## 3 System Architecture of the Proposed IPSS Maintenance Assistance Platform  
The proposed methodology aims to build an Intelligent PSS (IPSS) solution that will improve maintenance throughout its lifecycle, taking into consideration the Energy Demand Management of the provider. As such, by improving and expanding existing services, businesses contribute to aspects such as customer satisfaction and loyalty, as well as financial and environmental sustainability by producing a limited number of high-value products. PSS can also be considered a dematerialized solution due to the reduction in the environmental footprint [63]. The proposed IPSS maintenance assistance platform will facilitate manufacturers in increasing the added value of their tangible products through the provision of a product-oriented PSS. Both the company and the customer will benefit from this approach. Customers will benefit from robust and high-quality maintenance support, and the company will gain a significant competitive advantage over competitors. The main module of the proposed system architecture is the AR module. This module is based on the implementation of a precedence algorithm, which in turn facilitates engineers during the development of user-interactive AR instructions for both assembly and disassembly, and guidance steps for performing inspection tests on the manufacturing equipment based on suggestions from a knowledge repository which is saved and updated on a Cloud Database [64]. Further to that, data acquired from sensors which are integrated on the manufacturing equipment are also saved to the Cloud Database and are retrieved in order to facilitate shopfloor technicians and engineers in performing the diagnostic tests on the equipment. Four parties are involved in maintenance:  
* The customer, who retains the ownership of the tangible product and uses the maintenance service;
* The engineer department, which consists of the expert engineers who are responsible for tracking the progress of the maintenance activities as well as to generate the shopfloor schedule;
* The energy supplier, who can predict energy consumption and provide suggestions for improving the schedule of the mold-making industry;
* The shopfloor technicians, who are in charge of the maintenance tasks. Taking into consideration the people involved in the maintenance of the manufacturing equipment, in the proposed system architecture the following five (5) teams/user groupshave been formalized. The formalization of the people facilitates the creation of the different functionalities of the framework and is used to regulate the type and level of information to be displayed on each group. * Customer: The people of this group are capable of sending and receiving information about the operating parameters of the equipment. In addition to that, they can also request to plan the maintenance of their equipment in collaboration with the service provider and receive quotations regarding the maintenance activities/spare parts required for repairing/restoring their equipment. * Engineer: This team/user group is responsible for keeping track of the progress of the maintenance processes; they gather feedback from 3D annotations and create the Bill of Processes (BOP) and the Bill of Materials (BOM). * Shopfloor technician: Diagnoses faults, determines product code, creates annotations, and has access to the AR tool and database. * Energy supplier: Obtains data regarding the processes involved in the MRO operations and provides alternative schedule solutions. * Administrator: The administrator is a supporting team, with rights and access to the whole system, in order to ensure the seamless operation of the framework. A detailed representation of the system architecture, including the steps, and the information flow in each step are illustrated in Figure 3. The first step in the framework presented in Figure 3 is the collection of data from the integrated sensing system on the manufacturing equipment (please refer to Step 1 in Figure 3, in the layer denoted as customer side).