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In focus: Carpenter Additive
From atomisation to analysis: How Carpenter Additive is delivering improved material reliability, economics and quality Metal Additive Manufacturing is a complex technology in which users struggle with materials reliability and quality on a daily basis. Here, William Herbert, Director Technology and R&D - Carpenter Additive, a division of Carpenter Technology, looks at how the company combines a 130-year heritage as a leader in speciality alloys with modern, digital solutions for powder management and material traceability, and supports the AM supply chain end-to-end by developing advanced materials, improving process economics and quality, and reducing risk in production applications.
The dreaded message came through early on a Friday morning from the operations supervisor: “Build failure occurred at approximately layer number 3000, almost 90% of the way through the run.” The engineering team had been monitoring the Laser Powder Bed Fusion (L-PBF) machine as it quietly hummed all week, checking its critical process variables like the vital signs of a patient. The sizeable, valve-like component slowly taking shape in the build chamber bore all the hallmarks of a good additive part – intricate fluid flow features, hard-to-reach internals and long lead times for its cast predecessor. The team had spent days preparing the file, optimising the layout, analysing and screening the high-purity stainlesssteel powder to be used, identifying potential pitfalls and attempting to avoid them through careful setup. Once the build began, the team had looked through the small window into the machine’s build chamber once every half hour to check whether the laser was still sweeping and sparks still flying. The build was
Vol. 5 No. 4 © 2019 Inovar Communications Ltd
in the final stages of its eight-day sequence when the powder recoater blade scratched on a deformed part feature – a shard of metal jutting out of the powder bed. A set of instructions was calmly issued back to the operators: “Stop the process. Allow the platform to cool, remove the plate and powder.
Clean down the machine and turn it around to start all over again.” But first, the team was called to a meeting to identify the root cause and avoid a recurrence on the next attempt. This first failure had cost a week of valuable labour and machine time and a tight delivery schedule was frustratingly affected.
Fig. 1 A late build failure remains an all too common ‘nightmare scenario’ in L-PBF, leading to material, machine time and labour costs as well as delays
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