3D Printing Metal Parts? Avoid These 3 Disasters

GUEST POST: Nils Keller, Additive Works

With additive manufacturing, you can create large, complex freeform parts from metal powder. But don’t skip the simulation step or your parts may cost more time and money than you ever planned.

One reason for that is the physical phenomenon of contraction. As the powder cools down, contraction can wreak havoc on your printed object, depending on the actual geometry and its continuums mechanics.

In this article we discuss three common unwanted outcomes in metal 3D printing caused by contraction, all of which can be easily avoided by running simulation well before you start physical manufacturing.

Crashing Print Recoaters

In metal 3D printing, the printed layer height is usually between 20 and 200 µm. So, the deformation of one layer usually won’t affect the recoating of the next layer.

However, part geometry consists of thousands of layers, and minute deformations can add up. In fact, together, they can grow larger than a single layer size. If such a deformation occurs in the build direction due to weak or missing fixation of a region, the recoater will crash into the part when it tries to apply the next powder layer.

If this happens, you’ll have to restart the job with a better fixation of this region, losing time and wasting materials.

Image: Deformation in lower layer leads to recoater crash.

Cracks

Large or massive parts can crack at the build plate, within support structures, and in the part itself. This usually happens in regions like corners, where much plastic strain is induced, damaging the material.

Once this occurs, the contraction by new layers printed on top of the crack can result in heavy distortions since a mechanical fixation no longer exists.

A further crack could even result, leading to more imprecise shapes, which in turn can, again, cause recoater crashes (especially in regions that move upward out of the powder bed).

Image: Cracking and delamination can occur in regions like corners where too much plastic strain has been induced.

Deformed, Unusable Parts

Speaking of misshapen objects, the overall part itself may be unacceptably deformed. Although the print resolution is below 100 µm, deformation that occurs during the process can be much higher due to the continuums mechanical effects of the printed geometry.

This problem may prove even worse for geometries that have spring-back effects due to a stress-relaxation during the cutting from the build plate. Depending on the part size and material, deviation in the range of centimeters can appear, preventing the printed part from being usable at all.

Fortunately, none of these problems is insurmountable. You can avoid recoater collisions and cracking as well as compensate for deformation with simulation tools that can compensate for the calculated deformation on the part geometry before printing.

Image: Unintended deformation occurs for multiple reasons. 

Try Amphyon for Creo 7.0

For metal 3D printing simulation, the Amphyon for Creo Plugin by Additive Works is now available. Carry out simulations as part of the print preparation within the tray and pre-deformed models will automatically replace the originals for near-net-shape additive manufacturing.

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