Avoid Defects in the Powder Bed Fusion Process with Printability Maps

New Video Discusses Printability Maps in AM Module

In a new in-depth video, Thermo-Calc Software discusses printability maps in the AM Module, including what printability maps are used for and the criteria used in the AM Module to determine the likelihood of the defects. The video also demonstrates how printability maps are simulated in the software and concludes with a discussion of the results.

Watch the video to learn about printability maps in the AM Module or continue scrolling to read more about them. 

What are Printability Maps 

During the Powder Bed Fusion process, three possible defects can occur based on the power and scan speed, as well as the powder thickness and hatch distance: keyholing, lack of fusion, and balling. When manufacturers work with a new material, they develop printability maps, also called process maps, to identify the processing conditions that are optimal to minimize the likelihood of these defects. 

Printability maps are generally made by creating a grid of experiments that vary the power and scan speed to get a real-life map of the results. For example, the printability map shown in Image 2 consists of a six by six grid, where each square represents a cube that has been printed, polished, and the porosity measured. By combining the results from all the thirty six experiments, one can see a map of the porosity. 

In the lower right corner of the printability map, where there is high scan speed and low power, one can observe uneven porosity (indicated in red) resulting from incomplete melting of the powder, which is known as lack of fusion. Conversely, in the upper left section, where energy density is high due to elevated power and reduced scanning speed, the powder melts completely; however, this can lead to keyholing and keyhole porosity. In the central area, highlighted in green, a fully dense material with minimal to no porosity is evident. To mitigate the risks of keyholing, lack of fusion, and balling defects in this specific material, manufacturers should use the power and scan speed combinations found in the green-highlighted region.

Simulate Printability Maps in the Additive Manufacturing Module

The Additive Manufacturing Module in Thermo-Calc enables users to produce printability maps with simulations, rather than relying only on experimental methods. This is done by running many steady state simulations that vary the power and scan speeds. For each simulation, the melt pool width and depth are generated, as can be seen in the right columns in the center of Image 3. Users then select the criteria used to define when the various defects will occur and plot the results to identify the ideal processing parameters. The white area in the center of the plot in Image 3 represents the optimal power and scan speed combinations for this particular material, powder layer thickness, and hatch distance. 

Simulate Any Alloy System

Unlike other simulation tools, the Additive Manufacturing Module calculates thermophysical properties directly in the program for any alloy system. This allows users to run simulations for any material without needing to provide external data. As a result, manufacturers can create printability maps for their specific alloys regardless of the data they have available. Alloy systems can even be saved in the program for repeated use. The alloy dependent physical properties included in the program include apparent heat capacity, enthalpy, density, driving force of evaporation,  volume, surface tension of liquid, thermal conductivity and viscosity.

Compare Results to Experimental Data

The Additive Manufacturing Module in Thermo-Calc also allows users to import experimental data into the program to compare it to the simulated results. This feature ensures that the results generated by the software are accurate for the user’s machine and material. In Image 3, the experimental findings are indicated by green and red letters, where ‘K’ denotes keyholing and ‘C’ signifies lack of fusion. In the plot, green labels correspond to experiments without defects and red labels indicate experiments that resulted in defects. As can be seen, the experimental data closely matches the calculated results, highlighting the accuracy of the module.   

Find Out if Printability Maps are Useful for You

To learn more about printability maps and the Additive Manufacturing Module, we invite you to contact us to schedule a free consultation. You’ll meet with one of our experts to discuss whether printability maps can assist in your Additive Manufacturing. 

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