Abstract
Additive Manufacturing (AM) enables greater geometrical flexibility in engineering design than conventional manufacturing methods, allowing parts to be customized for individual needs, as well as producing less waste material. However, partially bonded powder particles attached to the surfaces limit the usefulness of parts for a range of engineering applications. In order to enable more widespread use of AM, surface modification techniques are required which allow parts to be suitably finished for the requirements of different applications.Additive Manufacturing (AM) enables greater geometrical flexibility in engineering design than conventional manufacturing methods, allowing parts to be customized for individual needs, as well as producing less waste material. However, partially bonded powder particles attached to the surfaces limit the usefulness of parts for a range of engineering applications. In order to enable more widespread use of AM, surface modification techniques are required which allow parts to be suitably finished for the requirements of different applications.
A range of surface modification techniques exist which have been proven capable of improving the surface quality of AM parts. Each technique has its own set of benefits and limitations in terms of surface quality, geometrical flexibility, and the impact of the technique on the material properties. For this reason, there is no one-size-fits-all solution to surface modification for AM. Instead, it has been proposed that these techniques should be treated as a surface modification toolkit, from which techniques can be selected for the individual requirements of a component and its application. This research aims to develop and test a surface modification technique which could address some of the limitations of existing techniques.
In this research, a set of candidate techniques are tested during preliminary experimentation, and from these, the Abrasive Vibratory Finishing (AVF) technique is selected for further testing. Experimental and computational techniques are employed to determine the surface modification capability of the technique on AM Ti-6Al-4V. An image processing tool is developed to allow quantification of the removal of partially bonded powder particles from the surfaces. Computational Fluid Dynamics (CFD) is used to gain further knowledge of the process mechanisms, and to understand the impact of different parameters on the technique.
The research shows that the AVF technique is capable of removing partially bonded particles from AM components, particularly from surfaces perpendicular to vibratory motion. The surface modification capability can be improved by increasing abrasive grit size. CFD modelling suggests that the process could be further improved by separately varying frequency and velocity of the vibrations. The research has also highlighted the fundamental difference between processing of AM surfaces and non-AM surfaces due to the variation between specimens, and the stress concentration created at the attachment points of individual particles and agglomerates.
| Date of Award | 13 Feb 2019 |
|---|---|
| Original language | English |
| Awarding Institution |
|
| Sponsors | Engineering and Physical Sciences Research Council & Renishaw plc |
| Supervisor | Alborz Shokrani Chaharsooghi (Supervisor), Stephen Newman (Supervisor) & Vimal Dhokia (Supervisor) |