Design for Additive Manufacturing

SECTION 2: Hazards identification

A specific type of certification, which relates to the Rules of the relevant

2.1 Classification of the substance or mixture

Society Component A part or member of some equipment or a system Conformity Where a design, product, process or service demonstrates compliance with defined specific requirements Design All relevant plans, documents, calculations described in the performance, installation and manufacturing of a product Defect One or more flaws whose aggregate size, shape, orientation, location or properties do not meet specified acceptance criteria and are rejectable. Design analysis Investigative methodology selectively used to assess the design Design review and Part of the appraisal process to evaluate specific aspects of the design No. approval including drawing or solid model review and approval supported by the 186 xx Green part final material specification A green part is a body that is made of powdered material that has been (cont.) (cont) compressed and is held together with a binding material Equivalent An acceptable, no less effective alternative to the specified criteria Essential Any parameter is considered to be essential when any aspect falling Parameters outside the qualified range affects the mechanical properties or final part quality. Essential parameters are to be defined in the specification and are required to be reviewed and surveyed. Any change of essential parameters outside the qualified range requires requalification. Infiltration A process of filling the pores of an un-sintered or sintered object with a metal or alloy of lower melting point than that of the object Installation The assembling and final placement of components, equipment and subsystems to permit operation of the system Manufacturer The party responsible for the manufacturing and quality of the product Manufacturing Systematic series of actions directed towards manufacturing a product process Manufacturing Approval of the process whereby a manufacturer produces a part using process approval additive manufacturing Modification A limited change that does not affect the current approval Part, specific A specific part or component with the same geometric requirements, material requirements and function requirements. Part, family A family of parts (or similar parts) with the same function requirements, material requirements and same design features or shape but different size or section thickness. Part, similar A similar part with similar function requirements, the same material requirements and similar design features including different shape, size, thickness. NDT indication A response from a reflector during an NDT test that can further be classified as relevant or non-relevant, and usually requires further evaluation to determine its acceptability against the specified acceptance criteria. Performance test A technical operation where a specific performance characteristic is determined Prototype test Investigations on the first or one of the first new parts for optimization, fine tuning of equipment/system parameters and verification of the expected running behavior Qualified or The granting of permission for a design, product, service or process to Qualification be used for a stated purpose under specific conditions based upon a satisfactory appraisal by the manufacturer Repair Restore to original or near original condition from the results of wear and tear or damage for a product or system in service Reverse A process to disassemble and examine or analyze in detail (a product Engineering or device) to discover the concepts involved in manufacture, usually to produce something similar (a product or device). i.e. AM building a new product by scanning an existing product. Consideration of intellectual property (IP) issues should be addressed on a case-by-case basis. Sintering A thermal treatment of a powder or compact, at a temperature below the melting point of the main constituent, for the purpose of increasing its strength by the metallurgical bonding of its particles Specification Technical data or particulars which are used to establish the suitability No. of materials, products, components or systems for their intended use. 186 xx The specification could be provided by the manufacturer or purchaser and should be agreed by the purchaser (cont.) (cont) Witness An individual physically present at a test and being able to record and give evidence about its outcome. Remotely present may be specially agreed by each Class Society. 