How to Design a Cashew Cutting Line
Most cashew processing lines are undersized, oversized, or wrongly configured — not because of budget, but because the design starts from the wrong assumption. The common mistake is treating the cutting stage as a single throughput problem: buy a machine rated at X kg/hr, done. In reality, cashew cutting is a per-grade problem. Nuts arriving at the cutting stage have already been graded by size. Each grade requires its own dedicated machine, calibrated to the correct blade gap for that nut diameter. Running mixed grades through a single machine shatters small nuts or fails to open large ones.
This guide walks through the exact methodology OUTTURN uses to size cutting lines for new processing plants — from a blank sheet to a complete machine specification with utilisation rates and redundancy built in.
What you need before starting: Your target daily RCN input volume (kg/day), your working shift hours, and the origin of your raw cashew nuts. Everything else is calculated from these three inputs.
STEP 1 Establish Your Daily RCN Input and Shift Hours
Start with the raw numbers — not the kernel output target, but the raw cashew nut input. Cutting line design is based on RCN throughput because that is what the machines process. Kernel output varies by origin and grade and is downstream of the cutting stage.
Key inputs to confirm:
- Daily RCN input in kg/day — the total steamed RCN volume your plant will process in a single working day
- Working hours per shift — typically 8 hours for a single-shift operation
- Number of shifts per day — single shift is standard; double shift is possible but requires redundancy planning
Convert to hourly throughput:
| Plant Scale | Daily RCN → Hourly Throughput (8hr shift) |
| Small plant | 400–800 kg/day → 50–100 kg/hr |
| Small-medium plant | 800–2,000 kg/day → 100–250 kg/hr |
| Medium plant | 2,000–8,000 kg/day → 250–1,000 kg/hr |
| Large plant | 8,000–20,000 kg/day → 1,000–2,500 kg/hr |
Important: Design your cutting line for your peak-season throughput, not your average. Cashew is a seasonal crop — your line must handle peak procurement volume without bottlenecking. Most plants undersize at design stage and then run machines above recommended utilisation during peak season.
STEP 2 Identify Your RCN Origin and Size Profile
The single most important variable in cutting line design is the size profile of your raw cashew nuts. Nuts from different origins have dramatically different size distributions — meaning the proportion of large, medium, and small nuts varies by country. This directly determines how many machines you need at each size grade.
Size grades in the cashew industry run from A+ (largest) to D (smallest). Each grade requires its own dedicated cutting machine calibrated to a specific blade gap. The table below shows the size distribution for the major cashew origins:
| Origin | A+ | A | B | C | D | Nuts/kg |
| Indonesia | 8% | 30% | 35% | 22% | 5% | ~165 |
| Cote d’Ivoire | 5% | 25% | 38% | 25% | 7% | ~185 |
| Ghana | 3% | 20% | 35% | 30% | 12% | ~195 |
| Nigeria | 3% | 18% | 32% | 32% | 15% | ~220 |
| Tanzania | 4% | 22% | 36% | 28% | 10% | ~200 |
| Guinea-Bissau | 6% | 28% | 36% | 24% | 6% | ~180 |
| Vietnam | 10% | 32% | 34% | 20% | 4% | ~158 |
| India | 4% | 20% | 33% | 30% | 13% | ~210 |
If your plant processes multiple origins across the season, design for the origin with the highest D-grade fraction — this is always the bottleneck grade because D-grade nuts are the slowest to cut and have the highest uncut rate.
STEP 3 Split Your Hourly Throughput by Size Grade
Multiply your total hourly RCN throughput by each grade’s percentage share. This gives you the kg/hr of each grade that needs to be processed separately.
Example — 500 kg/hr total throughput, Nigeria origin:
| Grade | Share | kg/hr (raw) | +10% buffer | Design target |
| A+ | 3% | 15 kg/hr | 1.5 kg/hr | 17 kg/hr |
| A | 18% | 90 kg/hr | 9 kg/hr | 99 kg/hr |
| B | 32% | 160 kg/hr | 16 kg/hr | 176 kg/hr |
| C | 32% | 160 kg/hr | 16 kg/hr | 176 kg/hr |
| D | 15% | 75 kg/hr | 7.5 kg/hr | 83 kg/hr |
| TOTAL | 100% | 500 kg/hr | 50 kg/hr | 550 kg/hr |
Why the 10% buffer matters: Machines don’t run at 100% rated capacity in real operating conditions. Nut feed irregularities, brief stoppages for blade checks, and moisture variation in steamed nuts all reduce effective throughput. The 10% operational buffer ensures your line hits its target volume even under normal operating variance.
STEP 4 Select the Right Machine Configuration Per Grade
Each grade stream now has a kg/hr design target. Match each target to the appropriate OUTTURN cutting machine configuration. OUTTURN machines run on a horizontal rotary mechanism — each additional head multiplies cutting capacity while the motor remains a constant 0.75 kW (1 HP) across all configurations.
| Config | Heads | Effective Capacity | Motor | Best Suited For |
| 2-Head | 2 | 40–80 kg/hr | 0.75 kW | A+ grade, very small streams |
| 4-Head | 4 | 120–200 kg/hr | 0.75 kW | A and B grades, small plants |
| 6-Head | 6 | 180–260 kg/hr | 0.75 kW | B and C grades, mid plants |
| 8-Head | 8 | 240–320 kg/hr | 0.75 kW | C and D grades, larger plants |
| 10-Head | 10 | 300–400 kg/hr | 0.75 kW | B/C/D grades, industrial scale |
| 12-Head | 12 | 360–480 kg/hr | 0.75 kW | High-volume B/C streams |
For each grade, divide the design target kg/hr by the effective capacity of your chosen machine. Round up to the next whole number — this gives you the minimum machine count for that grade. If the result shows a machine running above 95% utilisation, step up to the next configuration or add a second unit.
