Case Study - Post Processing of Metal Additive Manufactured Parts

The Problem

Develop a cost effective Mass Finishing solution which benefited the customer by reducing processing times and producing a repeatable and quality additive manufactured product.

The Aim

The AM parts have been built using SLM or EBM processes. Hence these required intensive manual finishing, to remove support structures and to smooth down rough surfaces. Our objectives included:
  • Identifying a cost effective finishing process for the external surface of the part
  • Develop a finishing process for the internal surface of the part

Post Processing of Metal Additive

The Process

  • Trials have been carried out where it has been determined that the most efficient equipment is the Centrifugal High Energy Finishing machine to achieve sub 1µm RA surface finishes.
  • Further trials have been conducted by both teams to determine the optimum machine parameter settings to process additive manufactured materials like Ti6Al4V

Technology used

High energy machines are used to reduce surface roughness, deburr and polish parts. The action of these machines relies on the high “g” force and velocity at which the media chips come in contact with the processed components. In most cases, the results achieved via high energy finishing cannot be achieved in a standard vibratory process. This particularly applies on applications that include achieving a high surface finish, a mirror finish and the rapid removal of manufacturing defects.

Our high energy technology is known to be significantly faster than traditional finishing methods and produces superior finishes. It is one of the most efficient batch finishing methods. When processing large or fragile additive manufactured components, individual compartments within the barrel ensure parts are processed without the concerns of any contact. This method ensures zero risk of impingement.

The process involves using the correct machinery, media and compound. As the geometry of the additive manufactured parts can usually be intricate, our engineers have developed  media in different shapes and sizes, thereby ensuring consistent finish. The media also comes in a variety of abrasive grades, starting from low abrasive to super finishing. Media hardness is also a critical aspect of the process parameter.

Compounds comprise of abrasives, brighteners, lubricating agents, cushioning materials and cleaning agents. Some of the applications include descaling, inhibiting rust and corrosion of parts and brightening. Our  compounds reduce media costs and process time. The finishing compounds for the process are biodegradable and environmentally friendly.

The result

  • Achieving a Ra of sub 1µm in 5 hours, which is 80% faster than vibratory finishing.
  • Achieving a Ra between 2µm to 3µm in approximately 30 minutes
  • From reducing surface roughness, to deburring and polishing these are just a few of the applications that have been achieved via the high energy finishing process.
  • The project provided further information regarding surface finish parameters, component weight loss, media weight loss, effectiveness of using media with different abrasive grades and hardness.

Benefits

  • 46% cost savings on the finishing process for MTC in comparison with outsourcing
  • The technology offered consistent and repeatable results
  • Created opportunity for both companies to work with other businesses in the industry