3. Design Requirements 3.1. General The quality and performance of the AM part should be considered for part design requirements and the material requirements, with appropriate control of essential parameters during the manufacturing process including pre-build, build and post-build. The additive manufacturer should prepare a product design package, refer to Table 3, including additive manufacturing procedures, specifications in accordance with the purchase specification, the purchase order including all the requirements for the fabrication of all built parts, etc. Table 3 Product Design Package No. Item Design Code, Rules, Standards, or Manufacturer/OEM’s Specifications AM Level (1, 2 or 3) Revision controlled drawing, CAD model or digital build file including test coupons (for reference) The applicable material specification with acceptance criteria for each intended part/application Design analysis report, if applicable Powder/wire/binder specification AM pre-build, build and post-build specification/procedure Inspection and Testing Plan Any other specifications, requirements or procedures identified as necessary by the additive manufacturer or purchaser. Part solid model/drawing and materials specifications should be qualified in accordance with Section 6 and included in the qualification records in accordance with the applicable subsection 3.2 and 3.3 The qualified specifications and procedures for the AM part should be followed and retained in the additive manufacturer’s production records. 3.2. Drawing or Solid Model Part design includes the creation of the part drawing or solid model for end-use and should consider the achievable material properties defined in the final material specification. The CAD model or drawing for the final AM part should include requirements for final geometry, dimensions, and tolerances in accordance with an internationally recognized industry standard, e.g. ASME Y14.46 2018, Y14.41 2019, Y14.5 2018 If the CAD model or drawing for the final AM part is redesigned, optimized by topology, or generated by design algorithms, the CAD model for the final AM part should be calculated or simulated using engineering software to verify design compliance and integrity for service. The No. design analysis report including the applicable procedure and results should be submitted for 186 xx review by the Class Society for Level 3. (cont.) (cont) The optimized design requirements for the final AM part should demonstrate at least an equivalent level of functionality and integrity, such as the capability to withstand the applied loads or the applied environmental conditions to traditionally manufactured parts, which the Class Society should accept and approve for Level 3, and could accept and approve for Levels 1 and 2. The revision number of the solid model, drawing or digital build file should be included in the AM part approval and included in manufacturer’s production records. 3.3 Material Specification Refer to Table 4, the material specification should include all material properties, including the specified AM process, for the final delivered condition and the acceptance criteria for the AM part or material. The selected material specification/grade with the heat treatment condition should be identified in the final AM material specification. Depending on the intended application, the acceptable material properties should provide equivalency to traditional manufactured materials in accordance with applicable IACS UR W, Rec., or alternatively with internationally recognized industry standards or the designer’s specifications. Due to the inherent morphology of the AM process, consideration may be given to use an AM material with alternative chemistry and enhanced mechanical/corrosion properties, which are equivalent to or exceed the material properties typically required in the service condition, such as impact, fatigue, wear, or corrosion resistance. The selected final AM material should be appropriate for the loading condition, the functionality, the environment, and should be approved by the Class Society as an alternative new manufacturing method for the specified part/application. The following items in Table 4 should be specified in the AM material specification for the final delivered condition. In the case of AM materials for AM Level 3, the material specification, including the following items in Table 4, should be submitted to the Class Society for approval. Table 4 Final Material Specification No. Item Material type and grade Manufacturing process, including the AM process and any post-build heat treatment process Chemical composition 4 Microstructure, such as grain size, and metallographic analysis 5 Fusion density, applicable to powder processes and not required for wire DED 6 Tensile properties 7 Charpy impact properties and test temperature, if required, according to the design temperature and material grade 8 Hardness tests, if required 9 Other special properties such as fatigue, fracture mechanics properties, corrosion, erosion, or wear resistance, if required for the intended application 10 Non-destructive testing methods, test level, quality level, and acceptance criteria Notes: 1. Microstructure, fusion density and special properties are required during No. qualification/approval but are optional for production. 186 xx 4. Feedstock Specification (cont.) (cont) 4.1. General The feedstock supplier should maintain a quality management system, which should, at least, meet the minimum requirements in accordance with internationally recognized quality standards such as ISO 9001:2015. Feedstock material should be qualified using feedstock materials approval tests in accordance with Annex 1, referred to in subsection 1.6 v). If approval is already granted by other Classification Societies, evidence of the approval together with documentation of performed approval tests should be submitted. The indicated approval tests in Annex 1 could be reduced with the agreement of the Class Society. 