1、ISO/ASTM 52910:2017(E)Standard Guidelines forDesign for Additive Manufacturing1This 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 revision.1. Scope1.
2、1 This document gives guidelines and best practices forusing additive manufacturing (AM) in product 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. These guidelines help determinewhich design c
3、onsiderations can be utilized in a design projector that can be utilized to take advantage of the capabilities ofan AM process.1.3 General guidance and identification of issues aresupported, but specific design solutions and process-specific ormaterial-specific data are not supported. The intended a
4、udiencecomprises three types of users:1.3.1 designers who are designing products to be fabricatedin an AM system and their managers,1.3.2 students who are learning mechanical design andcomputer-aided design,1.3.3 developers of AM design guidelines and design guid-ance systems.1.4 The values stated i
5、n SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 This 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 hea
6、lth practices and determine the applica-bility of regulatory limitations prior to use.2. Normative references2.1 There are no normative references in this document.2,33. TerminologyAdditive manufacturing processes3.1 Definitions: For the purposes of this document, theterms and definitions given in A
7、STM F2792-10, for definitionsof AM processes and concepts, and ASTM F2921-11, forcoordinate systems and test methodologies, and the followingapply.43.1.1 binder jettingAM process in which a liquid bondingagent is selectively deposited to join powder materials.3.1.2 directed energy depositionAM proce
8、ss in whichfocused thermal energy is used to fuse materials by melting asthey are being deposited.3.1.3 material extrusionAM process in which material isselectively dispensed through a nozzle or orifice.3.1.4 material jettingAM process in which droplets ofbuild material are selectively deposited.3.1
9、.5 powder bed fusionAM process in which thermalenergy selectively fuses regions of a powder bed.3.1.6 sheet laminationAM process in which sheets ofmaterial are bonded to form an object.3.1.7 vat photopolymerizationAM process in which liquidphotopolymer in a vat is selectively cured by light-activate
10、dpolymerization.3.2 Other definitions:3.2.1 design considerationtopic that may influence deci-sions made by a part designer.3.2.1.1 DiscussionThe designer determines to what extentthe topic may affect the part being designed and takes appro-priate action.3.2.2 process chainsequence of manufacturing
11、processesthat is necessary for the part to achieve all of its desiredproperties.4. Summary of purpose4.1 This document provides guidelines for designing partsand products to be produced by AM processes. Conditions ofthe part or product that favor AM are highlighted. Similarly,1This test method is un
12、der the jurisdiction ofASTM Committee F42 on AdditiveManufacturing Technologies and is the direct responsibility of SubcommitteeF42.04 on Design.Current edition approved Jan. 8, 2017. Published March 2017. DOI: 10.1520/ISO_ASTM59210-17.2None of the referenced documents are cited as requirements of t
13、he document.3For referenced ASTM standards, visit the 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.4ISO and IEC maintain terminological databases fo
14、r use in standardization at thefollowing addresses: IEC Electropedia: available at http:/www.electropedia.org/,and ISO Online browsing platform: available at http:/www.iso.org/obp. ISO/ASTM International 2017 All rights reservedThis international standard was developed in accordance with internation
15、ally 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.1conditions that favor conventional manufacturing proce
16、sses arealso 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 comprises the main content of theseguidelines (Clause 6), and4.1.3 warn
17、ings 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 mechanicalparts for structural applications, where cost is the pri
18、marydecision 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 designer should alsoconsider risks associated with the selection of
19、 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 decision criteria focus onmaterial availability, whether or not
20、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 mechanical engineeringapplications for technical parts, but are n
21、ot 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 process combination can beidentified, then consideration of othe
22、r design requirements canproceed, including surface considerations and geometry, staticphysical, and dynamic physical properties, among others.These figures are meant to be illustrative of typical practice formany types of mechanical parts, but should not be interpretedas prescribing necessary pract
23、ice.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 general rule, if a part can be fabricated economicallyusing a
24、 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 properties or characteristics, or some combination ofthese charact
25、eristics. 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 AM fabricates parts by adding material in a layer-by-layer manner. Du
26、e to the nature of AM processes, AM hasmany more degrees of freedom than other manufacturingprocesses. For example, a part may be composed of millions ofdroplets if fabricated in a material jetting process. Discretecontrol over millions of operations at micro to nano scales isboth an opportunity and
27、 a challenge. Unprecedented levels ofinterdependence are evident among considerations and manu-facturing process variables, which distinguishes AM fromconventional manufacturing processes. Capabilities to takeadvantage of design opportunities can be limited by thecomplexities of process planning.FIG
28、. 1 Overall Strategy for Design for AMISO/ASTM 52910:2017(E)2 ISO/ASTM International 2017 All rights reserved5.2.2 The layer-based, additive nature means that virtuallyany part shapes can be fabricated without hard tooling, such asmolds, dies, or fixtures. Geometries that are customized toindividual
29、s (customers or patients) can be economically fabri-cated. Very sophisticated geometric constructions are possibleusing cellular structures (honeycombs, lattices, foams) or moregeneral structures. Often, multiple parts that were convention-ally manufactured can be replaced with a single part, or sma
30、llernumber of parts, that is geometrically more complex than theparts being replaced. This can lead to the development of partsthat are lighter and perform better than the assemblies theyreplace. Furthermore, such part count reduction (called partconsolidation) has numerous benefits for downstream a
31、ctivi-ties. Assembly time, repair time, shop floor complexity, re-placement part inventory, and tooling can be reduced, leadingto cost savings throughout the life of the product.An additionalconsideration is that geometrically complex medical modelscan be fabricated easily from medical image data.5.
