# The Impact of Additive Manufacturing on the Flexibility of a Manufacturing Supply Chain
## 1 Introduction  
Supply chain management plays a critical role in organizations, particularly in ensuring smooth and efficient production runs with changing patterns in demand [1]. Recently, fluctuations in demand have been caused by factors such as product customization, which has become more commonplace, which in turn lead to shorter product life cycles. Other factors such as increased competition and the rise of globalisation have also played a part in demand fluctuation. All of these factors have made it imperative for organisations to be flexible in order to survive in the long-term, whether that means adjusting production to meet higher or lower levels of demand, or in having the ability to adapt and produce customized products or services that can effectively meet customer needs [2, 3]. Where flexibility is well-developed and becomes the modus operandi for a business, this can help manufacturing firms respond to changes in customer requests that may come in the form of increasing, decreasing, cancelling, or changing the timing of orders [4]. Naturally, all of these changes in the marketplace have made it difficult for manufacturing firms to operate in isolation and prosper; therefore, collaboration has become a necessity, as has the need to redefine flexibility, by increasingly viewing flexibility from the lens of the supply chain e.g., [5, 6]. In pursuit of developing such capability, firms are considering Additive Manufacturing (AM) [7], commonly known as 3D Printing, as a technology that is capable of fabricating products directly from digital files without the need of tooling or moulds [8; 9]. Unique characteristics of this technology such as lack of tooling, on-demand production, freedom of geometry and the consolidation of assemblies into single components have led recent studies to suggest AM as a technology that could improve flexibility e.g., [3; 8; 10]. What has not been studied however are the consequences that might occur when adopting AM to improve flexibility, mainly due to essential trade-offs that must be made during the process of adoption. The first aspect of these trade-offs concerns the relationship between flexibility and cost. While adopting AM technology may increase supply chain flexibility in some aspects such as volume, it can, at the same time, lead to a decrease in other competing aspects such as cost. This potential trade-off is critical because, in reality, manufacturing firms operate in different environments and under different market conditions and some companies may find it more beneficial to prioritize efficiency over flexibility [11]. Relying on dedicated manufacturing technologies (i.e., to manufacture core products with high volumes), as opposed to flexible ones, may therefore be appropriate for these manufacturing firms. For instance, standard products with predictable demands, such as water bottles, would not require as much supply chain flexibility as products in the fashion industry. The significance of this distinction cannot be underestimated because adopting AM for industries that do not require many product variants or do not have uncertain demand may lead to unnecessary higher unit costs. This view has been highlighted by [PERSON] [12], who stresses the importance of carefully assessing the target flexibility level to avoid unnecessary costs. In fact, it has been demonstrated that enhancing supply chain flexibility in certain contexts can be counterproductive [13; 14; 15]. The second trade-off issue to consider in terms of using AM to improve flexibility is that flexibility itself is not a standardised capability; rather, it is a competency with many layers and aspects that must be customised for a given context [16]. Responding to the disparate changes in demand may require a different type of flexibility on each occasion. For instance, changes in volume demand require volume flexibility, while the ability to respond to different customer preferences and choices may require mix or process flexibility.