Additive manufacturing (AM), colloquially known as 3D printing, has gained prominence over the last 15 years and has moved out of the laboratory and into the industrial product stream, becoming a viable manufacturing option. It has come to fascinate designers and the public alike due to its unique capabilities when compared to conventional manufacturing. These are, namely: shape, material, hierarchical, and functional complexity. Both novice and experienced designers have the desire to enhance their designs with AM, but they need assistance in learning to take advantage of these new capabilities and breaking out of their conventional manufacturing mindset in the early-phases of the design process. As only limited methods aimed at addressing this need exist, this thesis proposes to develop a set of Design Heuristics for Additive Manufacturing (DHAM) that focus on transferring early design phase-relevant AM-process independent knowledge and capabilities to both novice and experienced designers.
First, 18 characteristics for early-phase Design for AM (DfAM) methods are synthesized from literature, which later guide the derivation and validation process. Then, a set of 25 DHAM are derived from a pool of 275 AM artifacts gathered from literature, industry, the media, and hobby websites. These 25 DHAM are divisible into eight thematic categories: part consolidation, customization, information communication, materials, material distribution, embed-enclose, lightweight, and reconfiguration. Another literature investigation indicates that the delivery format of the DHAM should be multi-modal and consist of a combination of text, images, abstract and concrete examples, and physical objects in order to aid understanding, design by analogy, and creativity. As such, accompanying cards and objects are developed. The cards contain a mix of text and visual examples, and one object that physically represents the heuristic is designed for each DHAM.
It is found that the current standard for the validation of early-phase DfAM methods is not in alignment with good design research practice, so a four-phase validation procedure is proposed. The four phases are verification, controlled validation, workshop/project validation, and comparison to other methods. This procedure is used to validate the DHAM and its delivery format. First, in the verification phase, the DHAM are applied to two case studies to demonstrate their feasibility. Second, the controlled validation phase is conducted. Four controlled user studies are conducted to (1) validate the DHAM; (2) validate the DHAM cards in an individual design scenario; (3) validate the DHAM cards in a team design scenario; and (4) validate the DHAM objects. In each of these user studies, novice designers complete one of two redesign tasks. In Study (1), it is shown that the DHAM stimulate the inclusion of more AM concepts in the generated designs and cause users to make more AM-relevant modifications to their designs. Next, in Study (2), in addition to confirming the findings of Study (1), the cards are shown to stimulate the inclusion of more of the unique capabilities of AM in the designs and increase AM-novelty and AM-flexibility, while leaving the quantity of concepts produced by the participants unaffected. Then, in Study (3), in addition to the previous findings, the cards are found to increase both general novelty and variety among the teams. Finally, Study (4) demonstrates that the objects in concert with the cards produce the same effects seen when only the cards are used. However, when comparing the variety of Studies (3) and (4), one finds that the variety of concepts generated is higher when the participants have access to both the cards and objects.
Following the novice user studies, the third phase of the validation procedure is conducted, workshop/project validation. This phase is completed by conducting three industry workshops with a total of 19 participants at three different companies. During each three-hour workshop, the participants apply the DHAM to their chosen product in an ideation session. Following the ideation session, they provide verbal feedback on the DHAM and rate the ability of the DHAM to fulfill the 18 criteria for early design-phase DfAM methods. All three companies react positively to the DHAM, particularly the objects, and they see the DHAM not only as a good ideation tool, but also as a way to teach AM novices about AM. However, they would like more examples to be included and more information about how to take the next steps regarding the various AM possibilities presented by the DHAM. Based on the ratings provided by the workshop participants, the DHAM fulfill 16 of the 18 criteria for early-phase DfAM methods. The DHAM score low on the ability to communicate information about the restrictions of AM (expected) and on being AM-process and material independent (unexpected). Finally, the DHAM are compared to other methods by comparing them to the most similar pre-existing method, Design Principles for AM developed by Perez (2018). They are found to induce similar effects, but the DHAM are more comprehensive and focused on the opportunities afforded by AM.
Based on the evidence gathered through the validation procedure, the DHAM are found to fulfill their stated goal of transferring early design phase-relevant AM-process independent knowledge and capabilities to both novice and experienced designers. Thus, the contributions of this work are six-fold. First, the community consensus on the requirements for early design phase DfAM methods is determined. Second, the community’s knowledge about delivery format and modalities for early-phase DfAM methods is summarized and reviewed. Third, 25 DHAM, along with accompanying cards and objects, which are focused on the needs of designers in the early phases of the design process are proposed. Fourth, the ability of the DHAM are to stimulate the inclusion of AM concepts and their positive effect on creativity in a variety of novice and expert design scenarios is shown. Fifth, appropriate use-case scenarios for the DHAM are determined. Finally, a basis for validating early-phase DfAM methods and evaluating their ability to stimulate the inclusion of AM concepts and their effect on creativity is proposed. Future work should include determining the cause of the low rating from industry regarding process and material independence and directly comparing the DHAM to other early-phase DfAM methods in controlled user studies
