Initial Concept Generation
Initial Benchmarking and Concept Generation
BenchmarkingInitial benchmarking activities included researching cassava processing machines presently used in West Africa and testing products available in the United States. Information was gathered on cassava machines, both manual and motorized, as well as commercial manufacturing equipment used in the production of various grains. The team's intention was to design a unit for household use and as a result, consumer kitchen products were deemed most appropriate for use in benchmarking and testing.
The two most effective products tested in the benchmarking phase are shown here, an apple peeler and a food mill. Both apparatus' were tested using yams (cassavas were unavailable at the time).
Food Mill: Roots (or pieces of roots) are added to the mill. Turning of the handle forces the material through a small grate creating a grainy paste.
Massive Roller Assembly - This complex design combines peeling and grating into one unit. The root is driven by rollers along the central axis of the machine. It it rotates while driven and is cleaned, peeled and grated in one pass.Issues: Complex to manufacture, assemble and maintain.
Cinnamon Sticks - Design involves multiple abrasive rollers which peel cassava. Issues - Design only peels. Safety concerns.
Off Center Grinding - Root is peeled as it is rotated. Issues - Only peels. Could produce excessive waste/scrap.
Corer - Root is forced through a circular blade which cuts a large core out (removing the outer layer of skin and most likely a large amount of flesh. Issues: Safety concerns. Excessive waste. Only peels.
Juicer - Peeled cassavas are placed in hopper and grated to a grain size determined by the size of the blades on the cutting disc. Device separates pulp (flesh) from starchy liquid (by-product). Issues - Only grates.
Concept Scoring - Matrix provides an overview of the pros and cons of each design, comparing each to the apple peeler and food mill. The designs with the highest scores were used to develop the final concept. The final concept listed, 'Best Damn Cassava Grater Ever' is shown below.
Best Damn Cassava Grater Ever/Selected Concept - This design incorporates both peeling and grating functions. The peeling arm is similar in design to that on the apple peeler (benchmarking) and the grating aspect is completed through the use of a fine grater disc (similar to those found in food mills and food processors). Cassavas are fed into the unit through a feeding tube on the protective cover. While the user turns a crank handle causing the disc and blade arm to rotate, the gravity-fed cassavas contact the cutting surfaces; the peel is removed and the cassava is grated to a fine grain which is deposited into a container on the underside of the disc.
Concept Review and Action Items
A concept review with the customer and engineering professors and students resulted in the following considerations for design modifications as well as action items to be addressed prior to the follow-up design review.
- Ideas and Issues to Consider:
-Off-center grating with center peeling (Grating on central axis is not effective)
-Remove radial disc from top (rather than from front/side)
-Can design be adopted to run on a motor (rather than manual operation)?
-Where does the skin go? Must be separated from flesh before grating.
-Reconsider the use of bevel gears (very expensive), find other alternatives. Also, gears could get jammed from pieces of cassava.
-Complexity of design increses cost and results in difficult maintenance and repairs
-Stainless steel is expensive but will last a long time and will limit corrosion