STEP 5 Calculate Machine Count and Flag Utilisation
Continuing the Nigeria 500 kg/hr example from Step 3, here is the full machine selection:
| Grade | Target kg/hr | Machine | Eff. Cap. | Units | Total Cap. | Utilisation |
| A+ | 17 kg/hr | 2-Head | 80 kg/hr | 1 | 80 kg/hr | 21% ✓ |
| A | 99 kg/hr | 4-Head | 200 kg/hr | 1 | 200 kg/hr | 50% ✓ |
| B | 176 kg/hr | 6-Head | 260 kg/hr | 1 | 260 kg/hr | 68% ✓ |
| C | 176 kg/hr | 8-Head | 320 kg/hr | 1 | 320 kg/hr | 55% ✓ |
| D | 83 kg/hr | 4-Head | 200 kg/hr | 1 | 200 kg/hr | 42% ✓ |
| TOTAL | 550 kg/hr | 5 machines | — | 5 units | — | All within range |
Utilisation guide:
- Under 40% — machine is oversized for this grade stream; consider downsizing
- 40–80% — ideal operating range with good headroom
- 80–95% — monitor closely; any volume spike pushes into over-utilisation
- Over 95% — upgrade to the next configuration or add a second unit
STEP 6 Plan Steam Drum Synchronisation
Cutting machines operate on steamed RCN — nuts that have been treated with steam for a specific duration to soften the shell and reduce CNSL spillage. The cutting line design is only complete when it is synchronised with steam drum capacity. A cutting line that outruns its steam supply is idle. A steam supply that outruns its cutting capacity produces over-steamed nuts that degrade kernel quality.
Key synchronisation principle:
Match your total cutting line throughput to the combined output rate of your steam drums. Steam drum capacity is typically expressed as kg per batch and batch cycle time in minutes.
| Steam Drum Size | Batch Capacity | Cycle Time |
| Small drum | 80–120 kg per batch | 25–30 minutes |
| Medium drum | 150–200 kg per batch | 25–30 minutes |
| Large drum | 250–400 kg per batch | 25–30 minutes |
For a 500 kg/hr cutting line, you need approximately 500 kg of steamed RCN available per hour. With a standard 30-minute steam cycle and 200 kg drums, you need at minimum 4–5 steam drums running in rotation to maintain continuous supply to the cutting machines without waiting periods.
Field note: In plants processing Nigeria or Ghana origin nuts — with their higher D-grade fraction — steam time is more critical than in Vietnam or Indonesia processing. Slightly over-steamed D-grade nuts cut more cleanly, but under-steamed D-grade nuts have the highest uncut rate of any grade. When in doubt, err toward adequate steam time for D-grade.
STEP 7 Document the Final Line Specification
Once all calculations are complete, document the cutting line specification in a format that can be shared with your supplier for quoting and with your plant engineer for layout planning. A complete cutting line specification includes:
- Total daily RCN input (kg/day) and shift hours
- RCN origin(s) and size profile used for design
- Per-grade throughput breakdown (kg/hr per grade)
- Machine configuration selected per grade with unit count
- Utilisation rate per machine
- Total installed cutting capacity (kg/hr)
- Steam drum count and synchronisation schedule
- Total motor load (number of machines × 0.75 kW per machine)
- Floor space requirement per machine (allow 1.5m × 1.0m per unit plus 0.8m operator access on feed side)
Use the OUTTURN Cutting Machine Design Calculator: The Design Calculator at cashew-technology.com automates Steps 3–5 of this guide. Enter your daily RCN volume, shift hours, and origin — the calculator outputs the full per-grade machine recommendation with utilisation rates. Use this guide to understand the methodology behind the calculator output.
Cutting Machine Design Calculator
Per-grade machine recommendation based on your RCN origin and daily capacity
Common Mistakes in Cashew Cutting Line Design
These are the most frequently encountered errors in cutting line design, in order of how often they occur at installation:
Mistake 1 — Designing for Average Throughput Instead of Peak
The cashew season is 3–4 months. Plants that design for average annual throughput are undersized during peak procurement and idle outside season. Always design for peak-season daily intake.
Mistake 2 — Running Mixed Grades Through a Single Machine
This is the most damaging operational error. A machine calibrated for B-grade will shatter D-grade nuts and fail to open A+ grade nuts cleanly. Pre-sorting by grade before the cutting stage is not optional — it is fundamental to achieving target whole kernel rates.
Mistake 3 — Ignoring Origin-Specific Size Profiles
A line designed for Indonesian nuts will be misconfigured for Nigerian nuts. The D-grade fraction alone changes from 5% to 15% between these origins — tripling the machine capacity required at the D-grade stream. If your plant sources from multiple origins, design for the most challenging profile.
Mistake 4 — No Operational Buffer
Designing exactly to rated capacity leaves no room for any variance. The 10% operational buffer is not optional — it is the difference between a line that hits throughput targets on difficult days and one that falls short every time conditions are slightly off.
Mistake 5 — Mismatched Steam Supply
A cutting line that outruns its steam supply produces downtime, not throughput. Steam drum capacity must be calculated as part of the cutting line design, not separately.
