Page 33 - 3D Metal Printing Fall 2018

AM Insights 3D
Part AM Material Material Post- Functionality Processes Requirement Properties Processing
Inspection
• Structural
• Thermal
• Functionally
graded • Size
• One off vs. production
• Tooling vs. functional component
• Durability
• 7 different AM technologies to choose from
• “n” different OEMs to choose from
• Strength
• Temperature
• Biocompatibilty
•Dueto temperature gradients, as- built material properties can be anisotropic
• HIP/heat- treatment required to achieve properties
• Support structure
• Near-net-shape components
• Post-machining
• Tolerance callouts • Surface
finishing
• NDE methods for inspection of complex features
• Feature sizes • Datum
reference features for inspection
• Metrology for complex features
Fig. 2—Key characteristics and factors related to design of AM parts.
only a rapid-prototyping tool, one must look at the bigger picture before making a business case for its use.
Challenges and Potential
While AM processes enable the cre- ation of never-before-seen innovations, many designers remain fixated on con- ventional designs and traditional DFM/DFA practices, not on designing AM-friendly parts.
Every AM process offers its own set of unique capabilities, but manufacturers must creatively design components to see the benefits of these processes. For example, metal powder-bed fusion (PBF) processes enable easily manufac- tured conformal channels, which would be difficult, if not impossible, using con- ventional subtractive methods. Howev- er, designers must understand that sup- port structures are not required during a PBF build. Designing for AM requires an understanding of the complete manu- facturing cycle, including post-process- ing as well as post-process inspection of parts. Currently, few guidelines exist to help designers make informed AM- design decisions.
Even so, there’s no denying that AM continues to gain momentum. While available CAD-software packages are not yet fully equipped for AM design, some conventional CAD providers are working toward providing robust AM design tools. Most have topology-opti- mization capabilities that go beyond being mere guidelines for designers. Meanwhile, AM process-simulation packages are becoming more reliable. Perhaps most importantly, 3D-printing programs at schools and colleges are producing a new generation of engi- neers with a new design mindset.
The potential of AM technologies is just beginning to be uncovered, and designers have an important role to play in bringing this technology into the mainstream. 3DMP
requirements of the part. Also, today it is possible to build complex, intricate shapes such as naturally optimized cel- lular structures that offer high strength- to-weight ratios, objects with varying material density, and mechanical meta- materials wherein the mechanical prop- erties of the part are determined by its shape rather than the composition of the material used.
• Customized part designs. AM makes customized part design and production a viable, cost-effective option, as one does not have to consider tooling or other such auxiliary costs when making changes. The biggest market for custom part designs is the consumer-goods industry. Other industries benefitting from the ability to fabricate custom part designs include the medical and the maintenance, repair and overhaul industries. One now can design patient-specific implants and reverse- engineer and print legacy parts no longer in production.
Making the Case for AM
The possibilities of what can be fabri- cated using AM are unlimited. However, not every part is meant to be additively manufactured. Instead, AM must be viewed as another tool in the manufac- turing tool kit of any organization. The technology enables new and efficient design, but does not necessarily replace well-established traditional manufac-
turing processes. To really make a busi- ness case for additive, one must identify niche applications that leverage the unique capabilities that AM has to offer. Material, complexity, size, assembly, tol- erances, cost, tooling, logistics and pro- duction time are a few of the things to be considered before identifying poten- tial applications for AM.
Important questions to ask before starting the AM journey:
• Do current manufacturing-process constraints limit part performance?
• Can subcomponents be merged to avoid assembly?
• Can the quantity of joints be minimized?
• Can we save weight and material while achieving the same functionality? • Do we need extensive tooling to
manufacture the part?
• Can new material combinations
increase part performance?
• Can part durability be maximized? Once an application has been identi-
fied as a potential AM candidate, one consider a few more things before redesigning the part (Fig. 2). Seven dif- ferent ASTM-identified AM factors each have their separate characteristics. A designer must be aware of what each offers, while also being cognizant of the post-fabrication processes that apply to the component before it arrives at its destination. While AM is way beyond
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