Additive Manufacturing: Exploration of Porosity and Form Features Using Layer by Layer Deposition

Abstract

Aerospace companies use high-strength metal alloys like Inconel or Titanium which could be very difficult to fabricate using conventional methods. The current manufacturing techniques result in significant waste. Additive Manufacturing (AM), in its current state is not sufficiently understood, nor characterized such that conventional design practices and process qualification methodologies can be used. In addition, AM cannot be considered for the manufacture of aircraft components unless the process is stable and controlled. The mechanical properties of fabricated parts require to be characterized to demonstrate their invariability. The laser deposition using complex geometries is a challenge. In addition, the structural performances of AM parts have to be proved. Inherent in these requirements is the need to develop a process specification which requires the monitoring and control of key raw materials, consumables, and process parameters; the development of a fixed practice for each of the AM process. Several procedures are required in order to understand how additive manufacturing works using advanced and complex design models. The ability to adopt AM to the production of components is not only predicated on the ability of AM to be competitive with conventional manufacturing methods in terms of cost, but also on its ability to deliver parts with repeatable mechanical performance. The objective of this paper is to define and characterize the limitation of various complex geometries using additive manufacturing. The experimental research involved the creation of a number of specimens using direct metal laser sintering process, examination of their form features, documenting DMLS geometry limits for the form features and finally the creation of calibration models that can be used in aerospace design manuals.