4.2. Powder Feedstock 4.2.1 Powder Feedstock Specification For powder feedstock material specification, documentation, handling, and storage, internationally recognized industry standards, such as ISO 17296-2:2015, ISO/ASTM 52907:2019, can be referred to by the manufacturer. Refer to Table 5, the powder specification should be defined with the applicable powder manufacturing process and the range of essential parameters. Refer to Table 6, the non- essential parameters should be indicated for information. Unless otherwise agreed the powder specification could be qualified for certified items by the manufacturer and should be approved for class items by the Class Society, to a range of parameters, refer to Annex 1. Any change of essential parameters outside the qualified range requires requalification. The essential parameters for powder feedstock include the following items in Table 5: Table 5 Essential Parameters for Powder Feedstock No. Essential parameters for powder feedstock 1 Material grade 2 Powder manufacturing process, including the melting and atomization process, type of gas used, environmental conditions. 3 Post-atomization process, such as sieving. 4 Chemical composition 5 Powder size range 6 Particle size distribution 7 Powder morphology and internal microstructure 8 Flowability 9 The applicable additive manufacturing process (e.g., powder for PBF-LB, powder for PBF-EB, powder for DED, or powder for BJT) Non-essential parameters for powder feedstock include the following items in Table 6: Table 6 Non-essential Parameters for Powder Feedstock No. Non-essential parameters for powder feedstock 186 xx 2 Thermal properties, such as solidus, liquidus temperature for reference 1 Density, such as apparent density, tap density, skeletal density, and fusion density (cont.) (cont) 3 Oxygen content 4 Moisture content, etc. The manufacturer should ensure that feedstock materials comply with all local and national regulations for environment, handling and safety. 4.2.2 Powder Feedstock Documentation The powder supplier should issue a statement of conformity in accordance with the additive manufacturer’s powder feedstock specification. For each powder lot and/or batch supplied, the powder supplier shall document, for raw material control and traceability, the information given in Table 7: Table 7 Documentation for Powder Feedstock No. Item 1 Procurement information (Powder should be sourced from a feedstock supplier approved by the Class Society for class items.) 2 Powder supplier’s contact information 3 Lot and Batch Number 4 Powder description 5 Powder manufacturing process, including the melting and atomization process, type of gas used, environmental conditions 6 Post-atomization process, such as sieving 7 Sampling methods such as chute splitting, blending or spin riffling 8 Testing method, standard, and results required by the powder material specification 9 Packing date, quantity, handling requirements, shelf life and storage instructions 10 SDS Notes: 1. The control of powder feedstock is by Lot Number and Batch Number. Powder from the single Lot Number and single Batch Number indicates that quantity of feedstock produced under traceable and controlled conditions from a single manufacturing process cycle. The size of the feedstock lot is determined by the feedstock supplier. A single powder lot is used as feedstock in build cycles. Powder from the single Lot Number and multiple Batch Number indicates that quantity of feedstock produced under traceable and controlled conditions from a single manufacturing process cycle. The remaining feedstock of insufficient quantity to complete the build cycle that has been used in multiple AM machines is combined, blended and used to finish the powder lot. Powder from multiple Lot Numbers indicates that more than one powder lot is used as feedstock in build cycles. Multiple lots are usually blended before being loaded into the feed region. 2. Samples taken for testing should be representative of the powder lot, ensuring homogeneity when split. ASTM B215 can be referred to for sampling of metallic powders subject to a prior customer/supplier agreement. The sampling method(s) should be reported. For sampling metal powder, the preferred method is to use a dynamic sampling technique like chute splitting or spin riffling to ensure a representative sample is collected by dividing the powder stream while it is flowing, minimizing segregation issues that can occur with static sampling methods. 