Latest from Materials

Aleksandr Matveev | Dreamstime
Thiti Tangjitsangiem | Dreamstime
'Availability of new foundry sand is already becoming a challenge, along with the need of providing new solutions to waste management,” according to the director of a metallurgical research center.
Branimir Ritonja | Dreamstime
Automotive cast parts.
Seesea | Dreamstime
Fire photo
Jacek Sopotnicki | Dreamstime
With deoxidized base iron, carbon levels can be increased to 3.30% C and alloying can be completely or nearly eliminated at the same time.
Gefertec GmbH
Gefertec 3DP bearing block

AM Continues to Expand, and So Does the Definition

April 20, 2018
Sales of metal additive manufacturing systems increased by 80% in 2017, propelled by new functionalities and paced by a growing number of practical applications

Industrial manufacturing of metal parts has been underway for centuries, but it has never been more open to reinterpretation. Until the past decade, such manufacturing processes relied heavily on expertise, with options available based on material choice and finished applications. Now, design flexibility and production volumes are infiltrating the decision-making equation, thanks to the growing application of metal additive manufacturing (AM.) 

In the recent publication of Wohlers Associates Inc.’s annual report on the state of the additive manufacturing and 3D printing industry, it’s estimated that 1,768 metal AM systems were sold in 2017, compared to 983 systems in 2016, a nearly 80% increase. (The 344-page Wohlers Report 2018 is available for purchase.) The report noted that the expansion in metal AM system installations was paralleled by improved process monitoring and quality assurance measures in metal AM. More progress on the latter may be expected, the report added. 

Increasingly, manufacturers are becoming aware of the new advantages of producing metal parts by additive manufacturing, and that increase is driving innovation in the engineering and technology that precedes production. Wohlers found that 135 companies worldwide developed and delivered industrial AM systems during 2017, versus 97 companies in 2016. The trend brings with it new systems with open material platforms and faster speeds, often available at lower prices than in the past.

The laser-based, powder-bed processes that have predominated in metal AM technologies are being joined by new options. Gefertec GmbH recently introduced the GTarc machine series, which manufacture metal parts using arc welding technology, one layer at a time, in materials as various as the availability of welding wire. The 3DMP® process is described as cost efficient and high speed, resulting in near-net-shape metal parts, with quality standards comparable to what is achieved with standard manufacturing methods. Once formed, these AM parts are finish machined using standard CNC milling processes.

Another alternative to powder-bed processing is offered by Trumpf, which claims its laser-deposition welding method allows build rates that are 10 times higher than what is achieved by powder-bed AM. 

The Trumpf process is used to apply wear-protection layers to and/or repair components, as well as to create new structural forms. The laser creates a melt pool on a component’s surface, into which metallic powder is inserted via a nozzle. It is particularly adaptable as a follow-on step to CNC milling and turning operations, an approach known as “hybrid manufacturing” because it combines additive and “subtractive” manufacturing. 

Other CNC machine specialists are active in this hybrid realm too, including major CNC machine developers DMG Mori and Mazak.

Another approach to additive manufacturing entirely without lasers uses 3D coating technology. J.G. Weisser Söhne GmbH offers a patented process by which semi-finished material is rotationally imprinted onto a component’s surface, and melted by the friction this generates. According to Weisser, the advantages compared to the laser-based additive manufacturing process featuring a powder bed are that the semi-finished materials are 10 to 30 times more affordable, and the deposition rates are 20 times higher for aluminum and up to 100 times higher for steel. Currently, the process is limited to forming only simple structures.

Hermle Maschinenbau GmbH offers a metal-powder deposition process that does not require any lasers: it’s a thermal injection process in which metal powder is accelerated at very high velocities using a carrier gas, and applying successive layers via a nozzle onto a component surface. There are very few restrictions on the choice of material, as long as it can be powdered, and it is possible to apply up to seven different materials in any ratio on free-form surfaces. It’s also a low-temperature (200°-300°C) process that offers another viable phase for hybrid manufacturing.

The expansion of metal additive manufacturing surely suggests the possibility that it can eclipse certain traditional forming processes, like metalcasting, but the emphasis on hybrid manufacturing suggests something else: the primacy of design in the conception of finished parts, and the necessity of speed and volume in manufacturing, meaning that any combination of set-up and execution is open for consideration.