Diode area melting - a novel re-configurable multi-laser approach for efficient additive manufacturing with enhanced thermal process control

Laser powder bed fusion (LPBF) is an Additive Manufacturing (AM) technique that has in recent years seen a significant increase in industrial usage for the manufacture of high-value end-use components in the aerospace, automotive, and medical sectors. It is widely viewed as a disruptive alternative to conventional manufacturing processes, capable of creating geometrically efficient and complex structures with low material wastage. However, LPBF processing methodology has not evolved in over two decades, using galvo-scanning systems and high power fibre lasers (1070nm wavelength) to selectively melt thin layers of feedstock from a powder bed. This approach creates challenges in regards to LPBF system scalability, processing efficiency (due to poor laser absorption, wall-plug efficiency) and thermal process control accompanied by rapid melt-pool solidification. Poor thermal control can further lead to residual stress development and hot-tearing within components which in turn limits the range of processable alloys available.

In order to overcome limitations associated with state-of-the-art LPBF, we will create the next generation in multi-laser LPBF processes with unrivalled process thermal control, creating a radical step change in additive manufacturing capability. We will build a new manufacturing instrument integrating a highly scalable, wavelength optimised, multi-laser approach known as Diode Area Melting (DAM). This approach will incorporate a laser head with x147 individually addressable laser diodes, operating at absorption efficient wavelengths and low individual power. The diode lasers will be stacked in a unique 2D array enabling advanced in-situ thermal pre/post-heat by activating traversing laser sources immediately before and after the generated melt pool. This instrument will also integrate hybrid laser sources enabling further process control using re-configurable laser processing with galvo-scanning approaches and bespoke large area diode optical pre-heating. Through advanced thermal control this instrument will enable a reduction in residual stress formation and create novel site-specific customised microstructures, a new generation of products with capabilities exceeding those of traditional LPBF.