1、ISO/ASTM 52910:2018(E)Additive manufacturing Design Requirements,guidelines and recommendations1This standard is issued under the fixed designation ISO/ASTM 52910; the number immediately following the designation indicates theyear of original adoption or, in the case of revision, the year of last re
2、vision.1. Scope1.1 This document gives requirements, guidelines and rec-ommendations for using additive manufacturing (AM) inproduct design.1.2 It is applicable during the design of all types of products,devices, systems, components or parts that are fabricated byany type of AM system. This document
3、 helps determine whichdesign considerations can be utilized in a design project or totake advantage of the capabilities of an AM process.1.3 General guidance and identification of issues aresupported, but specific design solutions and process-specific ormaterial-specific data are not supported.1.4 T
4、he intended audience comprises three types of users:1.4.1 designers who are designing products to be fabricatedin an AM system and their managers;1.4.2 students who are learning mechanical design andcomputer-aided design; and1.4.3 developers of AM design guidelines and design guid-ance systems.1.5 T
5、his standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Normative referen
6、ces2.1 The following documents are referred to in the text insuch a way that some or all of their content constitutesrequirements of this document. For dated references, only theedition cited applies. For undated references, the latest editionof the reference document (including any amendments) ap-p
7、lies.2.2 ISO/ASTM Standard:2ISO/ASTM 52921 Standard terminology for additive manu-facturing Coordinate systems and test methodologies3. Terms and Definitions3.1 Definitions: For the purposes of this document, theterms and definitions given in ISO/ASTM 52921 and thefollowing apply.3Additive manufactu
8、ring processes categories3.1.1 binder jettingadditive manufacturing process inwhich a liquid bonding agent is selectively deposited to joinpowder materials. SOURCE: ISO/ASTM 52900:43.1.2 directed energy depositionadditive manufacturingprocess in which focused thermal energy is used to fusematerials
9、by melting as they are being deposited. SOURCE:ISO/ASTM 52900: Note to entry has been deleted3.1.3 material extrusionadditive manufacturing process inwhich material is selectively dispensed through a nozzle ororifice. SOURCE: ISO/ASTM 529003.1.4 material jettingadditive manufacturing process inwhich
10、 droplets of build material are selectively deposited.SOURCE: ISO/ASTM 52900: Note to entry has beendeleted3.1.5 powder bed fusionadditive manufacturing process inwhich thermal energy selectively fuses regions of a powderbed. SOURCE: ISO/ASTM 529003.1.6 sheet laminationadditive manufacturing process
11、 inwhich sheets of material are bonded to form an object.SOURCE: ISO/ASTM 52900: “a part” has been re-placed with “an object”3.1.7 vat photopolymerizationadditive manufacturingprocess in which liquid photopolymer in a vat is selectivelycured by light-activated polymerization. SOURCE: ISO/ASTM 529003
12、.2 Other definitions:3.2.1 design considerationtopic that can influence deci-sions made by a part designer.3.2.1.1 DiscussionThe designer determines to what extentthe topic can affect the part being designed and takes appro-priate action.1This international standard is under the jurisdiction of ASTM
13、 Committee F42on Additive Manufacturing Technologies and is the direct responsibility ofSubcommittee F42.04 on Design and is also under the jurisdiction of ISO/TC 261.Current edition approved July 23, 2018. Published July 2018. DOI: 10.1520/ISO_ASTM59210-18.2For referenced ASTM standards, visit the
14、ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3ISO and IEC maintain terminological databases for use in standardization at thefollowing addresses: IS
15、O Online browsing platform: available at http:/www.iso.org/obp, and IEC Electropedia: available at http:/www.electropedia.org/.4Under preparation. Stage at the time of publication: ISO/DIS 52900:2018. ISO/ASTM International 2018 All rights reservedThis international standard was developed in accorda
16、nce with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.2.2 process chainsequence of man
17、ufacturing processesthat is necessary for the part to achieve all of its desiredproperties.4. Purpose4.1 This document provides requirements, guidelines andrecommendations for designing parts and products to beproduced by AM processes. Conditions of the part or productthat favor AM are highlighted.
