Fraunhofer ILT sets standards for 3D printing

27 Jul 2021

Studies of best imaging sensors for powder bed fusion technique will improve efficiency.

Fraunhofer Institute for Laser Technology (ILT) has launched a project intended to help bolster and improve international standards related to 3D printing.

In particular the Institute will work towards standardization of machine condition monitoring in laser beam powder bed fusion (LB-PBF).

It is focusing on selecting and qualifying the best imaging sensor technology that can be used to monitor the condition of LB-PBF systems, and ultimately the Institute will derive cost-reducing recommendations for end users from the data.

This work is supported by an award from international standards body ASTM International, one of two new awards it has made concerning standards in the 3D printing sector.

ASTM sought to "generate data required to support a new standard for monitoring the health status of optical systems in LB-PBF machines. This work has potential to improve the reliability of additive manufacturing systems while reducing maintenance downtime and costs."

The other new ASTM award was to the National Research Council of Canada to investigate ways to monitor the moisture content in feedstock materials.

LB-PBF is a selective laser melting technique in which a high power-density laser is employed to melt and fuse metallic powders into solid items. Recent efforts to enhance the quality and output of LB-PBF techniques have included work at Renishaw on optimized modelling and build preparation methods, to improve the accuracy of simulations and predict any distortion that may arise.

Fraunhofer ILT itself created a spin-out, Laser Melting Innovations (LMI), in 2017 with the aim of developing an industry-ready low-cost laser powder bed fusion platform. LMI won the 2019 formnext Start-Up Challenge for its efforts, and its Alpha 140 platform was brought to market in 2020.

Let users make informed decisions

The new project reflects the fact that optical systems can readily become contaminated during LB-PBF operations, and must be regularly cleaned as a preventative measure. The increasing number of optical systems and the ever-higher laser powers used in LB-PBF have aggravated this problem, noted Fraunhofer ILT.

"The load, probability of failure and maintenance effort of optical systems are increasing, while users still have to cope with maintenance guidelines based on little experience with previous system generations," commented Niklas Prätzsch, project manager in the Institute's Laser Powder Bed Fusion competence area.

"Manufacturers' current maintenance guidelines are often still far too conservative. In contrast to long-established manufacturing technologies, there is only a comparatively small database available as a basis for making decisions whenever maintenance cycles need to be determined."

Fraunhofer ILT will tackle this by selecting and qualifying imaging sensor technology for monitoring highly loaded optical systems of LB-PBF machines. It aims to help end users independently assess the condition of optical systems and plan maintenance cycles by using improved information about the actual condition of the system.

The goal is a standardized decision-making best-practice guideline that recommends to the end user when and how to conduct maintenance or calibration, reducing the time previously spent on servicing and maintaining optical systems.

"We are providing end users with recommendations that simplify their use of cost-effective imaging sensor technology for condition monitoring of optical systems in LB-PBF system," said Prätzsch. "Based on the data, they can then make informed decisions about whether or not maintenance is necessary."