My Mechanical Engineering capstone team and I redesigned GE's armature impregnation system
In my Mechanical Engineering Capstone, my team had the opportunity to work with GE Aviation. We analyzed their armature impregnation process – a step in the manufacturing process for a component of their brushed DC motors – and identified a few key issues.
We focused on improving two primary subsystems: the mechanism used to hold armatures, and the mechanism used to set the height of the varnish during impregnation. And throughout the testing, prototyping, and manufacturing of our enhanced impregnation system, I helped my team visually convey the new systems we designed.
All graphics on this page were created by me throughout the project.
GE Aviation - Rockford, IL // Mechanical Engineering Capstone
September 2020 – March 2021
Zach Shonfeld, Christopher Lee, Daniel Lopez, Benjamin Smith, Danielle Tolsma, Bohan Yao
Project Management / Visual Design Communication / Prototyping and Testing / Client Communication / Waterjet Operation
Takeaways.
This design process focused on improving an existing system rather than conceptualizing and creating an entirely new product, which helped me gain experience innovating within existing framework and focusing on meeting specs.
I had the opportunity to manage our project – working to make sure we were communicating effectively, learning from our failed tests, and frequently assessing our progress to ensure we were taking new developments into account.
If you are interested in learning more about our design process, feel free to explore the project details below!
What is impregnation? And what does GE's original process look like?
Armature Winding Coil Impregnation:
• The process of applying varnish to an armature winding coil and then curing it to provide insulation and mechanical stability
• Armature (shown in the figure): rotating coil + shaft in a motor
GE's Impregnation Process:
• GE utilizes Vacuum Pressure Impregnation (VPI), which can be broken down into three main steps:
1-2. Load – put armatures into a pressure pot
3-4. Apply Varnish – transfer varnish into the pressure pot, apply pressure to circulate the varnish through the winding coils, and drain the varnish
5. Cure – clean the excess varnish then cure the armatures in an oven to harden the varnish
Key Issues:
1. Can only accommodate one armature size at a time
2. Cannot easily identify varnish level; rely on operator intuition
The team first focused on redesigning the armature holder subsystem to accommodate a range of armature sizes.
Armature Holder Goal
The varnish cannot rise too high up the armature, or it will be very difficult to clean before curing.
Thus, to accommodate multiple armature sizes, the armature holder aimed to align the middle of the stacks of each armature, as seen in the graphic.
Armature Holder Design
Our team designed a modular, tiered grate system, water-jet from stainless steel sheets.
• Three levels (Low/Mid/High)
• Each level has three interchangeable "slices" that cover 1/6, 1/3, and 1/2 of the base hexagonal grate
• Modular design to accommodate as many armature combinations as possible
Through testing and client feedback, we also implemented label cutouts to signify the height of each slice when looking down into the pressure pot and extra holes for increased drainage.
I led the development and testing of an overflow system to simplify setting the varnish height.
Original System Problem
GE's original VPI system had no method to consistently set the varnish height. Rather, it relied on operator approximation each cycle.
Solution: An Overflow System
We worked through several ideas to reduce the variability in the original process. Due to its simplicity and accuracy, we implemented an overflow system.
The operator looks through a sight valve and stops the flow of varnish once it begins to overflow, then the varnish settles at a consistent height – drastically reducing the possible error in the process.
We brought our redesigned subsystems together to create an analogous VPI system.
Our analogous VPI system simulated the working environment at GE, while allowing us to test our subsystems without disrupting their production process.
We conducted a study to analyze the client's original vacuum and pressure levels, and we worked to validate our new overflow system and varnish replacement system (which helped the client easily replace old varnish).