4.2.3 Powder Recycling No. 186 xx Powder should be protected against damage, contamination, and deterioration during handling, storage, and recycling. (cont.) (cont) For the DED powder process, only powder which has not exited the DED nozzle may be recycled. For the PBF or applicable BJT processes, powder recycling with mixed lots is not allowed. Powder recycling for the same lot may be allowed in accordance with procedures agreed by the Class Society. Procedures for powder recycling may consider the following factors in Table 8: Table 8 Factors for Powder Recycling No. Factors 1 The documented methods for tracking the progression of powder recycling 2 Limitation for powder recycling times 3 Performance of the final delivered material property by the recycled powder 4 The documented control procedures, such as sieving, blending, testing oxygen, moisture, or other practices 5 Test results of the essential parameters should be within the specified range of virgin powder, if applied 6 Implementation of procedures for prevention of cross contamination on multi- materials use by one machine. Alternatively, linking one machine for one type of material 4.3. Wire Feedstock 4.3.1 Wire Feedstock Specification For wire feedstock, internationally recognized industry standards such as AWS A5.01:2019, AWS A5.32 2021, ASME BPVC. II. C 2023 or other equivalent standards such as ISO 14175:2008 can be referred to by the manufacturer. The wire specification should be defined including the manufacturing process and the acceptable range for the essential parameters in Table 9. Any non-essential parameters should be indicated for information in the procedure qualification record specified in subsection 5.5. Unless otherwise agreed, the wire specification should be qualified for certified items by the manufacturer or approved for class items by the Class Society. Qualification should include the acceptable range for the parameters. Any change of the following essential parameters outside the qualified range requires requalification. Table 9 Essential Parameters for Wire Feedstock No. Essential parameters 1 Material grade 2 Mechanical properties 3 Chemical composition 4 Wire size 5 Tolerance and surface condition (Ra) throughout the length 6 The applicable additive manufacturing process for which the wire feedstock can be used 4.3.2 Wire Feedstock Documentation No. 186 xx The wire material supplier should issue a statement of conformity and document the following information in Table 10 for raw material control and traceability per lot per batch. (cont.) (cont) Table 10 Documentation for Wire Feedstock No. Information 1 Wire should be sourced from a feedstock supplier approved by the Class Society for class items. 2 Wire supplier’s contact information 3 Lot and Batch Number 4 Wire description such as wire size, material grade, AWS designation, F No., A No. if applicable 5 Wire manufacturing process 6 Associated shielding gas 7 Testing method and results as required by the wire specification 8 Packing date, quantity, and instructions for handling, storage, incoming control 9 As-built properties and Post Weld Heat Treatment (PWHT) properties, if applicable 10 SDS 4.4. Binder Feedstock If required, the binder feedstock specification should be qualified by the AM facility. The following factors in Table 11 should be specified or considered by the manufacturer. Table 11 Factors for Binder Feedstock No. Factors 1 Material grade 2 Chemical composition 3 Viscosity 4 Surface tension 5 Thermogravimetric analysis 6 Flash point 7 Evaporation temperature 8 Curing temperature 9 Storage, handling, and expiration date, if applicable Notes: 1. Additional factors which should be considered during binder selection include: deposition method, compatibility with building process, interaction between binder and powder, effects on the strength of the as-built part, stability, and burnout characteristics. The binder feedstock is a secondary material, which is a liquid bonding agent or glue that binds the metal/ceramic particles together. The binder feedstock can affect the binder jetting and sintering/infiltration process but should not affect the quality of the final part. The final material properties and part dimensions should be achieved by the post-build sintering/infiltration process. The qualification of binder materials should be documented by the AM facility and submitted to the Class Society, if deemed necessary. 5 Additive Manufacturing Procedure Specification (AMPS) No. 186 xx 5.1. General (cont.) (cont) The AMPS should be documented by the additive manufacturer for controlling and monitoring both the essential parameters and non-essential parameters that may affect the final part quality. The AMPS should be qualified using a range of parameters in association with the approval tests by the Class Society. Any change of essential parameters beyond the range should be requalified. Test witnessing is required for class items and certified critical items. The applicable essential and non-essential parameters should be documented by the AM facilities/manufacturers. Any parameter that influences heat source/input and heat deposition/history should be considered as an essential parameter. The additive manufacturing procedure should be included in the additive manufacturer’s production records. 