Preliminary Detailed Design
Table of Contents
Team Vision for Preliminary Detailed Design PhaseDuring this phase:
- We visited the Brinkman Lab to discuss our frame and determine the best size 80 20 to use and to discuss possible ways to insulate our heater sub-system. We also acquired a 2’6”x4’ diamond plated aluminum sheet.
- We visited Dr. Stevens to further discuss the heater sub-system and think of ways to hold the heat a temperature or range.
- We evaluated and remodeled each subsystem to determine how they would interact with the frame and perform the desired tasks.
- We updated our 3D model and switched over to Onshape to allow easier access for the team.
- We researched and determined how vertical motion was going to be obtained for the plastic frame.
- We purchased plastic sliders and an air tank.
- We obtained some preliminary plastic which will be used in testing.
- We set up a testing rig to evaluate vertical motion of the plastic frame.
- We researched the ASTM standard for surface touch temperature.
- We continued to refine our BOM and improve our price estimate.
Feasibility: Prototyping, Analysis, Simulation
Pain Threshold: 111 degree F Max Pain: 140 degree F Our Goal Limit: 120 F
Vacuum Tank Pressure TestTo verify that the tank can withstand the vacuum conditions needed and that the vacuum pump system can reach the desired vacuum pressure.
Vacuum Tank Test Procedure
- Connect the vacuum tank to the vacuum pump along with a vacuum pressure data acquisition unit.
- Inspect tank for any defects.
- Start the data acquisition and the vacuum pump.
- Monitor the vacuum pressure values and the tank.
- Once pressure values remain stagnant for a significant period of time, about 30 seconds, turn off the vacuum pump and monitor the pressure to see if there is any significant loss of pressure.
- Turn off the data acquisition system.
- Slowly release the pressure in the tank back to atmospheric conditions so that the system can be disassembled.
- Analyze pressure data and reproduce graphs to confirm vacuum draw rates.
- Repeat the test with various vacuum pump systems to compare.
Heating Temperature Test
Our previous visits to vacuum forming industries and research have told us that generally our ovens should remain at 300 degF to heat our plastic. In order to confirm this, we plan to do our own test. Using a simple box and a kitchen oven, we will heat the plastic at 300 degF to examine time to reach mold-ability, sag, and forming quality of the plastic at that temperature. We have acquired enough plastic to test PETG and HIPS at 300 degF, and at 400 degF.
- Create simple wooden test box
- Pre-heat oven to 300 degF
- Staple plastic sheet tight across top of test box
- Place test box in oven, plastic sheet side up
- With oven light on and oven door kept shut, watch plastic
- When plastic sags as far as possible without ripping plastic, remove test box
- Record time to reach optimal sag
- Quickly push plastic over mold object and hold down until plastic hardens
- Remove plastic from box and mold from plastic to examine test mold
- Repeat process with oven at 400 degF
Linear Slider Load TestSince our design designates that the plastic sheet is the only moving part of assembly for the forming process, we have created a plastic clamping fixture that is to slide vertically. The plastic clamping fixture will be a square that fits inside the frame of the whole assembly with a linear slider attached at each corner. Each slider will be created using an angle bracket with plastic slider material that fits in 8020 track. Our biggest concern with this part of the design is racking of the plastic clamping fixture as it moves up and down. Our goal is to restrict movement as much as possible to smooth vertical sliding. We have designed a test to make sure our sliders are capable of carrying the load required, and that they slide smoothly.
Slider Load Test Procedure
- Create the slider by drilling holes in each face of a piece of angle bracket, and screwing the plastic slider onto it.
- Attach the slider to a rigid rod that should sit perpendicular to the direction of motion of the slider.
- Slide the slider piece onto a piece of 8020 track at least 4' in length.
- Secure the 8020 track vertically.
- Apply a vertical load to the horizontal rod, and slide vertically up and down the track.
- Monitor the motion of the slider, and how the load affects movement.
- Increase the load on the horizontal rod and continue to monitor.
- Continue to increase the load until at least 20 pounds (slightly higher than the calculated weight of the plastic clamping fixture).
Drawings, Schematics, Flow Charts, Simulations
Bill of Material (BOM)
Plans for next phase
- Spec out and acquire heater element s
- Finalize Solid Model
- Determine available roll sizes for plastic
- Begin building and testing sub-systems separately
- Source electrical components
- Order confirmed components