ADDITIVE MANUFACTURING is the magazine devoted to industrial applications of 3D printing and digital layering technology. We cover the promise and the challenges of this technology for making functional tooling and end-use production parts.
Issue link: https://am.epubxp.com/i/629211
AM / The Possibilities of EBAM additivemanufacturing.media 25 The view that says additive-manufactured metal parts are necessarily small parts is a view that assumes a particular type of addi- tive machine. That is, that view assumes a powder-bed machine—a machine in which a laser or electron beam moves through a sta- tionary bed of powder metal to create each incremental layer of the part. But this is not the only way to do metal additive. An alterna- tive involves machines in which the material is not in a bed, but instead actively fed. The material supply travels with the beam head, so the size of the part is limited only by the travels of the machine. Sciaky, based in Chicago, Illinois, is an example of a company making systems for achieving additive manufacturing through this kind of material deposition. In this company's process, which it calls Electron Beam Additive Manufac- turing or EBAM, wire feedstock is the raw material, and this wire is fed into the path of an electron beam to additively build parts and features. This method of material deposition is an adaption of welding systems the company has produced for decades. Proprietary closed-loop control over parameters such as temperature and material fow allows it to build 3D structures. The company introduced this variety of additive manufacturing in the early 2000s, and it reports that its ad- ditive machines (used by the company itself or by its customers) have so far deposited more than 18,000 pounds of titanium alone. The contrast between this company's additive process and a powder-bed process is worth making. Because EBAM lays down material in a bead, it does not produce forms as fnely detailed or as near to net-shape as what a powder-bed process can achieve. However, the deposition process permits larger forms, as mentioned, and thanks to the deposition rate of the bead, the EBAM process is faster as well. A cylindrical test part that would have taken 12 hours to build with a powder process took 10 minutes to build with EBAM (see photo). Change-over between jobs is also faster on the EBAM machine, because material change-over requires just swapping in a diferent spool of wire. Again, the comparison with powder-bed is worth making, but it is germane only to a point. Ultimately, these two diferent additive machine types will be used in distinct and separate applications. The far more meaningful comparison is actually between EBAM and forging. Forging is the typical way that near-net- shape forms are made for large parts made of hard metals such as Gun Motions Wire Feeder Re-solidifed Alloy Direction of Part Motion Electron Beam Molten Alloy Puddle Prior Deposit Substrate Process Coordinates System Z Y X EB Gun Material deposition permits fast build time. This test cylinder, around 10 inches in diameter, was grown in only 10 minutes. In the EBAM process, material is fed into the path of the beam. Because the material stock travels with the beam head, large machine travels are possible.