Cashew Processing Flow Chart
A flow chart of cashew processing showing the input, output and machine at each stage — from raw cashew nut in to sealed kernel out.
A cashew processing flow chart maps the material flow from raw cashew nut to packed kernel. At each stage there is an input, a transformation and an output: raw nuts → graded nuts → steamed nuts → shelled kernels + shell → dried kernels → peeled kernels → graded/sorted kernels → vacuum-packed kernels. Shell exits to the burner for energy and testa is removed at peeling. The table below is the flow chart in tabular form.
Stage-by-stage: parameters and equipment
Each stage prepares material for the next. Missing or poorly executed steps create problems downstream that no amount of quality equipment can fix later.
1 · Reception & storage
raw nuts arrive at 8–10% moisture mixed with harvest debris. Store at 7–8% moisture: higher risks mould, lower makes shells brittle. Hold 15–30 days of raw-material buffer so the line is never starved of feedstock.
2 · Cleaning & preliminary grading
multi-deck vibrating screens remove leaves, twigs and stones and sort by size. 500–2,000 kg/h depending on model, 2–5 HP. Size uniformity drives every downstream result: shell mixed sizes together and you either under-process the large nuts or break the small ones.
3 · Conditioning (steaming)
high-pressure steam at 3–4 bar for 20–25 minutes, in batches of 300, 600, 800 or 1,000 kg depending on the model. Softens the shell and partially liquefies the CNSL. Lifts kernel recovery from about 75% to 85–90% and reduces shelling-machine wear. Nuts then cool and rest 12–24 hours before cutting — a nut taken straight from the steamer cuts worse than one that has stabilised. Alternative: roasting drums, common in African facilities, which burn off CNSL but need tight temperature control.
4 · Shelling (cutting)
calibrated blades make two precise cuts without reaching kernel depth, so the shell splits away intact. Whole-kernel recovery 85–90%, roughly 2–3 HP per head. Shelling capacity must match dryer capacity or it becomes the bottleneck. Good machines include CNSL collection trays, turning a disposal problem into a revenue stream.
5 · Borma drying
the borma oven, Stage 08. Kernels enter at 9–12% moisture and leave at 3–4%, on a 13–14 hour batch cycle. Chambers run 0.5, 1, 1.5, 2 and 4.5 tonnes per batch. Size the dryer to shelling output: a line shelling 300 kg/h over an 8-hour shift yields ~2,400 kg of wet kernels, so plan a 2 T or 4.5 T chamber.
6 · Kernel humidification
Stage 09, a separate room from the borma dryer. Dried kernels at 3–4% are deliberately brought back to 5–6% surface moisture before peeling. Counter-intuitive but essential: too dry and kernels chip, too wet and the testa clings. Cycles run 5–6 hours on 0.5 T and 3–5 hours on 2–4.5 T, on the same chamber platform as the dryer at half the fan power.
7 · Peeling
rotating drums plus compressed air lift the loosened testa clear. One head runs 120–180 kg/h and four heads 420–480 kg/h, each paired with its own compressor from 30 to 100 HP. Target 80–85% white wholes and 80–90% peel on the first pass, with un-peeled kernels recirculated rather than forced.
8 · Kernel grading
roller classify machines separate W180 through W450 and the broken grades — 150–180 kg/h on 12 axes up to 420–540 kg/h on 36, with a dedicated broken-kernel sorter at 150–200 kg/h. Misgrading costs money in both directions, so this is not the stage to under-specify.
9 · Colour sorting
cameras and air ejectors remove scorch, specks and foreign material after roller grading. Chute sorters handle 500–1,000 kg/h; belt sorters with 18 cameras and 252 channels run 1–3 t/h. This is the last check before packing, not a repair stage.
10 · Packing and metal detection
a kernel sorting line at 1,000–1,500 kg/h feeds auto-weighing vacuum packers running 50–70 packs/h on a 45-second cycle with two operators. A conveyor metal detector catches ferrous, non-ferrous and stainless contamination down to 1–2 mm before the lot leaves the building.
TTQ works to an average of 35 kg/h per cutting head on Size A. A 10-head line therefore runs about 350 kg/h (410 kg/h on Size A+), and a 16-head line about 560 kg/h. Knife-configured machines run a little higher per station — a 16-knife machine reaches about 700 kg/h on Size A. Older published figures of 60–80 kg/h for a single head do not reflect this standard and have been corrected. All capacities are quoted per 8-hour shift.
| Stage | Input | Output | Machine |
|---|---|---|---|
| 1. Calibration | Raw cashew nuts | Sized nuts | Raw-nut size sorter |
| 2. Steaming | Sized nuts | Softened nuts | Steaming machine + boiler |
| 3. Shelling (cutting) | Softened nuts | Kernels + shell | Shelling / cutting line |
| 4. Borma drying | Shelled kernels at 9–12% | Dried kernels at 3–4% | Borma dryer |
| 5. Humidification | Dried kernels | Kernels at 5–6% surface | Humidifier room |
| 6. Peeling | Humidified kernels | Peeled kernels + testa | Peeling machine + compressor |
| 7. Grading + colour sorting | Peeled kernels | Graded, sorted kernels | Classify machine + colour sorter |
| 8. Packing + metal detection | Graded kernels | Sealed export lots | Vacuum line + metal detector |
Shell from stage 3 is routed to the shell burner for process heat. Stages 4 and 5 are separate machines in separate rooms — the borma dryer takes moisture out, the humidifier puts a controlled amount back.
For the narrative version, see the step-by-step guide; for the full process overview, see cashew nut processing.
The process, drawn
The eight core stages
Raw cashew nut in at one end, packed export kernel out at the other. Moisture is the thread: every stage either takes it out or puts a controlled amount back.
Capacities and cycles are Size A basis, per 8-hour shift. Stages 04 and 05 are separate machines in separate rooms — the borma oven dries, the humidifier puts moisture back.
Where the raw nut actually goes
One tonne of RCN leaves the plant as three streams, not one. The kernel pays the wages; the shell pays the fuel bill.
The testa is the thin brown skin taken off at peeling. CNSL comes from the SHELL, not from the testa or the husk — a distinction worth holding onto when reading supplier literature.
The shell energy loop
The cleanest economics on the site: the waste stream from stage 03 comes back as the heat for stages 02 and 04.
The same TTQ boiler range fires cashew shell, wood chips or pellets. Note the dryer is heated by electrical coils or by boiler steam through heat-transfer coils — the shell burner fires the boiler and the roasting machine, not the dryer directly.
Frequently asked questions
What is the cashew processing flow?
Where does the shell go?
Related reading & machines
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