High Throughput Laser Array Based Additive Manufacturing

增材制造（AM）技术的早期前景有望提供更大的设计自由度，提高生产力水平，最大限度地减少材料使用，压缩供应链，并使生产商能够通过提供增强的产品能力来提高竞争力。基于金属的LPBF AM系统在过去20年中稳步发展，现在代表了数十亿英镑的全球机器，材料和软件市场。它们在许多工业部门中找到了利基小批量应用，在航空航天和生物医学部门的应用范围更广。然而，LPBF AM工艺与传统的制造路线相比仍然很慢，并且相当复杂。它们需要高能量激光束在大型粉末床上的精确聚焦和操纵，以便通过激光熔化将金属粉末固结成三维固体。熔化策略对零件质量起着重要作用。在所有商业系统中采用的单激光束熔化策略遭受熔化不稳定性、低熔化效率和复杂的扫描策略以达到高密度。它们需要高水平的劳动密集型部件特定构建参数细化和耗时的后处理操作。尽管这种生产路线具有明显的吸引力，但在构建速率，工艺稳定性，零件精度，可重复性和零件成本方面仍然存在一些挑战。在这个项目中，我们建议研究几种解决这些基本问题的技术解决方案。为了提高构建速率，我们将通过重新配置激光粉末相互作用过程，从当前的单激光相互作用到大规模激光阵列，来建立一类新的LPBF AM能力。这种方法在多kW领域提供了更高的熔化效率和真正的功率可扩展性。由于激光器阵列易于扩展，20千瓦的系统可以在24小时内提供153公斤的构建速率。这比目前的系统快20倍。我们的方法可以为LPBF AM系统提供世界领先的性能数据。激光器阵列的使用使得有问题的穿孔机制能够被传导限制机制所取代，从而导致工艺稳定性和部件密度的显著增加，通常达到99.99%。更稳定的熔化状态，降低热梯度，减少残余应力，减少零件变形，并最终提高零件精度。将应用过程中计量来检测构建层中的错误，并启用纠正步骤，从而提高过程可重复性并提供正确的第一次生产过程。与传统的LPBF AM系统相比，通过上述创新组合，我们估计可以实现高达80%的部件成本节省。

The early prospects of Additive Manufacturing (AM) technologies promised to provide greater design freedoms, raise productivity levels, minimise material usage, compress supply chains, and enable the producer to attain greater levels of competitiveness by delivering enhanced product capabilities. Metal based LPBF AM systems have developed steadily over the past 20 years and now represent a multibillion-pound global market in machines, materials, and software. They find niche low volume applications in many industrial sectors and somewhat wider applications in aerospace and biomedical sectors. However LPBF AM processes are still slow compared to traditional manufacturing routes and are quite complex. They require precise focusing and manipulation of high energy laser beams over large powder beds in order to consolidate metal powder into a 3-dimensional solid through laser melting. Melting strategies play a significant role in part quality. Single laser beam melting strategies employed in all commercial systems suffer from melt instabilities, low melting efficiencies, and complex scanning strategies to reach high densities. They require a high level of labour-intensive part-specific build parameter refinement and time-consuming post processing operations. Despite the clear attractiveness of this production route, there remain several challenges in terms of build rates, process stability, part accuracy, repeatability, and part cost.In this project we propose to investigate several technology solutions that address these fundamental problems. To improve build rate we will establish a new class of LPBF AM capability by re-configuring the laser powder interaction process away from the current single laser interaction to large scale laser arrays. This approach offers increased melting efficiencies and true power scalability in the multi-kW domain. Since laser arrays are readily scalable, a 20kW system could deliver build rates of 153 kg in 24 hours. This is some 20 times faster than current systems. Our approach could offer world leading performance figures for LPBF AM systems. The use of laser arrays enables the problematic keyholing regime to be replaced with conduction limited regime leading to dramatic increases in process stability and part densities routinely reaching 99.99%. More stable melting regimes with reduced thermal gradients and reduce residual stress, reduce part distortion, and ultimately increase part accuracy. In process metrology will be applied to detect errors in the build layers and enable corrective steps thereby increasing process repeatability and deliver a right-first-time production process. With the combined innovations cited above we estimate that part costs savings up to 80% could be achieved compared to conventional LPBF AM systems.