(9f) Simulating Powder Handling Processes in Additive Manufacturing Using the Discrete Element Method

Additive Manufacturing is a rapidly advancing manufacturing area that enables users to produce complex parts in a short amount of time. One common approach to AM in industry involves the deposition and selective sintering/melting of successive layers of metallic powders. Through repeated build-up of powder layers, complex metal parts can be produced.

There are a wide range of metal powders available for AM production and each has its own characteristics. During printing a powder must be stored, transported, and processed within the printing equipment to produce the final part. Each of these stages need to be performed efficiently by the printer to ensure an optimum printing process.

The specific composition and behavioral traits of the powder used in AM is highly influential on printer set-up and resulting part manufacturing quality. Introducing a new powder into an AM process means that the set-up of the printing device needs to be configured to handle this new material effectively. Because of the variability of powder properties, flowability and susceptibility to environmental conditions, it is not straight-forward to make decisions as to how to reach the optimal configuration. At present, a common method to adjust printer set-up to account for the influence of a specific powder requires trial and error testing, or a reliance on know-how from previous work with the same printer and powder combinations. This takes time and extends the overall part production cycle.

Discrete Element Modelling (DEM) is a simulation method for recreating bulk and granular material behaviors in a virtual environment. It is a method used in other powder-focused industries, such as pharmaceutical, to provide engineering insight into powder handling and processing operations. By using DEM simulation, engineers can test design and process concepts and extract meaningful information from virtual versions of their material and equipment to help in the decision-making process.

The same opportunities exist in AM, and such a simulation method offers engineers an alternative to physical trial and error testing when trying to understand how key stages in part production will perform. In this presentation we will discuss the application of DEM, using EDEM software, to the additive manufacturing print process. Examples will be given to demonstrate how DEM can be used to help engineers understand the performance of powder delivery systems, as well as gaining insight into metrics such as powder porosity variation during the powder-layering process.