This article introduces you to the TR 70 -2019, Guidelines on the selection criteria for metal additive manufacturing processes which is a Technical Reference published by Singapore Standards council.

Dealing with Metal Additive Manufacturing selection related dilemmas is the second part in the special series AM Standards and Certification – Discussion on the rules of the “gAMe”. The first part examined the the need for standards and how standards adoption can help to boost technology adoption.

When an organization thinks about AM adoption they often confronted with lot of dilemmas related to choice between additive vs conventional manufacturing route, selection of AM materials and process alternatives, design suitability of AM processes etc. 

Sometimes such a dilemma can be resolved by  taking advise from machine makers or suppliers or otherwise by writing down a list of all the benefits and all the costs for each option. But this method could be tedious and often misleading due to lack of domain knowledge. 

However best method to resolve the issue would be by finding out more information from a reliable source such as AM standard or best practice guideline. Through this series of AM standards we would like to introduce you relevant standards to help you in gathering enough information to make an informed decision. Standards are the distilled wisdom of people with expertise in their subject matter they represent.

In this article, I would like introduce you TR 70 -2019,  Guidelines on the selection criteria for metal additive manufacturing processes which is a Technical Reference published by Singapore Standards council. I was an active member of the Technical Committee on Additive Manufacturing that developed this document.  The Singapore Standards Council (SSC), the Ministry of Defence (MINDEF) and the Singapore Armed Forces (SAF) developed TR 70 with key stakeholders including the Defence Science and Technology Agency, Singapore University of Technology and Design, the National Additive Manufacturing Innovation Cluster (NAMIC), the additive manufacturing industry, and the Singapore Manufacturing Federation – Standards Development Organisation.

A Technical Reference (TR) is a pre-Singapore Standard, that is used by the market before a full consensus is reached. It could be about making a product, managing a process, delivering a service or supplying materials etc. Users of the TR are invited to provide feedback on its technical content, clarity and ease of use.

Scope of TR 70 -2019 : 

This is a document with total 41 pages. Among other things TR 70-2019 primarily provides guidelines for process selection between conventional manufacturing (CM) and additive manufacturing (AM) involving metals. It also helps to determine the suitability of AM as a manufacturing process on an existing design or new design. In addition, benefits and limitations of manufacturing processes and factors of process selection are illustrated to support the decision-making of the process

Major topics covered : 

• Comparison between conventional and AM processes
• Advantages and disadvantages of conventional and AM processes
• General framework of process selection
• A selection procedure for material and AM process alternatives
• Comparison of manufacturing processes based on redesign purpose using AM
• Common metal materials for metal PBF-M
• Comparison of CNC machining, metal PBF-M and DED

Other interesting topics :

• Formulation of the selection decision support problem
• Relative importance through the ranking method

• Rating process alternatives with respect to attributes 
• Recommended manufacturing process according to the number of parts
• Cost comparison according to the number of parts

Useful charts : 

• A chart for part and process selections based on design complexity and production volume after design feasibility check
• A chart for process selection based on the relationships between manufacturing cost and design complexity

Highlights of main sections 

• Framework for manufacturing process selection:

Section 6 of TR 70 -2019 provides a general framework to guide the users to decide appropriate manufacturing processes when adopting AM processes.

This framework outlines design benefits of existing and new part design, manufacturing benefits as a viable solution to resolve constraints of CM and economic benefits. The process starts with the consideration of either an existing part design or the opportunity to design a new part or module.

General framework of process selection is illustrated in a flow chart to guide the users through a systematical sequence of various steps such as AM feasibility of design, material selection to rank process alternatives etc. 

• Design suitability for AM process:

Section 7 of TR 70 -2019 provides guidance to users in the form of questions to help them assessing the AM possibility of the design rather than assessing the design in terms of specific manufacturability and economic benefits. A detailed flow chart with a procedure for design suitability check is provided. 

• Selection of AM material and process alternatives

Section 8 of TR 70 -2019 provides can provide a process of material selection for AM through three steps. Users should identify design requirements of a part or definition of application of the part first. Then proceed with other steps. A detailed flow chart with selection procedure for material and AM process alternatives is included in this section. 

• AM process feasibility from the business perspective and AM process selection

Section 9 of TR 70 -2019 provides guidance on business analysis when adopting AM and the final selection of an appropriate AM process and complimented with a detailed flowchart. After the business analysis, users can select an appropriate AM process.

Relevance:

Target users of this TR are AM design engineers, manufacturing engineers, maintenance engineers, industry associations, research institutions and government agencies. However, this document is useful as a reference for AM based digital warehouse architects, AM roadmap developers, AM software developers etc.

Concluding remarks:

TR 70 will guide end users in the evaluation of business and technical feasibility and the selection of additive manufacturing processes to produce a part for its intended application. Through providing clear and comprehensive guidelines on matching suitable processes to specific parts and purposes, This would significantly shorten the time needed in additive manufacturing processes, enabling faster turnaround for the manufacturing of parts.

TR 70 -2019 provides wealth of qualitative information related to topics discussed this document that is very helpful for new AM adopters to expedite their learning curve. Even though, this document only covered few AM processes the methodology suggested may be useful for other AM process that are not included here.  It is a recommended document to refer when relevant. 

Link to document : TR 70 can be purchased from the Singapore Standards eShop at www.singaporestandardseshop.sg.

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