32、2.3 In many AM processes, material compositions 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 effectivemechanica
33、l properties are desired to vary throughout 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 specifi
34、cFIG. 2 Procedure for identification of AM potentialFIG. 3 AM process selection strategyISO/ASTM 52910:2017(E)3 ISO/ASTM International 2017 All rights reservedprocess and machine. Across the range of AM processes, someprocesses enable point-by-point material variation control,some provide discrete c
35、ontrol 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 composition can be varied invirtually a continuous manner, droplet-to-droplet or even bymixing droplets. Si
36、milarly, the directed energy depositionprocess can produce variable material compositions by varyingthe powder composition that is injected into the melt pool.Discrete control of material composition can be achieved inmaterial extrusion processes by using multiple depositionheads, as one example. Po
37、wder bed fusion (PBF) processes canhave limitations since difficulties may arise in separatingunmelted mixed powders. It is important to note that specificmachine capabilities will change and evolve over time, but thetrend is toward much more material composition flexibility andproperty control capa
38、bility.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 functions can be defined mathematically, the partcan be optimized to achieve those functions. No
39、vel topologyand shape optimization methods have been developed in thisregard. Resulting designs may have very complex geometricconstructions, utilizing honeycomb, lattice, or foam internalstructures, may have complex material compositions andvariations, or may have a combination of both. Research is
40、needed 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 short. Little investment inpart-specific infrastructure is needed, which enables masscustomiz
41、ation 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 Limitations:5.3.1 OverviewIt is also useful to point out design char-acteristics that indicate situations when AM should pr
42、obablynot be used. Stated concisely, if a part can be fabricatedeconomically using a conventional manufacturing process andcan meet requirements, then it is not likely to be a goodcandidate for AM. The designer should balance cost, valuedelivered, and risks when deciding whether to pursue AM.5.3.2 A
43、 primary advantage of AM processes is their flex-ibility in fabricating a variety of part 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 s
44、ignificant improvements in fabrication time and cost.5.3.3 A designer must be aware of 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 AMwill have di
45、fferent characteristics and properties because theyare processed differently that in conventional manufacturingprocesses. Designers should be aware that the properties ofAMcomponents are highly sensitive to process parameters and thatprocess variability is a significant issue that may constrainfreed
46、om of design. Additionally, designers should understandthe anisotropies that are often present in AM processedmaterials. In some processes, properties in the build plane (X,Y directions) will be different than in the build direction (Zaxis). With some metals, mechanical properties better thanwrought
47、 can be achieved. However, typically fatigue andimpact strength properties are not as good in AM processedparts in their as-built state as in conventionally processedmaterials.5.3.4 All AM machines discretize part geometry prior tofabricating a part. The discretization can take several forms.For exa
48、mple, most AM machines fabricate parts in a layer-by-layer manner. In material and binder jetting, discrete dropletsof material are deposited. In other processes, discrete vectorstrokes (e.g., of a laser) are used to process material. Due to thediscretization of part geometry, external part surfaces
49、 are oftennot smooth since the divisions between layers are evident. Inother cases, parts may have small internal voids.5.3.5 Geometry discretization has several other effects.Small features can be ill-formed. Thin walls or struts that areslanted, relative to the build direction, may be thicker thandesired. Also, if the wall or strut is nearly horizontal, the wallor strut may be very weak since relatively little overlap mayoccur between successive layers. Similarly, small negativefeatures such as holes may suffer the opposite affect, becomingsmaller than desired and
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