5.2. Pre-Build Procedure The following pre-build process characteristics in Table 12 should be defined and identified, which may be supported by slicing software for the preparation of the manufacturing procedure: Table 12 Pre-build Process Characteristics No. Pre-build process characteristics 1 Part location and orientation 2 Test coupon location and orientation 3 Machining allowance for part and test coupon, if applicable 4 Build location and nesting, if applicable 5 Build surface, direction, and gravity direction, if applicable 6 Support/infill structure, if applicable 7 Appropriate cleaning procedure for build platform Notes: 1. Part orientation should be identified relative to a specified build surface, such as the build platform or incorporated substrate. If applicable or required, the build location should be identified using X, Y, Z directions in accordance with internationally recognized industry standards, such as ISO 17295:2023. 2. For PBF or applicable BJT processes, the part may be oriented and optimized using pre-build software, to reduce the build time or thermal residual stress. For PBF processes, the location of a single part may be specified within a build envelope. Multiple build locations may be necessary when multiple parts are built simultaneously within the same building envelope. 3. For DED processes, parts may be oriented vertically, horizontally or to other angles determined by machine flexibility to manipulate the substrate. 4. Test coupons should be identified in the build layout with a unique label. If the build layout and build surface are depicted, the build location, orientation, and related tolerance for test coupons are also to be indicated in accordance with internationally recognized industry standards such as ISO 17295:2023. Digital build models of parts and test coupons should be submitted for reference as part of the submission. 5. For PBF or applicable BJT processes, test coupons may be built as near-net-shape test samples or test samples could be retrieved from the sufficient test blocks. 6. For DED processes, test coupons may be taken from a prolongated part/artifact, or a No. separate test block that represents the part features or part section thickness, which 186 xx 7. For PBF or applicable BJT processes, overhangs and sacrificial support structures may can be specially considered and agreed to by the Class Society. (cont.) (cont) be applied for support during fabrication, if required. Alternatively, the part may be re- orientated during the building process to avoid overhang if this is possible. If specified, a bounded surface or volume region may be used to define locations to limit or require support/infill structure. If not specified, a default support/infill structure may be applied depending upon the machine and software. Internationally recognized industry standards, such as ISO/ASTM 52950:2021, may be referred to for an overview of data processing. Digital files may include derivatives from the original CAD model (e.g., STL, AMF, STEP or 3MF). Digital build files should be accurately exported, especially for the critical features, documented and submitted for information, if deemed necessary by the Class Society. During exporting digital building files, the conversion of digital building file from solid model to machine recognized model/code should be verified and any errors should be fixed automatically by available software or manually by the operator. 5.3. Build Procedure 5.3.1 General Building parameters related to heat source/input, refer to subsection 5.3.2 for PBF processes and 5.3.3 for DED processes, and heat deposition/history, refer to subsection 5.3.2 for PBF processes and 5.3.3 for DED processes, are considered as essential parameters and should be specified in the procedure specification, controlled, and qualified within the range. Non-essential operating parameters identified by experience or fixed parameters imposed by the machine system should be documented and controlled as much as possible, including the build platform, build environment, and any other related parameters. If process characteristics are required for in-process monitoring during building, those requirements should be monitored for conformance, such as machine building errors, failures, or defect inspection. 5.3.2 Powder Bed Fusion (PBF) For powder processes, internationally recognized industry standards, such as ISO/ASTM 52904:2019, can be referred to by the manufacturer for inclusion in the procedure specification. PBF-EB has similar capabilities as PBF-LB but demonstrates differences due to different beam sources. Compared with PBF-LB, the beam energy transferred by the electron beam is higher. The process may operate at higher temperatures, with faster build rates and relatively lower resolutions. Additionally, the powder bed is preheated to slightly below melting temperature, which results in less thermally induced stress. The parameters in Table 13 should be defined in the PBF-LB or PBF-EB procedure specification. Table 13 Additive Manufacturing Procedure Specification for PBF Process No. Item 186 xx a. Beam type, such as laser or electron beam 1 Heat Source: (cont.) (cont) b. Beam power c. Beam size d. Beam frequency or waveform control e. Beam splitting f. Beam focus setting 2 Deposition: a. Layer thickness