College of Engineering
Mechanical Engineering Department
BS in Mechanical Engineering
This Final Design Review (FDR) documents the work done by the group to manufacture the system to deliver improvements to the furnace in the Cal Poly microfabrication laboratory (better known as the cleanroom). The document describes the material covered in the Scope of Work (SOW), including background research, customer needfinding, and the problem statement, material associated with concept development and selection for Preliminary Design Review (PDR), material detailing the design and manufacturing plan of the system for Critical Design Review (CDR), and new material detailing the manufacture of the system for FDR.
Research done for the SOW resulted in a list of engineering and customer specifications. These in turn led to the development of the goal of the project: to make the furnace system more user- friendly to operate by simplifying the tubing layout, introducing digital control, and creating a consolidated user interface.
Following the development of the problem statement, the problem was decomposed into its individual functions, and solutions developed for each function. These solutions were analyzed, and the best were combined into a final design. The solution is a system consisting of a tubing subsystem, a user interface, and a control subsystem to connect the two. A prototype system has been designed to test key functionalities of the control system, and design, manufacturing, and test plans have been created for the subsystems.
The system was intended to allow the user to set up a temperature and gas program, start the run, and not interact further with the system until the end of the run. In the event of an unsafe condition detection, the system would raise an alert (it was assumed that users would remain in the room as a matter of safety during runs). The fluid lines were vastly simplified, and gas programming is performed on a touchscreen user interface connected to a Raspberry Pi board. It was originally intended to be able to perform temperature programming on the same interface, but this functionality has been removed from the project as a matter of safety, as requested by the sponsors. The new interface and all controlling functions run on software written by the team, which is publicly available and free for any subsequent project to modify and use. The openness of this setup allows further improvements to the electronics and software as necessary.
The system was mostly built as designed, although several key functionalities are incomplete. As such, the system was not installed in the cleanroom. Therefore, finishing the remaining components and installing them in the cleanroom are tasks which are left to subsequent senior project teams.
Next steps for subsequent projects include implementing bubbler refill, building a graphical user interface for the gas routing system, implementing communication with the thermocouples, installing the pressure monitoring system, and implementing automatic gas switching. After this, the system may be installed. Upon installation, the original gas programming interface will be retained, and the new system will be installed so that it will be possible to throw a switch to revert to the old interface in the event of system malfunction.