Simulation Simulation improves process reliability in Metal 3D Printing

Additive manufacturing makes it possible to produce innovative bionic designs, provided by topology optimizations for instance. With Additive Print, simulation expert Ansys has added a tool for designers and process engineers to its portfolio that makes their job easier.

In additive manufacturing, the layer-by-layer build-up, melting, solidification and cooling are highly demanding processes that determine the properties of the finished component. Particular challenges include the dimensional accuracy of the components, the desired material structure and process reliability that avoids blemishes when the support structures are removed and so-called blade crashes in which the component and production head collide.

Simulation and optimization of the 3D printing process

In order to assure production and product quality in additive manufacturing, Ansys has developed Additive Print, a tool that is specifically addressing designers and process engineers. They can simulate and optimize the manufacturing process for metal 3D printing on a web-based platform.

Gallery

Support structures are created aitomatically

To this end, the STL geometry of the part is uploaded and complemented with automatically generated support structures. If desired, manually defined support structures can also be integrated. The component geometry is automatically rasterized and displayed in the form of voxels, with the user defining the voxel size based on the structure. Local refinements can automatically be used to visualize curvatures. The material properties are selected from a material database or defined and assigned by the user.

Simulation of 3D printing provides information on the deformation of components

Calculation is based on one of the following three approaches:

• Assumed Strain assumes uniform elongation and determines the expected distortion on the basis of the component geometry. The strain is determined by calibration using a reference pressure that characterizes the machine and material properties.

• Scan Pattern takes into account the influence of the exposure strategy and derives a directional strain for each layer. For this purpose, the scan patterns for selected machine manufacturers are read directly by Build Files or generated as part of Additive Print with the Scan Pattern Generator.

• Thermal Strain performs a thermal-mechanical analysis in which the thermal analysis with a resolution of up to 15 μm can visualize the thermal history and thus the accumulated cyclic thermal strain (thermal ratcheting) with high accuracy.

As a result of the analysis, the deformations of the component on the build plate or after detachment from the plate can be determined. In addition, strain results are available to assess the risk of support breakage.

3D Metal Printing

Moulds produced in a 3D metal printer

Additive print provides the following options for minimizing component distortion:

• Alternative process parameters allow an evaluation of how distortion can be minimized by choosing different process parameters (layer thickness, laser power, laser speed, preheating temperature).

• Optimized support structures show how warpage can be reduced by adapting support structures using variable spacing or variable thickness.

• Geometry compensation provides STL files with distortion values. The deformations caused by the manufacturing process are thus taken into account, so that the component geometry in the manufacturing process is as close as possible to the target geometry.

Balancing productivity and quality

With Release 2019.1, Additive Suite offers further functions to increase machine productivity. Laser power and speed are two dominant parameters with which the construction speed can be positively influenced, but which also have effects on the construction quality. Simulation can help to find a better setup than the standard machine setting, which should cover a universal area of application.

A detailed analysis of the process control allows for the adjustment of these parameters and thus to achieve an optimal balance between construction speed and product quality. For example, the melt pool, porosity, heat distribution in the individual layers and grain size and orientation can be considered individually.

This article was first published by konstruktionspraxis.

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Original by Monika Zwettler / Translation by Alexander Stark

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