Mechanical Design of a Smartphone Grading Device

The research of this thesis is concentrating on the design process of the mechanical components of a smartphone grading device. The output of the grading process is a grade that represents the condition of the smartphone. This kind of grading is used to determine the value of second-hand smartphones and to evaluate whether it is worthwhile to refurbish a phone with defects. The grading process is currently done mostly manually, and the market needs an automated device that can perform grading efficiently and with good fidelity. This thesis is made to OptoFidelity Oy, which is a company that has expertise in the field of test automation and robotics. They have the capability to develop a device that can fulfill the market’s need. The objective of the thesis is to find out what methods and design decisions can be used to make cost-efficient designs of the mechanical components while fulfilling the requirements of the device. Functional and physical requirements are presented based on the principles of the requirements engineering. Standards and directives are studied for defining the safety and ergonomics requirements for this kind of machinery. The design processes are implemented following the guidelines of the VDI standard 2206:2004, which encompasses the V-model and cycle of the problem-solving. The standard is developed for helping with the design of the mechatronic systems. Research methods include benchmarking and a literature study concentrating on materials, manufacturing processes, and components’ costing. The design is done by following design process models and it includes the use of the method of solution variant analyses, which is concentrating on manufacturability, functioning, and cost. This method is used for the design of critical sub-assemblies. The results include the design decision and analyses of the methods that were used to make the cost-efficient design of the device and its critical sub-assemblies. The most suitable options for the critical components are chosen based on the analyses that are done as a part of the cycle of the problem-solving process. The enclosure is decided to be manufactured from steel with a sheet metal work process. The frame structure is decided to be implemented with the machined aluminum plate that is installed onto the frame, which is built from standard aluminum profiles. The smartphone is moved with rollers that are decided to be machined from polyurethane. The base blocks of the mover unit are decided to be machined from aluminum and finished with a black anodizing coating. The device is going to be manufactured based on these design results. OptoFidelity should pay more attention to having clear design processes and proper requirements elicitation in their projects. It is recommended to develop a template for requirements engineering and use more resources for verification of the system elements already in the earlier stages of the design process. This thesis presents several design decision guidelines that can be used as a reference for finding cost-efficient solutions when designing mechanical components