New Insights into 3D printing of Metals

In yet another breakthrough development, 3D printing has opened new avenues for engineers and compelled product designers to reimagine what is possible. The ability to print complex metallic parts using advanced alloys is undoubtedly impressive but has its own flaws.

Scientists at Heriot-Watt University in collaboration with Argonne National Laboratory and Carnegie Mellon University shed light on the process with the promise to make metal 3D printing increasingly feasible for manufacturers and more sustainable.

Additive manufacturing how 3D printing is technically referred to encompass a variety of material processing techniques, of which laser powder bed fusion is most widely adopted. It works by transmitting thin layers of metallic powder particles that are joined together through intense heat transmitted by high-powdered lasers. But the process can lead to creation of tiny holes that weakens the overall structure.

This is a key drawback for industry, especially when highly-reliable components are required on a consistent basis. In the last three years, scientists at the Institute of Photonics and Quantum Sciences, Heriot-Watt University have undertaken a research project that examined fundamental physics behind LPBF process, and how this can be used to alleviate defects in printed parts.

The research imagines the interplay between all states of matter present when a laser interacts with metallic particles, stated one of the research associates.

Meanwhile, during additive manufacturing, high-powered laser when applied to metal will result in a small pool of liquid metal as the particles combine together. During this stage, a minute amount of metal vaporizes and presses against the liquid to create a cavity at the center of the melt pool.

Often referred to as keyhole, the cavity can become unstable and collapse to form pores in the material.

3D Printing now finds use to manufacture energy-saving gas turbines, say experts

In business environments, among a slew of completely new range of possibilities of 3D printing, production of new turbine buckets is one. However, 3D printing is often associated with internal stress in mechanical components, which in the worst case, can lead to cracks.

Following a research initiative, a research team has been successful to use neutrons from the Technical University of Munich. The success to use the source of research neutron for non-destructive detection of internal stress is a key achievement in the improvement of production processes.

In fact, for 3D printing, in mechanical environments, gas turbine buckets have to handle extreme ambient conditions. For example, at high temperatures and under high pressure gas turbine buckets are subject to tremendous centrifugal forces. Thus, to maximize energy yield further, the gas turbine buckets need to hold temperatures which is actually higher than the melting point of the constituent material. To enable this, hollow turbine buckets are used which are air-cooled from inside.

Interestingly, the gas turbine buckets can be made employing laser powder bed fusion – a step by step adding manufacturing technology. To get started, the starter material in powder form is added layer by layer by selectively melting using laser. For example, in avian bones, the intricate lattice constructin inside the hollow turbine pockets provides necessary support to the corresponding part.

“Meanwhile, it would be impossible to create components with such intricate structures using conventional methods such as milling or casting,” stated ax expert at the German Federal Institute of Materials Research and Testing.

Nonetheless, the highly localized heat input of the laser and rapid cooling of the melt pool in 3D printing lead to residual stress in the material.

Moving 3D Printing Platform could help cut Cost and Material Waste, opine researchers

3D printing can revolutionize product design is increasingly being accepted. The technology is potent to revolutionize the manufacture and design of products across a vast range of fields, including 3D printed dental products, customized consumer products, and bone and medical implants.

On the downside, 3D printing creates a large volume of expensive and unsustainable waste and is time-intensive, thus, making it difficult for the adoption of the technology on a large scale.

For example, for custom objects using 3D printer, especially unusually shaped ones, the technology needs to support printed stands to balance the object. This is because 3D printing involves layer-by-layer creation of the object that helps maintain its integrity. However, after printing, the supports need to be removed manually, which requires hand finishing that can result in surface roughness or shape inaccuracies. Moreover, the materials used to make the supports often cannot be reused, hence discarded, which contributes to the escalating problem of 3D printed waste material.

To address this, in a maiden attempt, researchers at the Viterbi Daniel J. Epstein Department of Industrial and Systems Engineering, USC have fabricated a low-cost reusable support method. The effort carried out is to reduce the need for 3D printers for wasteful supports, thus, improving the cost-effectiveness and sustainability of 3D printing to a great extent.

Meanwhile, traditional 3D printing used Fused Deposition Modeling technique, which involves layer-by-layer printing directly on a static metal surface. Conversely, the new prototype of 3D printing uses a programmable, dynamically-controlled surface fabricated of moveable metal pins to replace the printed supports. In this arrangement, as the pins rise, the printer progressively constructs the product. The testing of the prototype revealed to have saved nearly 35% material to pint object, explained the lead researcher.

3D Printing yields advantages for Radar Technology, find researchers

In an effort to advance radar technology and enable its new applications for the U.S. naval forces, scientists at the Naval Research Laboratory, U.S. have developed and tested 3D printed antennas and arrays.

The newly developed 3D printed components make them attractive for a few features. Firstly, these are lightweight and their rapid production make them an attractive alternative to traditional manufacturing of antennas for radar technology. On top of this, traditional manufacturing of antennas for radar technology requires expensive materials and specialized equipment.

“In fact, 3D printing is useful in many ways. It allows to produce rapid prototypes and attain multiple design iterations very quickly and minimal cost,” said one of the research associates. Furthermore, the lightweight of 3D printed components also allow to take the technology for new applications, wherein heavy weight of solid metal parts was a restriction.

Meanwhile, radar systems perform critical functions for naval operations. For example, parts of antennas and arrays – which are multiple antennas connected to work together as one – may break unexpectedly or wear out to require replacement. Conventionally, broken or worn out parts are either ordered or machined intricately out of metal, which, sometimes may take several weeks to produce.

On the other hand, using 3D printing, components for radar technology such as cylindrical array  can be produced within hours that take several days using traditional methods. Importantly, cylindrical arrays produced using 3D provide a 360-degree visibility.

Besides production, 3D printing has other benefits too. The relatively low cost of 3D printing materials enables researchers to check multiple versions of components at minimal overhead. The improved prototypes can then be produced in machines using traditional methods.