Team Vision for System-Level Design PhaseIt was the goal of the team to decide on the overall design of the plastic melting and molding machine. To do this, the machine design must be broken down into sub-functions of the machine, and design components to satisfy the sub-functions individually. This is to be accomplished in the Functional Decomposition and Concept Selection sections. Benchmarking, a Morphological Table, and a Pugh Chart will be the tools used to compare the various proposed solutions. A visit to HARBEC Inc. (a local plastic molding plant in Rochester, NY) will help us to develop a solution to some or all of the sub-functions.
The team went through the process of Functional Decomposition and decided that the area that required the most design work was the heating and compression of the plastic. The visit to HARBEC was the primary inspiration for the solution to this problem and resulted in the current design that was selected. A System Architecture chart was created to further evaluate the selection.
Our notes from this meeting with Bob Bectold of HARBEC Inc. can be found here.
The working Functional Decomposition can be found here and will be maintained by Vikas Patel.
Feasibility: Economical, Market Analysis
Feasibility: Environmental, Water Quality Analysis
A link to the environmental feasibility research can be seen here.
All three studies looked at the effects of temperature and storage time on the material migration from the PET bottle to the water.
Results of each study indicated that during short sun-light exposure times, the PET-stored water quality barely changes. However, high temperature and CO2 presence increased the release of formaldehyde and acetaldehyde from the PET bottle to the water. A breakdown of each study is noted in the research document provided.
Feasibility: Prototyping, Analysis, Simulation
A link to the working melting feasibility spreadsheet can be seen here
Morphological Chart and Concept Selection
Concept DevelopmentFollowing the completion of the Pugh chart and concept selection, multiple possible concept solutions were generated. Short descriptions can be seen below and sketches of the concepts can be seen here.
PracticalThis possible solution would be a melting and molding process that is the best fit to solve our problem statement.The design would include middle of the road elements to sufficiently accomplish the goal.
EconomicalThe economical solution would require less complex elements to be economically feasible for implementation in El Sauce, Nicaragua.
IdealThe Ideal solution to our problem statement uses the top of the line elements as well as multiple elements for each sub function. Although this would be the most expensive solution, there would be the most safeguards for each sub function when in use.
Precious PlasticsThis possible solution uses elements that are the most similar to the small scale plastic recycling machinery shown on preciousplastics.com
Complex Mold (Precious Plastics Design)This Possible solution heats and melts the plastic chips inside the mold. The rest of the equipment setup is similar to the precious plastics example.
A complete file of the Pugh charts can be found here.
Based on our Pugh Chart analysis, we determined that the Complex Mold solution is the most feasible. It has some of the best system controls and is a reasonable and practical solution to our problem that we will be able to produce.
System InputsThe three inputs for our design include energy, plastic, and information. Energy input consists of power supplied from the grid which is 120 volts AC. The plastic input is the plastic chips that are meant to be upcycled. The information input consists of any human information interactions required to run the melting and molding process successfully.
The energy input's main use is in the heating process to melt the plastic. The plastic input is required to have a material input that is to be melted and molded. The information input serves the purposes of controlling the internal mold temperature through a manual dial and applying the compression force on the mold through a mechanical device.
Failure ModesSome potential failures modes of this system could include:
- Melting plastic timing
- Melting temperature regulation
- Applying insufficient compression forces
- Product damage during extraction
- Product deformation from insufficient cooling time
- Personal injury from operation
- Equipment wear from regular use
Designs and Flowcharts
New risksThe new risks that have been discovered through the system design phase include:
- Unable to achieve proper plastic melting temperatures
- Unable to achieve required compression forces for molding
- Damage to product when extracting from mold
- Low equipment life from repeated use
A working Risk Assessment file can be found here.
Three of our current risks have an importance of 9 and are detailed below.
- R2 states that the heater could break down and malfunction. This component is crucial to the melting of plastic and needed for the reforming of plastic. Without the heater element, the shape of plastic can only be altered with high compressive forces. This risk can be mitigated by repeatidly testing the heating element prior to installation
- R3 states that there would be inconsistent temperature regulation in the plastic melter. This would yield plastic that heats and melts differently in various parts of the mold. While some plastic could melt fully and eventually burn, other areas may not melt completly. This risk can be mitigated by measuring temperature gradients in different regions of melter durring testing of prototype designs. Temperature gradients can be used to redesign areas of the melter.
- R8 states that there are insufficient funds to purchase all the required design materials. This risk can be mitigated by searching multiple vendors and comparing prices to find the lowest priced items.
Four of our current risks have an importance of 6 and are detailed below.
- R5 states that we are unable to fill the mold using the plastic melting process. The ease of filling a mold with molten plastic is dependent on the viscosity and in turn the temperature of the heated plastic. To avoid this risk we consulted with HARBEC Plastics on proper plastic molding techniques. To mitigate this risk, the plastic can be melted while inside the mold, in order to eliminate the need to transfer the molten plastic into a mold.
- R7 states that the syatem inconsistantely produced the plastic product. This risk can be mitigated by measuring the dimensional variation between products and adjusting the molds accordingly
- R10 states that there are no facilities for us to safely test a moderately large furnace. Testing prototypes is a cruical aspect to designing a complex piece of equipment. This risk can be mitigated by locating useable lab on campus with a proper ventilation system
- R13 states that the initial benchmarking machines require salvaged items that may be difficult to acquire. Being that this design is intended for El Sauce, Nicaragua, the production costs of the equipment need to be relatively low in order to be econimically feasable. This risk can be mitigated by salvaging parts from old, free, or cheap apliances.
Design Review Materials
Plans for next phase
Personal 3 Week Plans
- Pierce Scroggins - Scroggins Three-Week Plan.
- Kyle Appleman - Appleman Three-Week Plan.
- Vikas Patel - Patel Three-Week Plan.
- Adam Santagata - Santagata Three-Week Plan.
- Ignacio Martos - Phase Plan