b. Scan pattern/strategy c. Travel speed d. Hatch overlap, distance/spacing e. Specific settings control for edges or surfaces 3 Build Environment for PBF-LB: a. Build platform material specification/designation, thickness, surface finish, dimension, parallelism, and tolerance b. Build platform preheat temperature c. Shielding gas composition and flow rate d. Supplemental gas shielding e. Build chamber gas composition f. Environmental enclosure hardware and configuration 4 Build Environment for PBF-EB: a. Build platform material specification/designation and thickness b. Build platform preheat temperature c. Vacuum pressure d. Build Environment 5 Other Parameters: a. Re-coater blade type, material, or roller wear b. Powder dosing rate c. Ambient environmental conditions d. Feedstock condition, such as powder lot, batch number, virgin or recycled 5.3.3 Directed Energy Deposition (DED) For DED processes, internationally recognized industry standards, such as ASTM F3187:2016, can be referred to by the manufacturer for inclusion in the procedure specification. The parameters in Table 14 should be defined in the DED procedure specification. Table 14 Additive Manufacturing Procedure Specification for DED Process No. Item 1 Heat Source: a. Type of beam/arc b. Beam/arc power c. Beam/arc size d. Heat pulse frequency or waveform control e. Preheating by beam splitting (not applicable to PA-DED, GTA-DED, and GMA- DED) f. Use of energized (pre-heated) wire (not applicable to Powder DED) g. Beam/arc focus setting (not applicable to PA-DED, GTA-DED, and GMA-DED) 2 Deposition: a. Programmed layer thickness (applicable to laser powder DED, not applicable to other DED processes) b. Scan pattern/toolpath No. c. Travel speed 186 xx applicable to other DED processes) d. Hatch overlap, distance/spacing (applicable to laser powder DED, not (cont.) (cont) e. Feed rate f. Start working distance/nozzle standoff distance (not applicable to PA-DED, GTA-DED, and GMA-DED) g. Specific settings that may affect edge and surface build condition h. Wire delivery parameters such as incidence angle, offset distance or path orientation (not applicable to powder DED) i. The applied techniques such as weaving, multi-wires or pulse for wire DED, if applicable j. Start and stop point 3 Build Environment: a. Build platform material specification/designation, thickness, surface finish, dimension, and tolerance b. Build platform preheat temperature c. Inter-pass temperature and inter-pass cleaning, if applicable d. Shielding gas composition and flow rate (not applicable to EB-DED) e. Powder carrier gas flow rate (applicable to powder DED) f. Supplemental gas shielding (not applicable to EB-DED) g. Supply gas composition (not applicable to EB-DED) h. Build chamber gas composition, if applicable i. Vacuum pressure (applicable to EB-DED only) j. Environmental enclosure hardware and configuration 4 Other parameters: a. Orientation of heat source impingement b. Ambient environment conditions, such as temperature, moisture, etc. c. Feedstock type, such as powder or wire Notes: 1. If the substrate is integrated within the final part, the mechanical and metallurgical properties at the bonding interface, together with any inspection requirements, should be included in the qualification tests. The substrate for qualification should be representative of the substrate for production. 5.3.4 Binder Jetting (BJT) The main parameters in Table 15 should be defined in the BJT or equivalent procedure specification. These factors are the AM build parameters, which should be controlled for the dimensions of the green part. The final dimensions and quality are determined by the sintering/infiltration process of the brown part. Table 15 Main Parameters for BJT Process No. Main parameters for BJT 1 Layer thickness 2 Powder spread, if applicable 3 Build speed 4 Binder saturation, if applicable 5 Drying time and heater powder ratio, if applicable 6 Build orientation 7 Travel strategy No. 186 xx (cont.) (cont) Green Part Brown Part Figure 2 Schematic for Binder Jetting Process 5.3.5 In-Process Monitoring or Controlling Some AM systems may have subsystems using one or more real-time sensors to monitor or control various performance and status indications during building, such as melt pool temperature, size, lack of fusion, spattering, and other parameters. If subsystems can change or can control any qualified essential parameters, subsystems should be included in the AMPS and are required in qualification records, including details of the monitoring or controlling type and method, monitoring or controlling system settings and the qualified essential parameters. Subsystems are not required in AMPS and qualification records, if they do not change or do not control any qualified essential parameters. 