Development of an Experimental Setup to Investigate Influences on Component Distortion in Gravity Die Casting and a First Variation of Temperature Control Strategy

Nino Wolff,Uwe Vroomen,Tobias Hohlweck,Andreas Bührig-Polaczek,Christian Hopmann

doi:10.3390/met11122028

Abstract

Distortion (1), residual stresses and hot cracks can facilitate significant decreases in quality characteristics of casting products. Their reduction by a suitable component design (2) and process control is therefore desirable. In the casting process, these characteristics are assumed as a result of the combination of solidification shrinkage paired with the local self-feeding and the geometric constraints imposed on the component by the mold. In gravity die casting (3) of aluminum (4) with thermally well conducting and rigid metal molds, the control of solidification through a localized adjustment of the heat balance (5) appears to be a suitable approach to minimize these effects. The development of an experimental setup for the assessment of the interdependencies of the alloy, casting geometry and cooling are described in this work. A first series of experiments with A356 aluminum alloy and the introduction to the different methods of evaluation are presented. Furthermore, an approach to improve the understanding of the underlying mechanisms is outlined.

Highlights

Distortion, residual stresses, and hot cracks are decisive quality characteristics of cast parts and, depending on their characteristics, facilitate the need for additional finishing steps and rejects
Distortion (1), residual stresses and hot cracks can facilitate significant decreases in quality characteristics of casting products. Their reduction by a suitable component design (2) and process control is desirable. These characteristics are assumed as a result of the combination of solidification shrinkage paired with the local self-feeding and the geometric constraints imposed on the component by the mold
The reduction of these defects by a suitable component design and process control is of great interest for a cost-efficient production. These characteristics are assumed to be the result of a combination of solidification shrinkage, which is paired with the respective local self-feeding and the geometric constraint imposed by the mold on the component

Summary

Introduction

Distortion, residual stresses, and hot cracks are decisive quality characteristics of cast parts and, depending on their characteristics, facilitate the need for additional finishing steps and rejects. The heat transfer coefficient (HTC) between mold and component, which has already been considered as a possible major influencing factor, was analyzed in this project in several separate studies [1,2,3] In addition to these primarily experimental studies, in closely related subprojects, the working group is developing numerical methods to advance the coupled thermomechanical simulation on both the macroscale and the microscale [4,5]. An algorithm for optimizing the cooling channel layout to the local cooling requirements in plastic injection molding is developed in another sub-project This is based on the hypothesis that a homogeneously solidifying component develops the lowest distortion [6]. A recognizable potential became apparent as well as limitations in transferability, which are to be expected due to strongly differing thermophysical material properties between plastics and metals [7]

Methods

Results

Discussion

Conclusion