Preliminary Detailed Design
Team Vision for Preliminary Detailed Design PhaseThe goal of the team during this phase was to finalize the design of the plastic melter. The team planned on working through the sub-systems, designing the different components. We planned to outline all of the necessary components to build the melter and start purchasing parts for testing, especially the electrical components.
Working through these tasks the team was able to get an electrical diagram and a 3D model started to visualize what the system and to decide what parts will need to be ordered. Some feasibility testing was performed during this phase, electrical testing on the current device and hand calculations for heat transfer and compression analysis. After some of the testing electrical components were ordered so more testing can be performed. Also, the heater supplier was contacted for more information.
A call was set up with a previous group member (Iggy from P18433) to go over some questions the team had. Along with finally contacting the Enlace Project contact, Kellan, and having a phone call (notes can be found here).
The risk assessments and the Bill of Materials were both updated as well during this phase to gather necessary components and reassess the risks associated with the melter.
Feasibility: Prototyping, Analysis, SimulationDuring this phase feasibility analysis' were performed as well as some electrical testing.
Heat Transfer AnalysisThis goal of this analysis is to calculate how much heat is required by our system to melt a bed of plastic chips, assuming there is insulation surrounding the heaters. The strip heaters currently in the system are rated to output 300 Watts each, for a total of 1800 Watts for the six strip heaters combined.
Electrical TestingThe electrical engineers on the team (Deryck and Nick) were able to remove 3 of the heaters from the current melter to see if removing some of the heaters would allow the other 3 heaters to increase their temperature. The results showed that there was no change in this test than in the original melter test. The heaters got up to the same temperatures even with less heaters used in the system.
This goal of this analysis is to calculate how much force and/or pressure is required by our system to compress the bed of plastic chips into a flat sheet. Some rough calculations were found and used from the Precious Plastics website. Based of the calculations, the car jack selected by the team will be able to provide enough compression as it is rated for at least a ton and the analysis showed that the plastic only needs to be compressed by 0.852 tons. We purchased a carjack rated to 1.5 tons which should apply plenty of compression to form the plastic.
Drawings, Schematics, Flow Charts, Simulations
During this phase the electrical engineers on the team worked together to asses the current state of the electrical components of the current device. Then working off the current state and considering the changes the team would like to make to the melter they were able to design a schematic that will be used to wire the electrical components in the remodeled device.
A working copy of the electrical schematic can be found here.
3D ModelDuring this phase the mechanical engineers on the team worked together to asses the current model of the melter. Then working off the current model from the previous team and considering the changes the team would like to make to the device, we were able to design a 3D model that will be used to figure out which parts need to be purchased and how to assembly the device.
- For creating and working on the models the team chose to use OnShape, an online CAD system that allows multiple people to modify the models at the same time, our 3D model can be found here.
Location to Test Melter
The team ran into the issue of finding a permanent home for the melter since it requires a 208V 3 phase outlet and a ventilated area for testing. Previously, the team tested in the Plastic's lab in a different college but does not have the ability to gain full access to the lab which is not suitable for regularly testing. The machine shop in Gleason estimated the cost for installing the correct outlet in the ventilated welding area for $600 which is high for MSD. The team also looked into using the Material Science lab in Gleason but concluded that the space does not fit our needs. MSD is currently looking into repairing an existing fan on the design floor that would provide the team and future MSD teams the correct outlet and ventilation. Right now, this roadblock is only minor but could escalate quickly if the team is unable to test safely during future phases.
The current compression system on the melter is a car jack oriented to move downwards when cranked. P18433 was very concerned of the safety of this design and warned that the top mold could randomly collapse. The team continued to brainstorm alternative options during this phase.
Linear Actuators Linear actuators was considered because of the "up" and "down" movement which would move the bottom plate of the mold up and compress the plastic as it's melting. The issues with the actuators includes the high cost (would need two to support the mold), unsure of how to attach them to the mold, and the continuous running of the motors to keep the mold in place during the entire cycle. The team also was hesitant to use this option since the actuators would be near high temperatures from the heaters and the risk of them overheating or decreasing the lifetime of the actuators were too high.
The team also considered designing a similar spring system that Dave Hakkens, founder of Precious Plastics, created to compress recycled plastic. The systems uses a single photovoltaic panel for power and uses a stiff spring, a mold, and a crank to compress the plastic into a useable product. A video of the compression melter can be found here. In order for the team to build a similar system, the current frame of the melter could not be used which is an important component our team wants to reuse for the new melter.
New Car Jack
The team analyzed P18433's melter and their reasoning for choosing a jack for the compression system. A concern the team has is the ergonomics of cranking the manual jack since it is a repetitive motion that could cause issues to the operator. During the construction of the melter, the team will perform tests operating the jack and will add a gearbox if necessary to avoid strain on the operator. The team's decision to replace the jack and attach it to the bottom mold to allow upward movement compression instead of the current placement was finalized after speaking with a member from P18433. The car jack is a low cost and sturdy solution that will meet the compression needs of the system, it is also easily replaced if that is ever necessary.
Bill of Material (BOM)
During this phase the team compiled a list of items (the Bill of Materials) that need to be purchased in order to build the melter device. Currently, The BOM is combined with the Budget and is up to date, but may need to be further changed as the design is finalized. The BOM and the Budget will be two separate documents when finalized.
The working copy of the BOM can be found here
The team experienced several roadblocks during this phase which led to re-evaluating the risks from the Systems Design Phase. The team's high risks this phase relate to the electrical system and compression system which will ultimately effect the ability to form a sheet for our customers.
A working copy of the team's risk management can be found here.
The team developed test procedures specifying the type of data to be collected, instrumentation, procedures and personnel who will conduct the tests. This process is crucial to verify that the melter is meeting all ERs developed during Phase 1.
- T1-Temperature and Heat Testing
- T2-Machine Dimensions
- T3-Compression Testing
- T6-Product Quality
The Test Procedures that will be performed to verify the melter meets the ER's.
A Test Plan Template was created to use during testing.
All Test Procedures correlate to an ER and can be found here
The Test Procedures and Test Plan Template were adapted from P18433.
Design Review MaterialsInclude links to:
Plans for Next Phase
List of items to complete:
- Continue electrical testing of current system and add in new electronics as they arrive
- Continue prototyping: install and test new jack
- Finalize 3D model and designs
- Begin 2D drawings of the system for documentation