Given the length of time required for building these larger parts, process reliability is a key factor. The laser powder bed fusion process involves managing and dispersing the high levels of energy deposited on the powder bed to avoid stress accumulation that can lead to deformations of the part and the build plate. Parameters ranging from gas flow velocity and scanning strategies to support structures and printing order must be carefully considered for optimal process security.
Without a proven process, large AM parts are at risk of failure through a variety of factors. Iron-based alloys, for example, are particularly prone to spattering issues, and these pro-blems grow with the thickness of the layer. High process emissions, such as smoke or fumes, can even create excessive porosities or, in the worst cases, a job crash. A wide range of issues can also lead to powder lumps, which can quickly result in scrapped parts. For these reasons, AM machines must be well-maintained and accurately calibrated, especially when they utilize multi-laser configurations.
Gas flow management is highly critical for long building jobs.
From additional machining and inspection to the final separation from the build plate, virtually all large AM parts will require post-processing. As the cost-effectiveness of these parts depends on process simplification when compared to previous strategies, an efficient, fully interoperable workflow that can maintain part reference points throughout production is critical – especially for the tight tolerances involved in the demanding industries where metal AM technology is applied.
A key consideration is separating the part from its build plate, a universal post-processing operation – in some situations, the built part must also be heat treated and machined before final part separation. Conventional solutions are difficult to utilize in this context; vertical-cut EDM equipment rarely can accommodate the large and heavy parts involved, for example. Many AM processes previously used bandsaws with the expectation of finishing the cut surface through post-separation machining, but in addition to creating workholding challenges, this process is incompatible with the nickel superalloys and other materials used in many metal AM applications.
Bandsawing and other parting-off or post-processing operations also create significant issues with heat generation. The thermal effects produced by these subtractive methods can cause microstructural changes and oxidation that damage part integrity. Of course, getting these large, heavy parts into conventional subtractive equipment can be challenging in itself, and without effective process controls, operators risk scrapping a high-value part during the final operations.
A complete solution for large AM part production
To reduce per-part costs and achieve the lowest total cost of ownership, the DMP Factory 500 works as the center of a complete turnkey AM production solution.
Developed to allow users to control the full AM workflow from start to finish, the 3DXpert™ software package can be used for everything from part design and support development to laser scanning strategies and post-build machining programs. For the production of large AM parts, the software’s build simulation tools allow manufacturers to perform multiple build iterations at the virtual level, ensuring that the real-world process is successful on the first attempt. 3DXpert™ even offers print strategy optimization tools that optimize the use of the DMP Factory 500’s multiple lasers with auto-balancing controls that distribute scan paths and print area merges for the shortest printing times that can be achieved given the required part quality and surface accuracy.
System 3R pallets
Whether used as part of an automated workflow with System 3R automation for greater productivity or manually moved between machines and workstations, the System 3R AM tooling is designed to preserve reference points for large, heavy parts throughout the entire production process. BuildPal and BuildPallet printing platforms are available in a range of sizes and materials for application-specific compatibility, while AMCarrier is designed to remain operable even in the event of limited part deformation – all of which can be easily clamped within MILL, FORM, CUT and LASER solutions.
System 3R Tooling for AM for easier post-processing