of such produced models being used at investment casting technology. The analysed properties such as thermal expansion, melting point of polymer material and ash content after burnout process are crucial at achieving good quality of cast parts.
Results showed that the melting points of PVA and PLA materials are at 140 to 180 °C which is suitable for the burnout process. Thermal expansion is the most suitable for PVA and PLA materials since they are not expanding during the heating of the samples. The Castable resin has the highest melting point and is expanding until 120 °C which makes it less interesting for investment casting models production. The ash content was the highest at PLA material and the lowest at PVA an Castable resin. According to presented results the PVA material is the most suitable for use in investment casting technology.

Keywords: 3D-printing, polymeric materials, investment casting