Preliminary Detailed Design
Team Vision for Preliminary Detailed Design Phase
What is our plan?
- Finalize the overall system design and run an analysis of our necessary sub-systems in order to ensure that the entire process is feasible and completes our requirements
- Outline all of the components necessary to build our bottle up-cycling system
- Begin purchasing of high priority materials
- Finalize the design of the final product including the attachment mechanism and the overall dimensions
What have we completed?
- Created a system architecture in order to connect all of the subsystems
- Ran feasibility testing of compression and heating for our system
- Chose the materials to be used for the complex components based on strength and thermal properties
- Altered our design from compression molding to a Transfer Molding process
- Created a final product design with an interlocking mechanism
- Created a Bill of Materials for all the necessary components to build our system and the resulting price as compared to our budget
- Updated our risk assessment and created test plans to properly measure our engineering requirements
Design and Flowcharts
Updated System ArchitectureOur system architecture has been updated to include specific parts that will carry out the various functions of the system as well as notable interactions between such parts.
Feasibility: Analysis, Simulation
Chip Input FeasibilityThe density of the plastic chips was found by massing a known volume of the chips acquired from Tycom Recycling. The mass of the chips input into the machine must be the same as the mass of the gutter after extraction, with an additional mass in order to over fill the mold. The mass of the gutter was found by multiplying the density of PET by the volume of the gutter. here.
Heat Transfer MechanicsThe energy needed in Watts to heat the melting chamber and PET plastic was found by calculating the energy per mass divided by the time to heat for both the plastic and the chamber as well as the heat of fusion for changing the plastic from a solid to a liquid state. With these initial calculations, the energy required came out to about 145 Watts. However this is excluding the losses to the environment that will inevitably take place and sap heat from our chamber. We hope to reduce losses by adding insulation for the entire heating chamber, thus lowering our input energy. These calculations will help us choose the resistance heater that will be ideal for our system. here.
Mold Compression FeasibilityThe metal mold will be experiencing compression at an elevated temperature well above room temperature. The materials we have proposed at this point are the aluminum alloys AL 6061 (common), AL 2011 (higher machinability), AL 7075 (high strength), and steel AISI 1018 (common).
The yield and ultimate strengths of the aluminum alloys are observed to decrease with increasing temperature. We have initially concluded that the fatigue strength will also decrease at the same rate. These strengths of the aluminum alloys at our working temperature of 260 degrees Celsius are seen to be roughly 9-12% of their maximum strength at room temperature. Using this, the fatigue strength at the working temperature can be calculated from the available value of fatigue strength at room temperature.
The key assumptions included within these calculations are as follows:
- Fatigue strength at working temperature is proportional to yield strength at working temp. compared to room temperature
- The working temp is 260 deg. C
- Use a modified fatigue strength because the working temperature is much higher than room temperature
- Gutter dimensions are 30.48 cm x 15.24 cm x 7.62 cm
- Additional 5cm on each side and bottom of the gutter cavity
- The mold is acted on the surface by the car jack circle diameter
- Typical car jack support diameter, d=10cm
- Shear strength at working temperature is proportional to yield strength at working temp. compared to room temperature
- Bottom of mold is 5cm thick
- Use bottom thickness and width for minimum shear area and maximum shear force
The working mold compression feasibility calculations can be found here.
From the calculations above for Aluminum 7075, the max force we can apply to the heated mold prior to deformation is 153.9 kN when considering fatigue strength and 516.1 kN when considering shear in the smallest cross section of the mold. These values are highlighted in green.
Aluminum Type Comparisons
Based on our feasibility analysis we have decided that AL 7075 is the best suited for our build. Although it will require more energy to heat and will retain the heat for longer, it has a higher durability under pressure and will be able to withstand higher forces without deformation. The integrity of the mold takes priority over the energy required to heat our mold.
Justification for Using Steel
Since steel has a lower thermal conductivity as compared to other metals, it will retain heat for longer. If we add insulation to further reduce heat loss, it will allows us to keep our heating chamber at a high temperature for a long period of time. This will reduce the overall time between cycles because there will be less time spent reheating the chamber. Steel is also stronger than aluminum and will be able to withstand the pressure needed to transfer the plastic into the mold. Since this system will be running multiple cycles per day, the repetitive application of compression forces will cause wear on the material and steel's higher fatigue strength means it will hold up for longer.
Our Current Design
End Product Design & Prototyping
The customer requirements helped to guide the design of the gutter and the following checklist allows us to monitor and ensure that our product is meeting our customers' needs.
A engineering drawing of the product design can be found here.
The prototyping we are currently working on includes 3D printing a shortened model of the gutter to investigate methods of attachment between gutters and to buildings. Here is a picture of the 3D printed 4 inch gutter section.
From our prototype, we will be able to investigate the attachment method connecting individual gutter sections and the structural integrity of the assembly. Results from these analyses will allow us to iterate our product design and move forward with designing the product mold.
Bill of Material (BOM)The Bill of Materials for our current design is broken up into the following aspects:
- Mold Aligment
The working Bill of Materials can be found here.
Test PlansOur test plan for experimentally verifying the engineering requirements are broken up into the following categories:
- T1 - Observations not requiring tools
- T2 - Length measurements
- T3 - Weight measurements
- T4 - Temperature and heat testing
- T5 - Efficiency
- T6 - Compression testing
- T7 - Safety
- T8 - Chip input size testing
- T9 - Product strength testing
- T10 - Surface roughness
The working Test Plans can be found here.
These Test Plans were formulated from the Engineering Requirements, which can be found here.
The Test Procedures to describe the testing processes can be found here.
The layout of these Test Plans were based off of the Test Plans from the prior design group P13027
Updates to our Risk AssessmentNew Risks:
- R29-Production rate of machine is too low to be economically viable in Nicaragua.
- R30-Gutters will not be able to be attached to homes
- R31-Gutters will not be able to attach to themselves
- Several risks have been mitigated by sourcing and acquiring plastic chips from Tycom Recycling (R1, R8, R13, & R18).
- Changing to transfer molding has mitigated additional risks (R5, & R22).
A working Risk Assessment file can be found here.
Design Review MaterialsOur Preliminary Detailed Design Review will take place at 11:00AM on Thursday, November 9th in SUS-3160
- Action Items
Plans for next phase
|PHASE 4 TEAM VISION|
Team Vision at a High Level:
- Electronics Project:
- Purchase all components under the
“electronics” label in the BOM
- Create required electronic system
- PID Controller
- SSR (Solid state relay)
- Power Switch
- LED indicator
- Power Cord
- Create required electronic system
- Test the system under different temperatures
- Draft diagram of the circuit
- Create user guide for the control system
- Purchasing / Metalworking
- Find exact measures for metal parts:
- Injection neck
- Heating cavity
- Body of the system (requirements):
- Estimated 36 ft of steel tubing
- Structural design of the enclosure
- Welding points VS elbows and Ts
- Support for melting cavity
- Compression System Integration Design
- Carjack into the structure
- Compression plate into melting cavity
- Find exact measures for metal parts:
- 3D Printing Project
- Print samples of the gutter
- Scaled to studied sizings
- Test integrity of the assembly in chains
- Design review by team
- Fabricate 1:1 scale model
Personal 3 Week Plans
- Pierce Scroggins - Scroggins Three-Week Plan.
- Adam Santagata - Adam Santagata Three-Week Plan.
- Kyle Appleman - Appleman Three-Week Plan.
- Vikas Patel - Patel Three-Week Plan.