Egg Grading and Packing Line

Overview

An egg grading and packing line takes loose shell eggs straight from the layer house and turns them into labeled retail packs. The work happens in a fixed order: load the eggs, wash and sanitize the shells, candle each egg under bright light to spot defects, tap each egg to find micro-cracks, weigh it, sort it by weight grade, then place it gently into a carton or tray. A single Egg Grading and Packing Line runs from 50,000 to 180,000 eggs per hour across 4 to 12 lanes, so every section must move at the same pitch without bruising or cracking shells.

The line is built around accuracy and gentleness. Eggs are fragile and food contact rules are strict, so the structure is stainless steel, the contact parts are food-grade, and the whole machine is designed for daily washdown. The Control and Vision System cabinet ties the sections together so an egg flagged at candling or crack detection is tracked all the way to a reject gate rather than reaching a carton.

Infeed and washing

Eggs arrive on farm trays. The Infeed and Accumulation Section lifts a stack of trays with the Tray Lift, and the Tray Unloader Head uses vacuum cups to lift a full row of eggs off each tray at once. The eggs land on the Accumulation Table, which buffers flow so a momentary gap upstream does not starve the rest of the line. The Lane Divider Rail rails then split the eggs into parallel lanes feeding the Infeed Roller Conveyor.

Washing comes next. The Washing and Sanitizing Section runs eggs under banks of soft nylon Wash Brush rollers while warm water at 40 to 45 degC flows from the Wash Spray Bar fed by the Wash Water Pump. Wash water is kept above the egg temperature so the shell membrane stays sealed and dirty water is not drawn inside. The Sanitizer Dosing Pump meters chlorine or peracetic sanitizer into the rinse, and the Wash Water Heater holds the temperature with a Heating Element. After washing, an Air Knife strips off surface water and the Dryer Blower finishes drying so the shells reach candling clean and dry.

Candling and crack detection

The Candling Station station inspects every egg optically. Inside a light-tight Candling Hood, a bright Candling Backlight back-illuminates each egg while a Candling Camera with a fixed Candling Lens captures the image. The Candling Spin Roller spins each egg so the camera sees the whole shell. The vision software reads blood spots, meat spots, dirt stains and shell cracks, and a Leak Detection Sensor catches eggs already leaking from a failed shell.

Some hairline cracks do not show under light, so the Crack Detection Station station adds an acoustic check. A row of Tapping Head fingers taps each shell lightly and an Acoustic Sensor microphone reads the sound. A sound shell rings cleanly while a cracked one returns a dull, damped signature. The Acoustic Processing Board, built on a Bare PCB with an Microcontroller and SMD Passive (R/C/L), classifies each tap and marks suspect eggs for rejection.

Weighing, grading and packing

Each egg then rides a tilting Weigh Carrier over an Grading Load Cell in the Weighing and Grading Section. The Weigh Acquisition Board reads the mass to within about 0.5 g and assigns a weight grade. As the carrier reaches the lane for its grade, the Grade Drop Gate drops and the egg rolls off into that lane. The Carrier Chain keeps the carriers moving at a fixed pitch driven by a Servo Motor through a Helical Gear Pair.

Before packing, the Transfer and Orientation Section section spins eggs to a known position on its Orientation Roller set and gathers them to the carton pitch with the Indexing Finger Bar. The Packing Station then lifts a full row with the Vacuum Pack Head and its soft Suction Cup gripping fed by the Vacuum Pump. A Pressure Sensor confirms grip before each lift, and the Packing Gantry running on Ball Screw and Linear Guide Rail axes lowers the eggs into the carton. The Carton and Tray Handling section feeds empty packs through the Carton Denester, closes filled cartons at the Lid Closer, and prints grade, date and lot at the Print and Apply Labeler. Any flagged pack is pushed off by the Reject Diverter.

Construction, variants and use

Everything sits on the Frame and Hygiene Enclosure, a welded stainless Base Frame with Sheet Metal Panel guards, Washdown Drip Tray trays under the wet sections, and interlocked Interlocked Guard Door access. Bearings such as Ball Bearing are sealed for washdown and seals use an O-Ring Set rated for hot water and sanitizer.

Smaller lines drop the acoustic crack station and pack into fixed carton sizes; large packing centers add several packing heads, robot palletizing and full traceability per carton. The same platform serves table-egg packers, hatcheries sorting hatching eggs, and processors feeding a breaking plant. Capacity is set by lane count and weigher pitch, while pack flexibility comes from the Packing Gantry and denester tooling. Throughput, grade accuracy and gentle handling are what separate one build from another, and the Control and Vision System system is where those are tuned for a given operation.