Bulk Bag Filler Product

Overview

A bulk bag filler is an automated industrial bagging system designed to package dry bulk materials (powders, granules, ore, chemicals, food ingredients) into large flexible intermediate bulk containers (FIBCs, also called bulk bags, jumbo bags, or big bags). A typical FIBC holds 500–2000 kg and is 90 × 90 × 120 cm in dimensions.

The system comprises a [[bulk-bag-filler-frame|tall structural frame]] (3–4 m high), a Fill Head Assembly (spout with inflatable seal) at the top that connects to an upstream material source (conveyor, hopper, mill), a [[bulk-bag-filler-weighing-frame|platform scale]] under the bag with [[bulk-bag-filler-load-cells|load cells]], and a [[bulk-bag-filler-densification|vibrating deck]] that settles material after filling. A [[bulk-bag-filler-control-unit|PLC-based controller]] monitors the weight in real-time and cuts off material flow when the target weight is reached, achieving ±1–2% accuracy.

How It Works

An empty FIBC bag is positioned under the Fill Head Assembly, with its four corners suspended from the frame's Bag Hanger Lugs using [[bulk-bag-filler-hanger-shackles|suspension shackles]]. The bag opening is positioned around the Spout Body spout, and a Inflatable Seal Cuff (pneumatic cuff) is inflated to 3–5 PSI to seal the gap between spout and bag opening, preventing material spillage.

An operator (or automated system) enters the target fill weight (e.g., 1000 kg) into the Control Module. Material flows from an upstream source (e.g., a conveyor or discharge hopper) through a Material Gate Solenoid into the Fill Head Assembly.

As material falls into the bag, the Load Cell Support Frame (which supports the bag on four [[bulk-bag-filler-load-cell-unit|load cells]]) measures the total weight continuously. The Control Processor reads the four load cell signals via a [[bulk-bag-filler-signal-summing|summing amplifier]], calculates total weight, and compares it to the target.

To achieve accurate dosing, the control algorithm uses a dribble-feed strategy:

1. Fast fill phase: The Material Gate Solenoid is fully open, allowing rapid material flow (50–80% of target weight).
2. Slow-feed phase: When the weight exceeds 80% of target, the valve is throttled to allow only a trickle of material.
3. Cut-off: When weight reaches the target (within ±0.5%), the valve closes completely.

This prevents overfilling; without dribble-feed, inertia would cause material to continue flowing after the target is reached, causing overflow.

Once the bag is full, the Densification Deck vibrator is activated for 5–10 seconds. The vibration compacts and settles the material, reducing void space and allowing 5–15% more material to be added without exceeding bag height. After densification, the operator seals the bag (typically with stitching or a tie clip) and it is removed from the filler.

Mechanical Design

The Main Support Frame is a welded structural steel assembly (Grade 50): four vertical Frame Posts (200 × 200 mm box section, 3–4 m tall) connected by Cross-Beams (I-beams). The top of the frame has four Bag Hanger Lugs to which the bag corners are suspended.

The Fill Head Assembly assembly includes:

• Spout Body: A truncated cone (inlet 200 mm diameter, outlet 150 mm) that directs material from the source into the bag.
• Inflatable Seal Cuff: A neoprene or EPDM rubber cuff (200 mm diameter) that inflates to seal around the bag opening.
• Pneumatic Vibrator: A pneumatic impact vibrator that helps material flow through the spout, especially helpful for cohesive or angle-of-repose materials (powders, flour, cement).
• Chute Extension: An optional tapered extension that can be lowered to accommodate taller bags.

The Load Cell Support Frame is a sub-assembly mounted on Isolation Pads (natural rubber, ~20 Shore A) that isolate vibration from the main frame. The four [[bulk-bag-filler-load-cell-unit|load cells]] are mounted on this frame, and a Weighing Table (welded steel platform, 1200 × 1200 mm) sits on top. The bag rests on this platform and is suspended by the four shackles.

The Densification Deck deck is a separate Densification Plate (steel plate with rubber surface) positioned under the Fill Head Assembly. A Vibrator Motor (pneumatic or electric) causes the deck to vibrate at 3–10 Hz. The vibration settles and compacts material in the bag, reducing void space by 5–15%.

Electrical & Pneumatic Control

The Control Module is a wall-mounted panel containing:

• PLC: An ARM Cortex-M4 processor running real-time dosing firmware.
• Display: A 7" LCD touchscreen showing current weight, target weight, and countdown progress.
• Keypad: Numeric input for target weight and recipe selection.
• Solenoid Driver: A 24 V relay that opens/closes the Material Gate Solenoid (proportional valve) controlling material inlet flow.

The pneumatic system comprises:

• Compressor: A 1–2 kW rotary screw unit delivering 200–300 L/min at 5–8 bar.
• Receiver Tank: A 50–100 liter buffer tank smoothing pressure ripple.
• Regulator & Filter: A pressure regulator (0–10 bar) with a 5 µm coalescing filter ensuring clean, dry air to the inflatable seal and vibrators.
• Tubing: Food-grade polyurethane hose (6–8 mm OD) with quick-disconnects every 5 m for flexibility.

Air is distributed to:

• Inflatable Seal: 3–5 PSI continuously during fill (controlled by a solenoid valve).
• Spout Vibrator: 5–6 bar pulse (3–5 Hz) to assist material flow.
• Densification Vibrator: 5–6 bar continuous for 5–10 seconds after fill completion.

Accuracy & Densification

Achievable accuracy is ±1–2% of full scale, limited by:

• Load cell non-linearity: Class C3 cells are ±0.1%, contributing <0.1% error.
• Material density variation: Different batches of the same material can vary ±3–5% in density, causing variations in weight-to-volume ratio.
• Densification inconsistency: Vibration effectiveness depends on material properties (friction angle, cohesion); varying vibration intensity can change final density by ±5%.
• Dynamics: The dribble-feed algorithm must account for material "hang-up" in the spout after valve closure; tuning is material-specific.

One key advantage of densification is the ability to pack more material into the bag without exceeding its height. A typical 90 × 90 × 120 cm FIBC without densification can hold ~900 kg of loose powder; with 10–15% densification, it can hold ~1000–1050 kg, improving material throughput by 10% per bag.

Maintenance

Typical maintenance intervals:

• Daily: Check air compressor pressure and drain moisture from receiver tank (bottom valve).
• Weekly: Inspect inflatable seal for leaks or wear; test spout vibrator.
• Monthly: Clean load cell signal connectors; verify zero weight display with empty bag.
• Quarterly: Replace air filter element in compressor; calibrate scale with test weights.
• Annually: Inspect all welds for cracks; replace worn elastomer isolation pads; check solenoid valve seal.

Load cells and inflatable seals are the high-wear components; expected lifespan is 5–7 years for load cells and 2–3 years for rubber seal.

Applications

• Polymer Resin: Filling 1000 kg bags of polypropylene or polyethylene granules for injection molding.
• Cement & Aggregates: Bagging Portland cement, sand, gravel for construction.
• Chemicals: Packaging pigments, dyes, catalysts in FIBCs.
• Food Ingredients: Flour, sugar, salt, spices (food-grade FIBCs required).
• Pharmaceuticals: Active ingredients and excipients in bulk quantities.
• Minerals & Ore: Mining and milling operations bagging crushed ore or concentrates.
• Animal Feed: Bagging milled feed, grain blends, supplements.

Related Reading: Fill Head Assembly, Weighing Platform, Control Module, Densification Deck.