Automatic Filleting Machine Product

Overview

The automatic fish filleter is the centerpiece of modern premium seafood processing, combining precision cutting mechanics with real-time vision guidance to extract maximum usable flesh while minimizing bone contamination. The machine accepts deheaded fish bodies, orients each one via a servo-driven positioning conveyor, and uses a line-scan camera to map the spine and estimate optimal blade depth based on fish size and species. Two synchronized reciprocating blades—one for each body side—cut along the rib cage while following the spine contour at 0.5–2 mm depth, removing 92–96% of the loin while leaving minimal flesh on the bone. A secondary spine-cutting blade separates the dorsal and ventral loins from the backbone. Raw fillets then pass through a high-speed centrifugal drum or water-jet system that tumbles them against perforated walls, dislodging small pin bones and rib fragments through mechanical friction and washing. The final output is boneless or near-boneless fillets suitable for direct sale, further processing, or portioning.

Vision-guided filleting is 2–3 times faster than manual knife work and produces uniform thickness and bone recovery across all specimens, even when fish size or species varies within a batch. Machine learning algorithms trained on thousands of fish images can detect and adapt to body deformities, identifying the optimal cut line in real-time. This eliminates the need for operator re-tooling between batches and allows a single machine to handle multiple species (salmon, cod, tilapia, pollock) without mechanical changeover.

How it works

Deheaded fish bodies from upstream arrive on the positioning conveyor, belly-side up. A line-scan camera mounted above the conveyor captures a high-resolution lateral profile of each fish, transmitting image data to the vision PC at camera frame rate (up to 1000 fps). The industrial computer runs a convolutional neural network trained to detect the spinal column, estimate body thickness, and predict the optimal blade depth for fillet extraction without breaking the loin. Servo motors adjust the positioning conveyor's lateral and longitudinal offset, centering the spine directly under the primary blade carriage.

When the fish is correctly positioned, the PLC triggers the blade drive unit. Two reciprocating blades—mounted on opposite sides of the spinal centerline—stroke in unison at 30–80 strokes/minute, each cutting horizontally inward toward the bone at the programmed depth. The blade profile is contoured to follow rib cage geometry, removing flesh without excessive pressure. As the blade strokes, a pressure sensor in the hydraulic circuit monitors load; if bone contact is detected (sudden pressure spike), the PLC can reduce depth by 0.2 mm on the next stroke or signal an operator alert for manual inspection. After 5–20 strokes, the primary blades have separated most flesh from the rib cage on both sides. A secondary spine-cutting blade then executes a vertical slice perpendicular to the backbone, severing the fillets from the vertebral column.

The separated fillets (still attached to the backbone at the tail end) then slide down a polished stainless steel chute onto the bone separator conveyor. The centrifugal drum is running at 300–600 rpm, creating 8–15 g of radial force. Fillets tumble inside the perforated drum for 20–30 seconds; small pin bones and rib fragments are driven outward against the 3 mm holes and fall through. Simultaneously, chilled water at 10–15°C is circulated through the drum interior, carrying away bone dust and flushing the fillet surface. The centrifuge discharge deposits clean fillets onto a discharge conveyor, while bone-laden water returns to a settlement tank and hydrocyclone for solids removal and recirculation.

Key assemblies

Vision system: A 2 MP line-scan camera at 5 kHz line rate captures the dorsal contour of each fish as it passes beneath the sensor. The image stream is processed by the industrial vision PC running OpenCV for edge detection and TensorFlow for semantic segmentation of the spine centerline. The algorithm outputs a set of (x, y) coordinates representing the predicted spine path; the servo controller uses these to drive the positioning conveyor. Latency from image capture to conveyor adjustment is typically 50–100 ms, ensuring precise spine centering even at high throughput.

Blade carriage: Two primary blades (one per side) are mounted on precision linear ball-bearing rails separated by the width of the spinal column. Each blade is contoured to follow the ribs, with a cutting edge of 62 HRC hardened steel. The blade travel distance is typically 100–150 mm, driven by electro-hydraulic cylinders. A connecting rod or linkage converts hydraulic motion into synchronized blade strokes. Pressure feedback from load cells in the hydraulic circuit is relayed to the PLC for adaptive depth control.

Hydraulic precision system: A proportional pump (30 cc/rev) delivers oil at variable pressure and flow to pilot-operated directional valve, which modulates flow to the blade-drive cylinders. Unlike on-off solenoid systems, proportional control allows infinitely variable blade speed and pressure, eliminating shock and improving cut consistency. The system runs at 2000 psi nominal and includes pressure relief, check valves, and an internal tank filter.

Bone separator: The stainless steel centrifuge drum (300 mm diameter, 600 mm long) is driven by a 1–2 kW VFD motor at 300–600 rpm. Fillets are tumbled inside while chilled water sprays from a nozzle ring. Bone fragments are thrown outward and drop through 3 mm perforations into a lower chamber, where they flow to a collection bin. Water recirculates through a 150-micron mesh filter to remove sludge before returning to the spray system.

Controls: The vision PC runs proprietary or open-source (TensorFlow/OpenCV) algorithms for real-time spine detection. The PLC interfaces with the vision PC via Ethernet, receiving predicted blade depth and positioning commands. Servo drivers amplify PLC signals to the positioning motor and hydraulic proportional solenoid. An HMI touchscreen displays live camera feed, blade depth, fillet count, and bone removal efficiency metrics.

Performance and yield

Meat yield depends on fish species, size, and blade depth tuning. Atlantic salmon (3.5 kg avg) typically yields 60–65% fillet weight from whole fish (including the 20% head removal). Pin bone removal in the centrifuge improves consumer safety and product grade, allowing classification as "boneless" or "pin-bone-free" for premium market tiers. Residual bone fragments (< 2 mm) are typically 0.1–0.3% of fillet weight after centrifuge treatment.

Throughput varies with fish size: small herring (150 g) can be processed at 8–10 tonnes/hour, while large salmon (4 kg) drop to 2–3 tonnes/hour due to longer blade traverse and skin thickness. Multi-species facilities tune blade depth and conveyor speed between batches via the HMI, taking 10–15 minutes per changeover.

Maintenance and consumables

Blade life is 12–30 hours per set, depending on bone density and feed consistency. Stainless steel fillets and parts extend blade life by 15–20% versus fresh-caught wild fish. Blades are re-honed with ceramic stones every 4 hours and replaced when cutting edges reach 60 HRC hardness. Servo positioning motors require annual inspection for play and thermal growth; the ball-bearing rails should be flushed with light oil monthly.

Centrifuge drum perforations can clog with bone dust, reducing water flow and air release. Weekly cleaning with a soft brush and periodic replacement of the return-side 150-micron filter prevent this. Motor bearings on the separator should be checked for noise and play every 6 months.

Vision camera cleaning is critical: any film or scale deposit on the lens reduces image contrast and causes blade depth errors. Clean the window daily with a dry microfiber cloth; monthly, use a 70% isopropyl wipe. The camera should be replaced every 3–5 years due to sensor degradation.

Variants and integration

Smaller facilities (100–300 kg/hour) use manual-feed single-blade machines with fixed depth and no vision feedback, reducing cost to 40–50% of fully automatic systems. Mid-range (1–2 tonne/hour) machines have a single vision camera and proportional hydraulics but no bone separator. High-volume plants integrate filleting directly between the deheader and a downstream skinning machine, with intermediate conveyor and washdown stages. Some premium producers add a second automatic grader downstream, sorting fillets by size and quality (color, bloodline, defects) for separate market streams.