Machinery's Handbook, 31st Edition
METAL ADDITIVE MANUFACTURING PROCESSES
1563
Primary Processing (15.9MJ/kg)
CONVENTIONAL MACHINING Buy-to-fly ratio 8:1
Secondary Processing (8.72 kg)
Final Processing
Finished Part (1.09 kg)
Mill Product (slab)
Machined Product
Ingot
ADDITIVE MANUFACTURING Buy-to-fly ratio 1.5:1
Final Processing Finished Part (0.38 kg)
Electron Beam Powder Bed Fusion
(0.57 kg)
Atomization (14.8 MJ/ kg)
Powder
Fig. 31. Comparative Date for Conventional Machining and Additive Manufacturing of a Titanium Aircraft Bracket (Source: MFT and LIGHTEnUp Team) Unique Capabilities of Metal AM.— For a given metal alloy, the cost of material in pow- der or wire form for additive manufacturing generally is much higher than the cost of bar stock used in conventional manufacturing. In addition, the cost of AM equipment is high and production rate is low, so production costs for AM are high. On the other hand, AM processes do not require tooling and associated production delays, and usually little mate- rial is lost. More important, AM can easily make much more complicated designs than can be made by conventional processes. Conventional manufacturing processes, such as machining, sheet forming, and casting, impose constraints on the design of parts to be made by those processes, as is well known by designers. These constraints control possible configurations when designing a new compo - nent. Additive manufacturing processes remove many of those design constraints, though, despite the hype surrounding these technologies, AM also has limitations. Most limita- tions currently involve feature size and resolution: hole diameter and depth, wall height and thickness, and surface finish. In addition, at a practical level, for most metal AM processes, part features must be such that unused powder can be removed; that is, a completely en- closed hollow chamber must be provided with a hole for removal of internal powder. Nev- ertheless, AM processes provide great opportunity for expanding the designer’s vision. Table 9 compares capabilities of SLM, EBM, BJ, and DED processes for producing metal parts by additive manufacturing. Within the constraints shown, complex configurations can be conceived that would be difficult or impossible to achieve by conventional manufacturing processes. Four promi - nent shapes classes are discussed here, though many other complexities can be explored. Table 9. Comparison of the Capabilities of AM Processes for Producing Metal Parts
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