5.4. Post-Build Procedure 5.4.1 General The post-build process required to meet the quality and properties of the final delivered part should be provided in documented procedures or specifications. The parameters such as temperature, soak time, and cooling media should be specified and controlled by the heat treatment facility. Reference should be made to industry standards depending upon materials. If specified, allowances for machining could be referred to internationally recognized industry standards or manufacturer’s practices. The same post-build heat treatment processes should be applied to the test coupons and the sacrificial/actual parts if the post-build process affects the final delivered material properties or is defined as an essential parameter. 5.4.2 Powder Removal The manufacturer’s procedure should include a process for removal of loose powder from parts manufactured by PBF or BJT processes. The residual powder in the part may cause health and safety issues for personnel while working during the post processing steps, especially for reactive materials such as titanium-based or aluminum-based powder. Any health and safety risks should be identified and either designed out or minimized. 5.4.3 Heat Treatment No. 186 xx Heat treatment, where specified, should be in accordance with Class Rules, internationally recognized industry standards, or best practice suited to the materials, refer to the same (cont.) (cont) traditionally manufactured material grade. To avoid distortion, the part should be adequately supported during heat treatment as appropriate for the component shape/complexity. 5.4.4 Part Removal Procedures should be prepared by the manufacturer for part removal or support structure removal. The following information in Table 16 should be documented: Table 16 Procedure for Part Removal No. Item 1 Suitable build platform temperature when the part is planned to be removed from build chamber 2 If applicable, powder removal needs to be verified before heat treatment 3 Applicable methods and tools, such as band saw, slow speed saw, manual tools, machining, grinding etc. Step-by-step instructions Generally, to reduce residual stress, stress relief heat treatment should be carried out before the part is removed. However, this might not be applicable for large parts due to the furnace capacity. Therefore, there are some cases where parts may be removed before stress relief heat-treatment. Depending upon materials, special attention to avoid cracking may be required and this should be specially considered and agreed to by the Class Society. The removal of support structures should be done in a manner to avoid detrimental impact on the part. This can be proactively considered during design for the ease of removal of the interface between the support structure and the part. 5.4.5 Surface Finish or Machining Surface finishing is important for fatigue, non-destructive testing, maintaining tolerance, surface texture and appearance. Surface finish should be in accordance with the manufacturer’s procedure. Surface finishing or additional machining operations should be performed after the applicable heat treatment processing due to potential deformation and discoloring/oxidization during heat treatment. 5.5. Additive Manufacturing Procedure Specification Qualification Refer to Table 17, the purpose of procedure qualification is to demonstrate the capabilities of an AM procedure to produce a specific AM build component, AM feedstock, AM final material, or repair part by an AM process to meet the requirements. The AM procedure specification (AMPS) should document the required variables to ensure the repeatability of the AM process. Procedure qualification records should document the data recorded during qualification testing, including the applied parameters and corresponding test results. Qualification records for AMPS should be established and documented for review and survey when approval is requested for an AM part, AM feedstock, AM manufacturers for final material, AM repair facilities, refer to Table 17. The qualification procedure of an AM repair facility, as described in Annex 3, requires both a No. procedure specification and documented qualification records. See also subsection 10.4 for 186 xx Repair of an AM Part. (cont.) (cont) Table 17 Additive Manufacturing Procedure Specification Qualification Qualification records for AMPS Item Detail The qualification procedure for an AM part, as described in Section 6, AM Part requires the procedure specification and the documented qualification records for the delivered part and should meet all the design requirements in Section 3. The qualification procedure for AM feedstock, as described in Annex 1, AM Feedstock requires the procedure specification and documented qualification records to meet the requirements for the final delivered feedstock material in subsection 3.3. The qualification procedure for an AM manufacturer for final material, as AM Manufacturer described in Annex 2, requires the procedure specification and documented qualification records for the final delivered material and should meet the acceptance criteria in subsection 3.3. The qualification procedure for an AM repair facility, as described in AM Repair Annex 3, is applicable when using an AM process for repair of in-service damaged parts. The part(s) will require a procedure specification and documented qualification records. 6. Additively Manufactured Prototype Part Qualification