Industrialisation of Powder Metal Process Simulation
Session Chairs:
Mr Peter Kjeldsteen (Sintex, Denmark)
Prof Hans-Ake Haggblad (Luleå University of Technology, Sweden)
Introduction
Mr Peter Kjeldsteen (Sintex, Denmark)
Current Development in Feedback Control Applied onMetal Forming Processes
Ass. Prof. Benny Endelt (Department of Materials and production, Aalborg University, Denmark)
Manufacturing technology and especial materials processing is characterized as highly complex and non-linear processes which are very difficult to analyse using classical analytical methods and the process and tool designs have therefore traditionally been dominated by experience, rule of thumbs and trial and error approaches. During the last two decades finite element analysis has gained a foothold within the area and is now considered the workhorse driving the development of new manufacturing processes and technologies. The ability to simulate and model complex non-linear manufacturing processes is used extensively in leading industry during the product development cycle taking into account process limitations and possible process optimization.
The development and improvement in manufacturing technologies are based on the ability to predict and thereby increase process robustness and component quality. The predictive capabilities have been the main focus in the industry, among software developers and scientists for more than two decades. This joint effort has provided a huge improvement in the results obtained by the finite element simulations - the drawback is that the models are getting more complicated and the number of constitutive parameters used to describe e.g. the material behaviour, has increased significantly. Moreover, there is no evidence that the parameters can be regarded as constant and significant variation in the material parameters from batch to batch has been reported, additionally both material properties and friction conditions are temperature dependent.
Simulation of Metal Injection Molding Processes
Dr Achim Wendt (Element22, Germany)
Metal Injection Molding of Ti-alloys includes the process steps: Feedstock preparation – Injection molding – Debinding – Sintering. Although each of these steps is essential for the desired product quality, it is crucial to avoid defects induced by molding since these will be transferred into the sintered component. Simulation of injection molding is an appropriate tool to avoid such defeats. The presentation will www.europm2017.com highlight the experience of the first year of regular use of MIM-simulation at Element 22.Typically, a first mold filling simulation is performed after request for quotation. At that stage, a simplified model is applied using 'standard' process parameters. This simulation shall quickly answer questions whether the mold can be properly filled, if major defects are expected and how to resolve them. After order placement, more detailed simulations include effects of mold tempering, filling speed, mass temperature, and shall eventually yield optimised process parameters with respect to product quality. This procedure will be demonstrated using appropriate examples.After a year of regular usage the main conclusions are: proper araterial properties are essential for reliable results; each simulation gives additional insight into the process; simulation is well accepted by the development and production teams and contributes to process improvement.
Simulation of Metal Powder processing using LS-DYNA®
Dr Mikael Schill (Dynamore Nordic, Sweden)
In the last decade, Simulation Based Design (SBD) has become a crucial tool in design and manufacturing of a vast number of products. This is especially true for the automotive industry where the companies are moving away from costly prototypes and testing towards a zero prototype design process. The Powder processing industry can benefit from this infrastructure available in terms of pre-processors, computer clusters and solvers. The multi-physics solver LS-DYNA is a very powerful tool in this community since it combines a multitude of Finite Element formulations and solvers that can be coupled and combined to give the user the possibility to solve a wide range of simulation problems in a short timeframe. This is also true for powder compaction and sintering simulations.
The corner stone of the simulations is a material model for metal powder that is used for both the compaction and the sintering process steps. In the compaction step, the powder is compacted and the resulting relative density distribution is calculated as well as the press forces. Due to the large deformations, one has to use a mesh free method (EFG) or an adaptive method with remeshing to avoid element distorsion that will diminish the accuracy. The results from the compaction simulations are then transferred to a sintering simulation where the powder is sintered to full density and the net shape is determined.
The purpose of the workshop is to give the audience an introduction to simulating powder compaction and sintering using LS-DYNA. The necessary input and model preparation will be presented as well as the predicted outcome.
Powder Process Simulations at Luleå University of Technology
Prof Pär Jonsén (Luleå University of Technology, Sweden)
For more than 30 years have Luleå University of Technology been in the field of simulation of powder behaviour in a many different processes like powder filling, compaction, hot isostatic pressing etc. To model the nonlinear behaviour of powder material is a challenge and lot of the work is concentrated on constitutive modelling with advanced models. Development of density distribution, residual stress fields and fracture of green bodies, but also material flow and process analysis of powder filling are main research areas. A number of different numerical methods are used together with a multitude of finite element (FE) formulations and solvers coupled and combined to give possibility to solve a wide range of problems in a short timeframe. Also particle based methods like the discrete element method, the smoothed particle hydrodynamics (SPH) method and the particle finite element method (PFEM) are used for problems with large deformations.
Many different experimental techniques are used for evaluating loads and deformation. Examples where digital speckle photography (DSP) is used to study powder flow during die filling are demonstrated. DSP measurements are comprehended by recording the powder filling process with high speed video equipment. The image series are then assessed using an image correlation method, resulting in velocity and strain field data for the filling process can be visualized. The main advantage is a strain field measurement with high resolution that supports the development of a numerical model of the process. By comparing velocity fields during powder filling from experimental and numerical results it can be concluded that the results are in close agreement. Experimental measurements combined with simulation are powerful tools to increase the knowledge powder processes but also for future product development.
Round Robin
Prof Hans-Ake Haggblad (Luleå University of Technology, Sweden)
