The process of depowdering is to remove remaining trapped metal powder in the printed parts, which mechanical vibration can push the powder out of the printed parts. In such parts, any residual powder in the parts will hinder its functions. Additionally, if the part is heat treated without depowdering, the powder will be solidified, resulting in blocking the channels.

Heat treatment/ annealing is performed in a vacuum/ inert furnace. The heat treatment cycle is set according to the chemical composition of the material. Heat treatment reduces the internal thermal stress that occurs during printing and improves the mechanical properties of the printed parts. It is important to note that heat treatment is performed before separating the part from the build plate to avoid warping.

After finishing heat treatment process, it’s time to cut off the printed parts from the build plate. There are mainly three ways to deal with the cut-off process, which depends on the parts structures and supports.

1. Manual Chiselling

When the supports of printed parts are weak and minimal, chiselling out the supports can be applied.

2. Bandsaw

Bandsaw cutting requires printing about 5mm of additional material to compensate for blade thickness, which means it will increase the cost if printing large volume materials. Also, bandsaw is not precision cutting. Therefore, the cut surface must be machined for a better surface finish.

3. Wire EDM

As the easiest and most precise method of cut-off, the cut-off line is only 0.2mm diameter, and extra material with a thickness of only 0.25mm needs to be printed to compensate for the wire diameter.

By separating the printed parts from the build plate, it is easier to remove remaining supports on the parts.

1. Manual chiselling is the common way to remove supports. However, the surface finish of the support-removing area needs to be improved if using manual chiselling.

2. For surfaces with underlying supports that require a 2D profile with a good surface finish, using Wire EDM to remove supports is recommended.

3. For complex surfaces with supports beneath and requiring good surface finish, using CNC machining to remove supports is recommended.

Printed parts may require machining such as thread for fastening, holes for mounting a shaft, or a flat surface for butting. Part-specific Jigs and Fixtures are manufactured to clamp the part if needed.

Select the surface treatment technique by the desired type of finish and aesthetic appearance. Surface treatment technique includes vibro tumbling, shot blasting, abrasive flow machining, plating, polishing and micro machining.