Bernhard J. Stauder¹, Hubert Kerber², Peter Schumacher³, ¹Nemak Linz GmbH; A-4030 Linz, ²Austrian Foundry Research Institute - ÖGI; A-8700 Leoben, ³Montanuniversität Leoben, Chair of Casting Research; A-8700 Leoben
FOUNDRY SAND CORE PROPERTY ASSESSMENT BY 3-POINT BENDING TEST EVALUATION

Franck Gigez, Fondarex SA, St-Légier, Switzerland
INNOVATIONS IN VACUUM DIE CASTING

Jožef Medved¹, Primož Mrvar¹, Janko Čevka², Maja Vončina¹, Dominik Jagodic¹, ¹University of Ljubljana, Faculty of Natural Sciences and Engineering, Aškerčeva 12, 1000 Ljubljana, ²Exoterm d.d., Struževo 66, 4000 Kranj
DETERMINATION OF THERMAL PROPERTIES OF EXOTHERMIC-INSULATING MATERIALS

Klančnik¹, M. Drobne¹, I. Kogovšek¹, J. Mastnak¹, P. Fajfar², P. Mrvar², J. Medved², ¹Valji, d.o.o., Železarska cesta 3, Slovenia, ²University of Ljubljana, Faculty of Natural Sciences and Engineering, Aškerčeva 12, Slovenia
HIGH AND LOW ALLOYED INDEFINITE CHILL CAST IRON: IMPACT ON MECHANICAL AND MICROSTRUCTURAL PROPERTIES

FOUNDRY SAND CORE PROPERTY ASSESSMENT BY 3-POINT BENDING TEST EVALUATION

Abstract

Improved understanding of foundry sand core properties is a key requirement for high precision casting process development. The present work demonstrates the potential to evaluate mechanical and functional sand core properties using precisely acquired 3-point bending test load curve data applying standard bending test geometries.

Four organic binder systems have been investigated. Further to bending strength and the elastic modulus, which can be directly derived from the load curves, a load curve pre-treatment to eliminate sample settlement effects was applied for a correct deflection and stiffness analysis. The consumed mechanical work shows characteristic elastic and plastic work portions until fracture, which are specific for different sand cores, respectively their condition. Dimensionless indicators to quantify core brittleness have been developed based on curve and on work parameters.

In general for mechanical evaluations of resin bonded sand cores, visco-plastic effects need to be considered, as for not fully hardened binder systems decreased strength, deflection and work of fracture were observed at lower load speeds.

The benchmark results show that the load curve evaluation concept is a suitable tool to analyse foundry sand core properties more sensitively.

Franck Gigez, Fondarex SA, St-Légier, Switzerland

INNOVATIONS IN VACUUM DIE CASTING

Abstract

In the past 20 years the thin-walled body structural parts in the automotive industry have been developed significantly. Meanwhile, the vacuum die casting process has been upgraded and adapted to the latest requirements.

A large variety of structural parts, such as shock towers, door frames, hatchbacks, dashboards, crossbeams and pillars have a direct impact on car weight thus fuel consumption and CO2 emissions. These new designs and lightweight components have to be heat treatable, weld-capable and ductile. Today, the world-leading foundries are using the high-end vacuum technology for their challenging automotive productions of structural parts.

Each foundry has its own approach and philosophy. Thus, Fondarex is committed to find the best overall setup for each die caster. We take care of defining the optimal layout for the best vacuum characteristics, in combination with the most suitable vacuum system having the required process control. Furthermore, the technical support and training are essential for the proper integration of a vacuum system.

Fondarex proposes different sizes of steel Chill-Blocks with aerodynamic profiles, as well as a complete range of Supervac vacuum valves. Those valves are closed by the kinetic energy of the metal with the best evacuation capacity, which guarantees the lowest vacuum level in shortest time.

With the new Highvac series, a wide range of vacuum systems are proposed to the die caster. Innovative control possibilities, such as vacuum measurement in the cavity, vacuum regulation, pollution and profile control, leak test, evacuated air volume measurement and evacuated air humidity control, are integrated in the process. The transfer of the vacuum production data can be made by Ethernet, Profinet and Profibus while the vacuum curves through analog signal, Profinet and Profibus.

As the casting requirements keep getting more stringent, so do the necessary production control capabilities. By listening to the needs of our clientele and to the industry’s requirements, Fondarex has developed a sensor capable of accurately determine the humidity content from the air evacuated out of the cavity. Equipped with the patents, Fondarex is ready to unveil its newest partner for the Highvac Premium 2C and the Highvac Ultimate 4C series; already proven companions in successful high-integrity castings. Fast, reliable and accurate, it measures and processes analytical data per vacuum channel and per shot.

Die castings of structural parts develop continuously. It is our challenge and honor to lead the industry by regularly innovating the vacuum technology for new applications and projects.

DETERMINATION OF THERMAL PROPERTIES OF EXOTHERMIC-INSULATING MATERIALS

Abstract

Exothermic-insulating materials are used as auxiliary materials in steel foundries, cast iron foundries, non-ferrous foundries and elsewhere. Materials with exothermic and/or insulating function differ in composition, exothermic effect, insulating ability, ignition temperature, method of manufacture and other properties. For effective use of such materials, the manufacturer should be familiar with thermal properties and experimental techniques to achieve the appropriate characteristics at the manufacturing process.

To control an exothermic-insulating material no special investigation techniques are prescribed, which allow the determination of thermal properties, so there is no standardized system for their determination. For the industrial control, the device for investigated materials was developed and designed. Using the differential thermal analysis (DTA) the thermal properties of raw materials and manufactured exothermic-insulating materials were investigated, with an aim to optimize and calibrate the industrial device in Exoterm-IT d.o.o.

HIGH AND LOW ALLOYED INDEFINITE CHILL CAST IRON: IMPACT ON MECHANICAL AND MICROSTRUCTURAL PROPERTIES

Abstract

As newer and improved materials are being constantly developed, indefinite chill cast iron (ICDP) remains one of the most suitable and cost efficient alloys used in cast rolls for last finishing stands of standard HSM, blooming or Steckel mills. Improvements of the ICDP alloy can be made by adding special carbide builders (SCB) such as vanadium, niobium, titanium and tungsten. The impact of these additions on microstructural development and mechanical properties of the ICDP working layer (wear resistance, dynamic strength and thermal fatigue resistance) has been studied. Research shows that by adding a higher amount (> 1 %, mass. fraction) of SCB wear resistance, dynamic strength at low cycles and thermal fatigue resistance in terms of reducing the number and density of cracks improved. Meanwhile tensile strength does not seem to change significantly. On the other hand, high SCB addition can inhibit graphite formation as well as cause severely long thermal cracks which can lead to problems during roll exploitation. As rolls are tailored to meet specific mill conditions, a decision on the amount of SCB added must be made. Results of the presented study can help choose the appropriate amount in regards to the mill’s demands.

In the study, we have shown that via suitable return sand reclamation, inert substance and fine fraction levels can be maintained and the sand consumption reduced. Silica sand consumption was decreased by just under 40%, and also resulted in the reduced consumption of bentonite clay and blacking. The reclamation investment should return within less than 2 years.