## 2 Results of Literature Analysis
### Content Analysis
#### 2.2.2 Process
The review shows that inventory and warehousing are crucial in managing the supply of spare parts. However, the provision of AM can create lower inventory and reduce the need to have a larger volume of space, technology, and manpower to handle such inventory, thus reducing costs. * _Logistics_ Only a few studies deal with the logistics aspect of AM. As mentioned earlier, the adoption of AM may make some of the logistics specifically related to production management and some parts of transportation redundant. AM adoption may eliminate some parts of the SC, thus making the network shorter and with fewer players. [PERSON] [1] studied an integrated job and vehicle scheduling problem using best-fit heuristics to minimize the makespan in an AM SC. The author found that the best-fit capacity utilization-based selection (BFCUBS) algorithm is superior to other methods in improving the make span. Similarly, [PERSON] [50] studied the integration of additive manufacturing with JIT delivery systems with the aim of minimizing delivery times and transportation costs. The authors used a branch and price-based methodology for integrated machine and vehicle transportation scheduling problems. A location-dependent cost minimization SC optimization model was developed by considering the sum of production, transportation, and inventory costs. The author mentioned that the integration of production and transportation can result in cost savings for companies. [PERSON] et al. [10] focused on the modeling of service logistics with AM by using an analytic hierarchy process to rank the spare parts in terms of their value by focusing on attributes such as the demand rate, resupply lead time, safety stock costs, the number of supply options, and supply risks. The potential for value improvement was analyzed in terms of reduction in costs such as manufacturing, ordering, direct parts use, safe stocks, and supply disruption. The author mentioned that the development of such a rank can help the company design a better after-sales service. The configuration of SCs for additive manufacturing in different facilities was studied by [PERSON] et al. al [5]. The authors proposed a simulation model which simulates the installation of 3D printers in a company's internal facilities where various SC designs were changed between the model runs. They measured the performance of the SC centres with the following key performance indicators: service level, production, lead, inventory level, stock-outs, and supply costs and times. The proposed model is not only able to test the impact of additive manufacturing but can also test the impact of removing and adding internal facilities, external suppliers, and products of SC. * _Resource Allocation_ The allocation of materials and 3D printers can be considered for resource allocation. Some studies investigated 3D printer allocation in sites and facilities in the context of AM [5; 25]. To quantify the cost and classification of spare parts, [PERSON] [58] proposed a multi-stage process model which serves as a decision support tool for spare parts allocation. The focus was on different spare part allocation strategies, including stockpiling, the conventional production of spares, and AM strategy. The author incorporated various cost components in the proposed cost modeling for spare allocation strategies, including the AM preprocessing and postprocessing costs, setup and preparation costs, building job assembly costs, and part building costs. [PERSON] [38] studied the optimal deployment of 3D printers in different facilities for spare parts production by utilizing classical p-median, location-allocation modeling, and mixed-integer linear programming. The model was tested for the optimal scenario through an elevator maintenance case study with nine production centres, each with a 3D printer. The study mentioned that this type of optimal analysis would help companies manage challenges at different locations where AM is adopted. [PERSON] et al.