P15482: Breadfruit Shredder Brittany Griffin, Samantha Huselstein, Andrew Beckmann, Patrick Connolly, Alan Kryszak
Overview ● Background ● Concept Summary ● Final Design ● Testing ● Results and Recommendations
What is a Breadfruit? ● Nutrient rich tropical fruit o High in Carbohydrates, dietary fiber, Vitamin C, Potassium ● Member of the fig family ● Starchy, similar to a potato ● Common Haitian preparations: o Fufu* (similar to mashed potatoes) o Frying (similar to fried green plantains) o Boiled
Helping Haitian Farmers ● KGPB Farmers identified breadfruit as one the the most wasted agricultural products in the area ● Short shelf life (1-3 days) ● Summer harvest season ● Hard to transport, store, and preserve ● Solution must be low cost and have no energy cost Converting breadfruit into flour addresses these problems and it was our team’s challenge to do it at low cost and low energy!
Project Goals ● Flour producing process = 3 parts o Shredding o Drying o Grinding ● Working prototype(s) that shreds breadfruit to be dried and grinds dried breadfruit pieces
Customer Requirements of Highest Importance Category Requirement Feasibility Uses available resources Feasibility Minimizes water usage Cost No energy cost Cost Low maintenance cost Ease of Use Can be used by adult breadfruit farmer Safety Provides barrier to hazardous parts Safety Does not contaminate food Profit Provides flour that can be used to make fufu
Architecture
Functional Decomp
Concept Generation Brainstorming Benchmarking
Concept Selection Pugh Analysis Selection Criteria ● Doesn’t use electricity ● Available in Haiti Bonus: Peels and cores breadfruit ● Easy to maintain/sharpen ● Effort required to operate ● Easy to understand ● Within budget
Feasibility Al Prototype ● Prototyping Question: Will our blade design work? o Created Mock-up blades from Al Mill tooling Also used horizontal mill tooling Results: Works well! 3 teeth seemed to work o better and would be easier to manufacture ● Deflection of Plastic Blades Question: Can we save cost by using plastic o blades? Results: We are not sure if they will be o strong enough. Would be a huge risk. Plastic blade deflection
Feasibility Shear pin calculations ● Question: Can we have a shear pin that will allow breadfruit to be shredded but protect the blades? ● Results: Yes, but we needed to increase the size of the pin and get more durable keys for the shafts Fatigue Life of Shafts Question: Will this need to be repaired in Haiti? Results: Safety factor of ~300, therefore, will not break within its useful life
And then there was one... ● Cost Analysis o Shredder budget ~ $600 o Grinder budget ~ $325 o Problems: shipping cost not accounted for, no room for error in manufacturing, risky grinder design, rollers would need to be replaced for grinder design (before shipping to Haiti), does not include hopper or stand ● Project Plan Photo Credit: UMICH Breadfruit Grinder Team o Over 100 parts to be made for shredder alone! o No time to build 2 machines in one semester
Final Design Final Design
Final Design Details ● Materials o Non-corrosive, highly durable ● Shear Pin o Fail-safe, protect blades and shaft keys ● Hopper o Provide safety, holds up to 6 breadfruit (peeled and cored) ● Stand o Comfortable for person around average Haitian height o Braced for stability o Holds 5 gal bucket o Can place cinder blocks to help hold it down
Design Changes/Difficulties Design Difficulties Design Changes ● Bending Guards ● Shear Pin Diameter Accurately ● Hopper Size ● Tight Clearance ● Stand Cross Braces Between Blades ● Key stock Material ● Properly Building ● Shaft Size for Blades Welded Parts
Other Problems Overcome...
Testing ● Shear Pin Test ● Interference ● Operating Metrics ● Assembly Timing ● Shredder Yield
Shear Pin Results Conclusion: The result of the shear pin test above shows that all shear pins sheared at values less than the T high value of 11,697 psi. Therefore no damage will be done to the system and only the shear pin will need to be replaced.
Interference Results ● Interference testing was performed throughout the build process. ● All parts were measured to meet Drawing Specifications. ● Blades and spacers were precision ground in pairs to ensure no interference between parallel shafts. Blades have .003” Clearance (Less ● than a piece of paper!)
Operation Metrics Results Conclusions : All operating metrics met their target values. Average of ~71.2 breadfruit per hour. Cleaning met the marginal time. Recommendations: ● Cut breadfruit into eighths instead of quarters. (Does not need re-adjusting in hopper to get caught in blades) ● Feeding shreds through twice will make smaller more uniform shreds (will save on drying time) Use tube/bottle brush instead of toothbrush (Plastic of toothbrush was shaved off by blades) ● ● Look into sending a squirt bottle for faster cleaning
Assembly Timing Results Conclusion: All set up, disassemble, and reassemble times were below target values. Moving entire assembly can be done in a quick and efficient manner. Recommendations: Redo test with more people to make sure we continuously meet specs
Shredder Yield Results Conclusion: Shredder Yielded ~98.3% of input breadfruit by weight. Almost all of breadfruit was shredded leaving on only 1.7% of breadfruit left in shredder. Recommendation: By running the shredder in reverse for 3-4 turns, the remaining breadfruit can be retrieved and can be reprocessed through the blades.
Project Evaluation
Project Plan versus Actual ● Task tracker was used to determine when tasks needed to be completed versus when they were actually completed. ● Tasks were completed on average .13 and .75 days in advance for MSD I and MSD II respectively.
Budget Evaluation Proposed Budget vs Actual Budget Amount Vendor Description Charged Speedy Metals Misc. parts $360.48 McMaster Misc. parts $163.39 BDI Express Misc. parts $95.43 Klein Steel Angle Iron $41.10 ePlastics Black acetal sheet $76.98 Curbell Polycarbonate sheet $30.00 Lowe’s Paint $27.50 Wegmans Breadfruit $96.58 Remaining Balance $108.54 Total Spent $891.46
Recommendations for Future In Haiti: ● Teach about shear pin function ● Teach about hopper function (in regards to safety) ● Collect Feedback from Farmers Shredder specific - What do you like? What do you not like? How o often do you use the shredder? Is flour being used by KGPB farmers? o Does your family use breadfruit flour? o Are the women selling the flour in the market? o Is there a part of the flour process that could be better? o
Recommendations for Future If new shredder is needed: ● For 2nd iteration of MSD ● Easier to manufacture ● Look into cheaper materials to use o More thorough analysis on plastics ● Look into using less/lighter material ● Ability to use with manual AND motor power ● Implement any other design changes based on feedback from KGPB farmers
What we learned Feedback helps ● What we would do differently: Peer reviews and +/delta o ● Handle to pick up shredder ● Risk Assessment Paint sooner (time to cure) ● Identifying where things can o ● Change finger bolts to go wrong helped us avoid countersunk for better locating problems ● Turn shaft nuts from scratch ● Communication ● GroupMe communication sooner Work Breakdown Structure o (beginning of MSDI) GroupMe o ● Check drawings more closely ● Documentation ● More than 1 person in charge of Machining skills ● CAD ● Problem solving skills ● Better use of our WBS ● Design processes/skills ● Presentation skills
MSD Improvements ● Better use of MSD I class time o Lectures online and in class were repetitive ● MSD I storage space ● More experts in the machine shop ● Weekend hours for the machine shop ● More emphasis on prototyping ● Better matching of skills to project ● More team-to-team feedback
Photo Credit: Phil Medalie (Imagine RIT Photos), Questions? Rob Stevens (Haiti pictures), and MSD Team
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