Design for Additive Manufacturing

Based on advances in digital geometry data processing and control technology, stereolithography was the first additive manufacturing process to be patented in 1984 by Chuck Hull. Although additive manufacturing is thus a relatively young discipline, the effects that can be achieved with the various additive technologies in terms of efficient product and manufacturing process optimisation are of outstanding importance.

Considering the complexity of the topic of additive manufacturing and its implications for product development, a methodology must structure and explain the technical as well as the operational process and recommend concrete methods for finding solutions. In this chapter, we will first discuss the structuring of the topic, the technology and the product creation process in general, as well as specific implications for the topic of additive manufacturing. The various aspects that support an engineer in the design process, such as the concrete procedure, heuristics and methods, tools, specifications and the connecting knowledge base, are then provided in the following chapters.

The question of when and with what benefit additive manufacturing processes can be used in an industrial context is not easy to clarify and is often answered with rapid prototyping, small quantities or lightweight design. Occasionally, attempts are also made to convert components designed for classic manufacturing processes to additive manufacturing.

To show that the strengths of the technology, especially in relation to additive “series production”, are much greater and more diverse, and how to recognise and implement them, is to be a major contribution of this book.

To this end, this chapter takes a look at the strengths, weaknesses, opportunities and risks of additive manufacturing, with the aim of supporting the company's own idea generation and planning. Subsequently, methods of assessing the potential in the corporate context are presented and aspects and criteria of suitability in principle are discussed. This is followed by a component portfolio analysis. Finally, an evaluation catalogue for component suitability for additive manufacturing is discussed for this chapter.

In the following chapter, the creative methods of “Design with Additive Manufacturing” are presented. The focus is on the use of the design freedoms and potentials for expanding the design space. To this end, in Sect. 4.1 requirements are specified in the form of a checklist, which must be taken into account in additive manufacturing. Subsequently, the design goals and constructive contradictions are presented in Sect. 4.2. It should be emphasised that by pursuing several design goals in the conceptual design phase, a clear added value can be realised compared to conventionally manufactured products. Based on design goals and contradictions, we address the general functional structure in Sect. 4.3, from which the necessity of effect engineering (Sect. 4.4) emerges. Subsequently, in Sect. 4.5, the product architecture is elaborated and approaches from bionics are presented. Based on this, methods for the embodiment design, such as design principles, the one-piece machine method and methods of structural optimisation, are considered in detail in Sect. 4.6. Finally, in Sect. 4.7 discusses the development environment.

In the following chapter, the restrictive methods of “Design for Additive Manufacturing” are considered. The chapter begins with a section on design guidelines, which must also be taken into account when executing the design in the context of additive manufacturing. In Sect. 5.2, we discuss concrete restrictions for the PBF-LB/M, as an example which have to be taken into account during the detail design phase. Based on this, in Sect. 5.3 we discuss relevant post-processing methods in order to realise the desired part properties. Finally, in Sect. 5.4 we present insights into the cost calculation.

In this chapter, the machine setup for additive manufacturing is addressed. This includes both the available material classes and a comparison of the material properties between conventionally manufactured and additively manufactured parts. To this end, we will highlight the excellent mechanical properties of metallic additively manufactured parts, which even surpass the mechanical properties of cast components. We will then go into the machine parameters and describe how they influence the component properties.

Validation and quality assurance is a central part of the additive manufacturing process chain. Taking into account the numerous process parameters and the comparability with traditional manufacturing methods, it is essential to test and validate the processes and additively manufactured parts. For use as a highly stressed structural component, high porosity, inclusions and blowholes must be excluded and a homogeneous material structure must be realised.

At the top of the process chain is process simulation (Sect. 7.1). On this basis, critical areas of the part, but also thermal distortion, can already be detected. Subsequently, measures for process monitoring and control can be taken in order to detect defects during the build cycle and to derive strategies for action (Sect. 7.2). Following the build cycle, non-destructive testing methods, such as CT scans, should be applied (Sect. 7.3). Finally, it is advisable to validate the product properties on individual parts by destructive testing, if necessary (Sect. 7.4).

In the past ten years we have carried out more than 40 projects on design for additive manufacturing. It can be seen that, in addition to the classic design methods, it is above all the methods described in chapters 3 to 5 are essential for finding solutions, as are the methods of potential identification and specification for additive manufacturing, variation of product structure and shape, bionics and shape optimisation. Design guidelines and concrete restrictions can be taken from data sheets and catalogues and support the focused implementation as well as lessons learned.

Each development takes place in a specific context. The definition of the objective associated with additive manufacturing is crucial for successful design. The design process follows the logic generally described in VDI2221. However, the expression is strongly dependent on the respective design objective and the physical contexts to be handled. Analogies from the following case base can help to develop a solution for one's own challenges.

In the case base, examples are presented for each of the eleven design goals described above.

The following aspects are discussed for each example:

In addition to the pre-, in- and post-processes, additive manufacturing is also embedded in a chain of processes in terms of company type, the structure of which reflects the respective business model. The following sections deal with the idea of these business models/business cases and the resulting process chains as well as the questions about the strengths, weaknesses, opportunities and risks of additive manufacturing in the context of the process chains. Ten typical business cases are outlined as examples. Real mixed forms and further business cases can be found.

In the following, we briefly describe the respective business cases, summarise the process chain and discuss the strengths and weaknesses of the respective business model.

If we take a look at the status of the methodology to support development for additive manufacturing, it is noticeable that many authors deal with the description of the machines and their technology and that there are also numerous sources on design rules and examples.

We would like to conclude with three reflections on this book: