G10 Blog 4



Blog 4

    During the period of November 11 to November 25 the team worked mostly on generating a production plan. This involved sourcing buyout materials, tabulating a lead time for ordered parts, outlining the manufacturing process, and exploring potential places to execute manufacturing processes.

    Table 1 shown below shows the compilation of the research and includes the cost of the items including tax, its purpose, and the vendor the team has identified.




Table 1: Items needed for Manufacturing Process 



    Table 2 shown below shows the manufacturing processes the team has identified that will be needed to build the prototype. For each process, the expected time duration has also been identified and as a whole the manufacturing process is expected to take 64 days from start to finish.



Table 2: Estimated Time for Each Manufacturing Process



Other details in the manufacturing process have also been decided by G10 which include:
  • The material will be melted and poured into a cast

  • The fins will be machined out of casting with a circular saw

  • Porting will be drilled out after fins are cut on a drill press

  • The groove will be cut by hand with a Dremel using a grinding wheel to achieve a smooth finish
    
Currently, the team is working on generating 2D drawings for manufacturing and on publishing a project execution timeline.


    The team's final design features an aluminum casing that encloses the motor, ensuring both waterproofing and cooling. The final design is shown below in Figure 1. The casing includes two arrays of 15 identical fins for heat dissipation. The motor, positioned within the casing, is surrounded by thermal pads that conduct heat away and dissipate it into the air through the fins. While the team considered alternative cooling methods, such as employing copper instead of aluminum and incorporating a fan, we ultimately believe that the current cooling approach is adequate and the other methods would be excessive while being much more expensive and complex. Under all calculated ambient conditions, the fins effectively maintained the motor temperature below 105°C, assuming the casing temperature and motor temperature are similar. The motor will be sealed to the wheelchair's flange, which is the opening where the motor shaft connects to the rest of the wheelchair. The transmission beyond the flange is waterproof. To achieve this, the casing will be sealed with silicone, specifically with a durometer of 55A. This seal is designed to endure water pressure of up to 600kPa, significantly exceeding the required 10kPa for waterproofing at a depth of 1 meter.




Figure 1: Final Design of Casing

After the fall semester, the team will order all the necessary parts for the prototype. Construction of the casing will commence over the break, involving the creation of molds for sand casting. The aluminum will be melted and poured into the sand molds to form the main casing structure. Following this, the machining of holes, fins, and other details will take place. The team aims to complete casting and begin machining before the start of the spring semester.

Comments

Post a Comment

Popular posts from this blog

Blog 7- G10

Image
Blog 7 Between March 9th and March 23rd, the team mainly focused on machining the casted prototype. The cast had some imperfections due to air pockets forming which ended up creating holes. These holes were mostly concentrated in a small area in the fins shown in Figure 1. The team believes that the holes would not substantially affect the functionality of the device other than a minor decrease in thermal performance. The team could redo the cast and make another prototype but a minor loss in thermal performance is not worth the time to recast the prototype. Figure 1. Holes on one side of the cast. After the team decided to keep the cast, the fins were machined. The fins were made slightly thicker than originally planned to reduce the chance of them breaking since the holes had already weakened the structure. Based on the heat transfer calculations from semester one, the new fin design still provides enough cooling to prevent overheating. Figure 2 shows the current machining progress ...
Read more

Blog 1 Capstone - Team 10

Image
Blog 1   Over 3 million Americans use an Electric Wheelchair and among them, a popular wheelchair is the Action Trackchair. This special wheelchair is designed for users to be able to move around in all types of terrains.  This allows the user to traverse rugged terrain easily, providing mobility and access to areas that would otherwise be challenging to navigate on a more conventional wheelchair.                           Figure 1: Action Trackchair ST (Front)                                                                                 Figure 2: Action Trackchair ST (Back) Among the users of this wheelchair is one of our Team Member’s brother. He along with ...
Read more

Blog 3 Capstone - Team 10

Image
Blog 3  Team 10 has been working on designing a casing for a wheelchair motor that waterproofs and cools it. For the duration period from October 28th to November 11th, the team has completed its second milestone which was performing the analysis for simulated models and entered its third milestone which is generating a production plan. The work completed for the second milestone specifically includes performing the heat transfer analysis for the fins and performing the pressure calculations for the seal. For the third milestone, the team has started with identifying all the potential materials that will be required to build and install the casing. When the team performed heat transfer calculations for fin dissipation, we realized that the initial constraint of keeping the casing exterior below 44°C was unrealistic due to the casing's low Biot number of roughly 0.003. The casing's extensive surface area compared to its volume, coupled with high thermal conductivity, results in ...
Read more