Bench-mounted. One nut at a time.
CASHEW MACHINE:
ERGONOMIC REDESIGN
Product Design for Social Impact
- Team Members
- 4
- Timeline
- 3 weeks
- My Role
- End-to-end: Research to Prototype
- Tools
- Figma, Illustrator, Blender, Premiere Pro
Introduction
The process of extracting cashew is a labour-intensive and hazardous process. Despite advancements in technology, a significant portion of this process still relies on manual labour. How might we enable workers to safely handle and process cashews without compromising their productivity?
Cashew Processing Journey
AI Generated
Tree Maturation
Cashew trees flower in late winter. As the juicy cashew apple develops, the true seed grows externally at its base encased in a tough, hazardous double shell.
AI Generated
Ground Collection
Ripe fruits drop naturally to the orchard floor. Workers hand-gather fallen apples and twist off the raw nut in shell on-site before insects or rot set in.
AI Generated
Sun Drying
Freshly harvested raw nuts are spread across concrete open-air drying yards for 2–3 days, bringing moisture down to ~8% for stable year-round storage.
AI Generated
Steam Conditioning
Before cracking, raw nuts are treated in high-pressure steam boilers. This softens the leathery outer shell and loosens the inner edible kernel from the shell wall.
AI Generated
Manual Shelling & CNSL Contact
Workers crack the outer shell by hand. Rupturing the shell releases corrosive Cashew Nut Shell Liquid (CNSL), resulting in painful dermatitis and permanent chemical scarring.
AI Generated
Whole Kernel Extraction
Intact whole white kernels fetch the highest export premium; broken pieces lose up to 50% value. This piece-rate pressure pushes workers to avoid gloves for speed.
Understanding the landscape
KEY INSIGHT
Existing automated machinery operates at only ~70% accuracy, making manual intervention essential for quality control and kernel extraction.
KEY INSIGHT
Due to exposure to Cashew Nutshell Liquid (CNSL), workers often resort to using ash on their fingers as a protective measure, highlighting the lack of effective and accessible safety solutions.
KEY INSIGHT
Workers are compensated based on the weight of processed nuts rather than time, incentivising speed and discouraging the use of protective gear that might reduce efficiency.
Cracks in the industry
Labour Exploitation
User Research
Stakeholders Interview
What we heard
FACTORY OWNER
Young workers are leaving for bigger cities. Automation became survival, not a choice.
FACTORY OWNER
Machines are fast but blunt: 30% of cashews break. Hands were slow but careful.
FACTORY OWNER
Whole cashews sell at a premium, so breakage is a hidden tax.
FACTORY OWNER
Older workers find complex machines intimidating.
FACTORY SUPERVISOR
Scooping and hand-cutting are the riskiest jobs. Burns and cuts are accepted as part of the work.
FACTORY SUPERVISOR
Long hours of seated scooping and peeling strain the neck, shoulders and back.
FACTORY SUPERVISOR
Some steps are automated, but most still depend on hands.
FACTORY WORKER
Workers treat pain and burns with painkillers, sprays and oil.
FACTORY WORKER
They pick tools that are easy over fast, if fast means more effort.
FACTORY WORKER
Every tool belongs to the factory, not the worker.
FACTORY WORKER
The blade is the part workers fear most.
FARMER
Cashews sell fresh (geela kaju) or dried, for different buyers.
FARMER
Stored nuts keep factories working all year, beyond the harvest.
FARMER
Flowers in late Jan, falls by mid-March, then sun-dried and sent for processing.
The NUTS & bolts
Five tools already doing this work, from a pair of shears to a motorised line. Everything that follows is measured against them.
Hand shears. Cheapest tool on the floor.
Standing frame, full-length lever arm.
Foot-powered. Both hands stay free.
Motorised, continuous-feed, high volume.
Identifying ergonomic Issues
Task & Posture Analysis
We used RULA (Rapid Upper Limb Assessment), REBA (Rapid Entire Body Assessment), QEC (Quick Exposure Check) and Strain Index (SI) assessments to evaluate the physical strain and ergonomic risks faced by workers during their tasks.
The RULA scores for hand-cutting and scooping tasks showed a moderate-to-high risk, the REBA score was 10 (very high risk), the SI scores were above 10 (hazardous risk for upper-limb disorders) and QEC scores indicated high exposure which can lead to injuries.
According to our calculations
Cracking the solution
Design Requirements
Concept Development
We built a 1:3 model of the final concept.
Final Concept
The final mechanism brings deshelling and scooping together into a single, manually operated tool eliminating repeated hand transfers, shielding workers from CNSL contact, and optimising mechanical leverage without requiring electricity.
Predicted Impact
A hand-turned drive wheel and pulley merge cutting and scooping into one continuous motion, replacing the hunched pinch-grip with a rotational movement and removing all hand contact with the shelling process. Posture assessment of the proposed design predicts a 60% lower overall REBA score and roughly 90% less wrist strain on both hands. These figures are calculated from the design's working posture, not yet measured with workers. No CNSL exposure, no electricity and no replacement of manual labour — which is what makes it viable on an existing factory floor.
