High Pressure Testing
Test Apparatus and Manifolds.
Overview
Key Challenges
Tight time constraints
Staying within budget
Working remotely
My Role
Mechanical Engineer - Team of 1
Synapse Product Development
San Francisco, CA
Skills Applied
CAD Modeling (SolidWorks)
In-House Fabrication
Cross-discipline collaboration
Design Reviews
Year
March 2020
About
The test apparatus was designed to test client prototypes along with prototypes developed by Synapse team members. It was designed to test various subsystems of a device, however, I primarily worked on testing water pressure.
The project consisted of designing and fabricating the test apparatus and designing two sets of manifolds to measure water pressure. The apparatus was used by multiple team members and is in current use by the client.
System Overview
Dry Compartment
Wet Testing
Spill Tray
Requirements
1. Controls the spray of water and protects hardware from getting wet.
2. Includes a system to collect water.
3. Fits under cabinets when mounted on the counter in the lab.
4. Intuitive for team member and client use.
5. Measures high water pressure.
6. Tests various subsystems of client prototypes.
7. Is adaptable for future prototypes.
Concept Ideation
I began my design process by ordering an OTS spill tray and choosing a location where testing would occur in the office. I measured the dimensions of the available space and set parameters for the maximum size of the apparatus. I proceeded to sketch ideas for an 80/20 frame that could meet the requirements.
My first concept was an 80/20 frame with acrylic panels that would serve as a spray control box. The testing unit would sit outside of the box because it cannot get wet. The prototype that sprays water would be inserted through a door at the top of the box. The pressure sensors would also be outside of the box to stay dry.
After running a few tests on the prototype, I realized that all of it would need to be in the spray control box because it was leaking water in unexpected places. The testing unit would also need better protection from splashing water. I sketched a new concept with a wet compartment and a dry compartment.
I sketched my final concept in SolidWorks. I decided to move forward with the idea of having a wet compartment and a dry compartment. The main change I made was moving the door to the wet compartment from the top panel to front panel. This would allow electronics to sit on top of the apparatus, and would be easier to load the prototype in and out.
Fabrication
I created a detailed set of instructions on how to fabricate the test apparatus. This deck was intended for the client or Synapse team members to recreate the test apparatus for future prototypes. I include a BOM, instructions, and future recommendations.
Pressure Testing
Manifold for Test #1
The manifold was designed to perform high pressure testing for a client prototype. The requirement was that it needed to port water to 8 different pressure sensors to measure the individual pressure in 8 channels. The key challenge was creating swept cuts in SolidWorks to get around screws that could not be moved. The walls of the channels needed to be at least 2mm thick.
The part was sent out to be 3D printed by a prototyping company. Once my team member received the part, the holes for the pressure sensors needed to be tapped. The pressure sensors were covered with rubber for water proofing.
I selected the pressure sensors based on burst pressure, supply voltage, response time, accuracy, and diameter. The manifold and sensor system was able to effectively test water pressure, but modifications needed to be made on the next version for more accurate readings.
Manifold for Test #2
I designed a second set of manifolds to test a newly developed prototype. The modifications I made are listed below:
1. Reduced print material to lower cost.
2. Drafted channels to port water to smaller scale prototype.
3. Added bleed holes to release air bubbles that may be trapped near pressure sensors during calibration. Pressure readings were inconsistent when using the first manifold due to trapped air.
A major difference between the first and second sets of manifolds was the interface with the prototype. The first manifold was simply clamped down with four screws. The second manifold needed to be completely sealed to the prototype with epoxy and clamped down with a center screw. A locating pin would assist in accurately lining up the channels. A tolerance analysis was conducted to ensure the holes were as small as possible.
Conclusion
Synapse began working remotely in March 2020. The day after the apparatus was built, it was passed around to the homes of multiple team members to conduct tests. The test apparatus was successful in testing two prototypes and providing meaningful results to the client.
I was able to virtually lead design reviews for the manifolds and communicate with team members for shipping parts to each other. This project is an excellent example of how my team collaborated to test a physical product during a time of remote work.