Pecan ShellerMockup Review

Green A

Step 1A: Feeding

Feeding and cracking are simultaneous processes

Loading rate is limited by the time constraint of the cracker (6 seconds/pecan)

Proposed method: vibratory bowl feeder

Step 1B: Kinetic Cracking

26 pecans/minute in experiment by unskilled user

Rotating cylinder cracks the nut tips and shatters the shell

Anvil automatically adjusts to any size nut

Step 2: Shelling

Industry contacts have emphasized that shelling is the main problem

Need to maximize ratio of perfectly halved pecans to pieced pecans

Step 3: Separating

Must separate shell, packing material, and 2 kernel halves

Pieces are low value: used in baking and confectionary

Halves are high value: used in candy and sold on their own

Critical Module: Shelling

Figure 1. Distribution of Time to Process 10 Pounds or 250 Pecans

6%

91%

3%

Feeding andCracking

Shelling

Separating

Evaluation of Shelling Concepts

By Hand Rate

26/min

Shelled

100%

(except those unshelled by cracker – if any)

Halves

100%

(except those broken by cracker – if any)

Pro

Highest yield

Con

Incredibly Slow

Dollar Yield

1.04 lb/min

$8.32/min

Evaluation of Shelling Concepts

Shaking Rate

40/min

Shelled

100% (drill nut)

70% (without)

Halves

5% (drill nut)

75% (without)

Pro

Fast but damages halves with drill nut

Con

Difficult to reproduce motion, not FIFO

Dollar Yield

1.6 lb/min

$12.80/min

Evaluation of Shelling Concepts

Tumbling Rate

0.2/min

Shelled

20%

Halves

100%

Movie Pro

Didn’t crush halves

Con

Ineffectual, not FIFO

Dollar Yield

0.008 lb/min

$0.06/min

Evaluation of Shelling Concepts

Air Flow Rate

0.25/min

Shelled

10%

Halves

100%

Pro

Promising: used in industry on large-scale

Con

Cannot be the singular shelling process

Dollar Yield

0.01 lb/min

$0.08/min

Working Concept

Shear Rollers– Cracked pecans

dragged along plate by gear teeth

– Turning of gears shears off shell

– Spring mounted base soft enough to avoid crushing meat

Working Concept

Mechanical Shearing

Rate

1/min

Shelled

>5%

Halves

0%

Pro

Room for changes, optimization

Con

Ineffectual, grinds nuts

Dollar Yield

Small