Open Mouth Bag Filler

An open mouth bag filler (also called an open mouth bagger) is a machine that fills pre-made open-top bags by gripping the open bag mouth, spreading it open under a fill spout, dosing a target weight of product (powder, granule or pellet), vibrating to settle the product and level the bag top, then releasing the bag to a closing station. The bag-closing step (sewing, heat sealing or glueing) is performed by a separate closer unit inline. Open mouth baggers are used for 1–50kg bags of flour, pet food, animal feed, coffee, sugar, chemical powder, fertilizer and industrial minerals.

Open mouth bagger: bags are pre-made with all sides sealed except the top opening. Bag top is sealed after filling (sewing, heat seal, glue). Better for: products requiring visible fill level, label on top, easy reclosable opening; food products (flour, pet food, coffee, sugar) where product quality and presentation matter; any product where contamination of the fill spout from inside the bag is a concern. Valve bag filler: bags have a small valve opening; all sides are sealed before and after filling through the valve only. Better for: fine, dusty powders (cement, lime, gypsum) where dust control is critical; high-speed production (1,200 bags/hr+); bags where a clean, fully-sealed exterior is required. For food products, open mouth baggers are generally preferred. For cement and chemical powders, valve bag fillers are the industry norm.

Compatible bag sizes: 1kg (small retail bags) to 50kg (industrial jumbo bags). Most common: 10kg, 25kg, 50kg. Compatible bag materials: Woven polypropylene (PP) bags — standard for grain, fertilizer, construction materials; highly durable. Kraft paper (single or multi-wall) bags — food-grade option for flour, coffee, pet food, agricultural seed. PE (polyethylene) bags — heat-sealable, moisture-resistant, used for chemicals, de-icing salt. Non-woven PP or PE — premium retail pet food and specialty food bags. Laminated bags (PE/foil/paper) — high-barrier option for moisture or oxygen-sensitive products.

Accuracy depends on the dosing method. Net-weight dosing (bag hung on load cells): ±0.1–0.2% for free-flowing and moderate products; ±0.3% for very cohesive or sticky products. Volumetric dosing (auger or cup): ±0.5–1.5% depending on product density consistency. Gross-weight dosing (platform scale): ±0.2–0.5%. For regulatory or trade-certified weighing (NTEP, OIML), choose a load cell net-weight model. For general industrial use where ±0.5% is acceptable, volumetric or gross-weight models offer faster output and lower cost.

Yes. Tool-free bag size changeover is standard on modern open mouth baggers. Adjustment points: fill spout width (to match bag opening width), bag gripper spacing (to match bag width), fill level/vibration time (for different bag heights), closing unit width (for sewing or heat sealer). Typical changeover time: 10–30 minutes for an experienced operator. For high-SKU operations, automatic servo-driven format adjustment reduces changeover to 5 minutes. Bag sizes within the same machine range can be switched without tools using marked scale positions.

A semi-automatic open mouth bagger (manual bag placement, net-weight, 1–25kg): from $12,000–$30,000 USD. Fully automatic with bag magazine, auto placement, net-weight and sewing closer: $40,000–$90,000 USD. High-speed rotary open mouth bagging system (6–12 stations): $100,000–$250,000 USD. Turnkey line with palletiser and conveyor: add $30,000–$80,000 USD. Contact us with your bag size range, product type and bags/hr target for a project-specific quotation.