Patrick Pradel

Investigation of design for additive manufacturing in professional design practice

ABSTRACT Additive Manufacturing (AM) technologies are widely adopted in design practice for prototyping. However, the extent to which practitioners are knowledgeable and experienced in designing components for series production using AM remains poorly understood. This study presents the results of an online survey aimed at uncovering this emerging design activity, with additional evidence provided by semi-structured interviews with 18 designers. One hundred ten practising designers responded. The majority of the respondents remain sceptical about the potential for AM as a process for series production, citing cost and technical capabilities as key barriers. Only 23 reported experience in designing components for series production using AM, with the majority of these designing parts to be produced from plastic. The survey revealed that these designers have developed their own ‘design rules’ based primarily on personal experience. These rules, however, tended to focus on ensuring ‘printability’ and did not provide support for taking advantage of the unique capabilities of AM processes. The designers tended to treat AM processes as a uniform set of production processes, and so the design rules they used were generic and not directed to the capabilities of specific AM processes.

Exploring the Impact of Shape Complexity on Build Time for Material Extrusion and Material Jetting

“Complexity for free” has often been claimed as one of the main opportunities of additive manufacturing (AM). Many examples have proven how, for highly complex and intricate geometries, additive manufacturing is the only available route. However, the implications that shape complexity has on part cost have not been thoroughly explored. This is especially relevant for series production where optimisation of building time can lead to significant cost savings. This study explores how shape complexity impacts build time in Material Extrusion (ME) and Material Jetting (MJ). A screening experiment is presented where the impact of ‘area’, ‘size’ and ‘increase in perimeter’ on build time is analysed. The results show that these three factors influence building time in ME, while only ‘size’ has a significant effect in MJ. Our results challenge the mainstream assumption that all AM processes provide “Complexity for free” while presenting preliminary indications on how to design efficient components for ME and MJ.

A framework for mapping design for additive manufacturing knowledge for industrial and product design

Abstract Design for Additive Manufacturing (DfAM) is a growing field of enquiry. Over the past few years, the scientific community has begun to explore this topic to provide a basis for supporting professional design practice. However, current knowledge is still largely fragmented, difficult to access and inconsistent in language and presentation. This paper seeks to collate and organise this dispersed but growing body of knowledge, using a single and coherent conceptual framework. The framework is based on a generic design process model and consists of five parts: Conceptual design, Embodiment design, Detail design and Process planning and Process selection. 81 articles on DfAM are mapped onto the framework to provide, for the first time, a clear summary of the state of the art across the whole design process. Nine directions for the future of DfAM research are then proposed.

Interplay of Sketches and Mental Imagery in the Design Ideation Stage of Novice Designers

Abstract This paper seeks to understand the interplay between the acts of pen-and-paper-based sketching and the use of mental imagery. A protocol study of four novice designers was conducted in two different environments: with access to sketches only; and blindfolded and delayed sketches. In total there were eight 45 minute design sessions. This study confirms that sketches and mental imagery support ideation stages in unique ways and both are equally germane. Identified interplaying roles when only sketches are utilized are: supporting, co-evolving, and reflecting roles. In addition, interplay can happen at the exact moment or distantly; and the order of an interplay depends on the designers’ strategy. In sessions where sketches are for externalizing design proposals only at the end, identified roles are: generative and provocative to idea exploration. It is also observed that gesture does not compensate for the absence of external representation, although it conveys important design messages.

DESIGNING END USE COMPONENTS FOR ADDITIVE MANUFACTURING Exploring experiences, knowledge and information requirements

The primary aim of this study was to develop an understanding of the experience, the current knowledge regarding the design of end-user components for series production in additive manufacturing (AM) and the information needs of designers involved in designing end-user components for AM. To achieve this, the survey intended to uncover the following aspects of the topic: 1. If and how frequently AM technologies are used by designers for series production of end-user components 2. To what extend designers have had experience of designing end-user components for AM 3. Which aspects are important when designing end-user components for additive 4. Why designers have or not have designed end-user components for series production in AM 5. How designers have learned how to design for AM and which resources they have used 6. What designers would like to know about Design for AM 7. How they prefer this information to be conveyed

Designing end use components for additive manufacturing: navigating an emerging field

Despite much excitement, research and development, Additive Manufacturing (AM) as a series production process for end-use components and products is not yet widespread or considered mainstream. However, there is a clear potential for AM to form a viable alternative to many conventional manufacturing processes, especially in low to medium production volumes. A key enabler for this transformation is the capacity to design components and products that are both able to exploit AM capabilities and avoid its limitations. In recent years, many studies have explored the topic of Design for Additive Manufacturing (DfAM). This report presents an overview of the state of the art of this research area. A systematic review has been carried out to identify the most significant academic studies on the topic. The review resulted in 66 key resources being identified and critically reviewed. These resources have been reviewed and categorised using a generic model of the design process. This categorisation provides and easy and immediate way to map and navigate this emerging field. Consequently, five major research areas are presented: 1. Process planning 2. Detail design 3. Embodiment design 4. Conceptual design 5. Design processes In the discussion, these research areas are examined with the aim of highlighting shortcomings and providing future research directions.

Differences in Sketches and Mental Imagery in Ideation Stage of Novice Designers

Previous empirical studies in sketches and mental imagery showed that there is no significant difference in overall quality and possibility to use mental imagery as design tool. This preliminary study explores distinctions between two kinds of sessions in terms of how ideas are generated. Four design sessions of two novice designers are used to unveil differences. Based on preliminary results, physical properties of sketches underlie differences, also the availability of visual cues apart from the drawings itself. During interpretation stage, sketches provides an additional dialogue which is not available in mental imagery session. The use of mental imagery as design tool in novice designers vary and may not as effective as in experts. Pauses and gesture in both sessions are found to be fundamental designing aspects, including in environment when sketches are allowed. When crucial differences are no longer assumed, interplaying roles between the two can then be explored further.

Multidisciplinary Design Behaviour Using Sketching and Mental Imagery: A Literature Review and Considerations for Future Research

The main behavioural characteristics of the early design stage are that designers move freely between various levels of detail and different cognitive strategies; this is the central tenet of this research. The interplay between the role of sketching and mental imagery during the design process is somewhat mysterious. It is assumed, but not known, how externalisation assists the imagery process and vice versa. In an attempt to demystify this interplay, this paper examines observable behaviour associated with the act of sketching and using mental imagery. It reviews established protocol analytical methods based on two criteria: cognitive strategies and ability to be applied in different design domains. Also, it evaluates the appropriacy of seminal coding schemes for the analysis of mental imagery to better understand moments of insight (idea generation). It concludes that established coding schemes are inadequate methods when used to facilitate analysis of cognitive strategies.