18、Similarly, conditions that favorconventional manufacturing processes are also highlighted.The main elements include the following:4.1.1 the opportunities and design freedoms that AM offersdesigners (Clause 5).4.1.2 the issues that designers should consider when design-ing parts for AM, which compris
19、es the main content of theseguidelines (Clause 6), and4.1.3 warnings to designers, or “red flag” issues, thatindicate situations that often lead to problems in many AMsystems (Clause 7).4.2 The overall strategy of design for AM is illustrated inFig. 1. It is a representative process for designing me
20、chanicalparts for structural applications, where cost is the primarydecision criterion. The designer could replace cost with quality,delivery time, or other decision criterion, if applicable. Inaddition to technical considerations related to functional,mechanical or process characteristics, the desi
21、gner should alsoconsider risks associated with the selection of AM processes.4.3 The process for identifying general potential for fabri-cation byAM is illustrated in Fig. 2. This is an expansion of the“identification of general AM potential” box on the left side ofFig. 1. As illustrated, the main d
22、ecision criteria focus onmaterial availability, whether or not the part fits within amachines build volume, and the identification of at least onepart characteristic (customization, lightweighting, complexgeometry) for which AM is particularly well suited. Thesecriteria are representative of many me
23、chanical engineeringapplications for technical parts, but are not meant to becomplete.4.4 An expansion for the “AM process selection” box inFig. 1 is presented in Fig. 3, illustrating that the choice ofmaterial is critical in identifying a suitable process or pro-cesses. If a suitable material and p
24、rocess combination can beidentified, then consideration of other design requirements canproceed, including surface considerations and geometry, staticphysical and dynamic physical properties, among others. Thesefigures are meant to be illustrative of typical practice for manytypes of mechanical part
25、s, but should not be interpreted asprescribing necessary practice.5. Design opportunities and limitations5.1 GeneralAdditive manufacturing differs from other manufacturingprocesses for several reasons and these differences lead tounique design opportunities and freedoms that are highlightedhere.As a
26、 general rule, if a part can be fabricated economicallyusing a conventional manufacturing process, that part shouldprobably not be produced using AM. Instead, parts that aregood candidates for AM tend to have complex geometries,custom geometries, low production volumes, special combina-tions of prop
27、erties or characteristics, or some combination ofthese characteristics. As processes and materials improve, theemphasis on these characteristics will likely change. In Clause5, some design opportunities are highlighted and some typicallimitations are identified.5.2 Design opportunities:5.2.1 Backgro
28、undAM fabricates parts by adding materialin a layer-by-layer manner. Due to the nature of AM processes,AM has many more degrees of freedom than other manufac-turing processes. For example, a part can be composed ofmillions of droplets if fabricated in a material jetting process.Discrete control over
29、 millions of operations at micro to nanoscales is both an opportunity and a challenge. Unprecedentedlevels of interdependence are evident among considerationsand manufacturing process variables, which distinguishes AMfrom conventional manufacturing processes. Capabilities totake advantage of design
30、opportunities can be limited by thecomplexities of process planning.5.2.2 OverviewThe layer-based, additive nature meansthat virtually any part shapes can be fabricated without hardtooling, such as molds, dies or fixtures. Geometries that arecustomized to individuals (customers or patients) can beec
31、onomically fabricated. Very sophisticated geometric con-structions are possible using cellular structures (honeycombs,lattices, foams) or more general structures. Often, multipleparts that were conventionally manufactured can be replacedwith a single part, or smaller number of parts, that is geometr
32、i-cally more complex than the parts being replaced. This can leadto the development of parts that are lighter and perform betterthan the assemblies they replace. Furthermore, such part countreduction (called part consolidation) has numerous benefits fordownstream activities. Assembly time, repair ti
33、me, shop floorcomplexity, replacement part inventory and tooling can bereduced, leading to cost savings throughout the life of theproduct. An additional consideration is that geometricallycomplex medical models can be fabricated easily from medicalimage data.5.2.3 In many AM processes, material comp
34、ositions orproperties can be varied throughout a part. This capabilityleads to functionally graded parts, in which desired mechanicalproperty distributions can be fabricated by varying eithermaterial composition or material microstructure. If effectivemechanical properties are desired to vary throug
35、hout a part, thedesigner can achieve this by taking advantage of the geometriccomplexity capability of AM processes. If varying materialcomposition or microstructure is desired, then such variationscan often be achieved, but with limits dependent on the specificprocess and machine. Across the range
36、of AM processes, someprocesses enable point-by-point material variation control,some provide discrete control within a layer, and almost allprocesses enable discrete control between layers (vat photopo-lymerization is the exception). In the material jetting andbinder jetting processes, material comp
37、osition can be varied invirtually a continuous manner, droplet-to-droplet or even bymixing droplets. Similarly, the directed energy depositionprocess can produce variable material compositions by varyingISO/ASTM 52910:2018(E)2 ISO/ASTM International 2018 All rights reservedFIG.1OverallStrategyforDes
38、ignforAMISO/ASTM 52910:2018(E)3 ISO/ASTM International 2018 All rights reservedFIG.2ProcedureforidentificationofAMpotentialISO/ASTM 52910:2018(E)4 ISO/ASTM International 2018 All rights reservedthe powder composition that is injected into the melt pool.Discrete control of material composition can be
39、 achieved inmaterial extrusion processes by using multiple depositionheads, as one example. Powder bed fusion (PBF) processes canhave limitations since difficulties can arise in separatingunmelted mixed powders. It is important to note that specificmachine capabilities will change and evolve over ti
40、me, but thetrend is toward increasing material composition flexibility andproperty control capability.5.2.4 A significant opportunity exists to optimize the designof parts to yield unprecedented structural properties. Theconcept of “design for functionality” can be realized, meaningthat if a parts f
41、unctions can be defined mathematically, the partcan be optimized to achieve those functions. Novel topologyand shape optimization methods have been developed in thisregard. Resulting designs can have very complex geometricconstructions, utilizing honeycomb, lattice or foam internalstructures, can ha
42、ve complex material compositions andvariations, or can have a combination of both. Research isneeded in this area, but some examples of this are emerging.5.2.5 Other opportunities involve some business consider-ations. Since no tooling is required for part fabrication usingAM, lead times can be very
43、 short. Little investment inpart-specific infrastructure is needed, which enables masscustomization and responsiveness to market changes. In thecase of repair, remanufacturing of components could be highlyadvantageous both from cost as well as lead time perspectives.5.3 Design Limitations:5.3.1 Over
44、viewIt is useful to point out design character-istics that indicate situations when AM should probably not beused. Stated concisely, if a part can be fabricated economicallyusing a conventional manufacturing process and can meetrequirements, then it is not likely to be a good candidate forAM. The de
45、signer should balance cost, value delivered andrisks when deciding whether to pursue AM.FIG. 3 Parameters for the AM process selectionISO/ASTM 52910:2018(E)5 ISO/ASTM International 2018 All rights reserved5.3.2 A primary advantage of AM processes is their flex-ibility in fabricating a variety of par
46、t shapes, complex andcustomized shapes, and possibly complex material distribu-tions. If one desires mass production of simple part shapes inlarge production volumes, then AM is not likely to be suitablewithout significant improvements in fabrication time and cost.5.3.3 A designer shall be aware of
47、the material choicesavailable, the variety and quality of feedstocks, and how thematerials mechanical and other physical properties vary fromthose used in other manufacturing processes. Materials in AMhave different characteristics and properties because they areprocessed differently that in convent
48、ional manufacturing pro-cesses. Designers should be aware that the properties of AMcomponents are highly sensitive to process parameters and thatprocess variability is a significant issue that can constrainfreedom of design. Additionally, designers should understandthe anisotropies that are often pr
49、esent in AM processedmaterials. In some processes, properties in the build plane (X,Y directions) are different than in the build direction (Z axis).With some metals, mechanical properties better than wroughtcan be achieved. However, typically fatigue and impactstrength properties are not as good in AM processed parts intheir as-built state as in conventionally processed materials.5.3.4 All AM machines discretize part geometry prior tofabricating a part. The discretization can take several forms.For example, most AM machines fabricate
