Once you've decided an open mouth bagger is the right fit for your 10–50kg bag line, the next question is which configuration actually matches your volume, bag type, and downstream automation. This isn't a single-model decision — throughput, accuracy, and closing method all shift depending on what you're filling and how fast. Here's what to check before you send an RFQ.
Semi-Automatic vs Fully Automatic Is the First Decision
ENZAC supplies open mouth baggers in two base configurations, plus a hybrid dual-format variant for lines running more than one bag size:
- Semi-automatic — throughput of 200–600 bags/hr, with manual bag insertion by one operator per line. Weighing accuracy runs ±50g at 25kg fills and ±100g at 50kg fills, using a net weigher selected by feed type (gravity, screw, or belt depending on material).
- Fully automatic — throughput of 600–1,200 bags/hr, with an automatic bag magazine that picks and opens each bag onto the filling spout without operator involvement. A dual-stage net weigher (pre-feed plus fine-feed) tightens accuracy to ±30g at 25kg fills at full production speed, and adds a bag flattener and reject system as standard.
The gap between the two isn't just speed — it's where labour sits in the line. Semi-automatic keeps one operator per line loading bags; fully automatic needs 0–1 operators, for monitoring only. That distinction should drive the decision more than the throughput number alone, especially where labour availability or shift coverage is the actual constraint.
Weighing and Feeding Type Selection
Feeder type is matched to material behaviour, not picked by preference:
| Material Characteristic | Recommended Feeder | Reason |
|---|---|---|
| Free-flowing granule (Carr Index < 20) | Gravity chute or slide gate | No mechanical feed needed; material flows by gravity |
| Fine cohesive powder (CI 20–40) | Screw feeder with VFD | Ensures consistent volumetric delivery despite poor flow |
| Fragile granule (e.g. urea, fertilizer) | Slow-speed screw or belt | Minimises particle breakage during fill cycle |
| High-density material (> 800 kg/m³) | Gravity with adjustable gate | High momentum makes screw fine-feed difficult at speed |
| Mixed or alternating materials | Multi-speed screw with recipe | Different materials need different feed rates stored per recipe |
Getting this wrong shows up the same way it does on ENZAC's FIBC filling range — a gravity feeder on a cohesive powder bridges and jams, while a screw feeder is often the only mechanism that reliably moves a moderate-Carr-Index powder at all.
Bag Type and Closing Method
Open mouth baggers on ENZAC's range handle PE film, PP woven, laminated PP, and kraft paper bags, with closing method matched to bag material rather than picked independently:
- Heat seal — PE film and laminated PP
- Stitch closing — PP woven bags
- Pinch-fold glue — kraft paper bags
- Combination closing — e.g. stitch plus heat-seal tape, where a project's compliance or transport requirements call for it
Format changeover between bag types and sizes runs under 5 minutes on ENZAC's range, via recipe change at the HMI. On a hybrid dual-format machine — the configuration ENZAC supplied for a PETRONAS urea bagging rejuvenation project, running 20kg and 50kg PP woven bags on the same line — changeover includes automatic bag magazine adjustment, not just a weight setting change.
Reference Configuration: Dual-Format Urea Line
ENZAC's PETRONAS reference project is a useful worked example of how these variables come together in practice. The line runs a screw feeder with VFD control (selected because urea is hygroscopic and moderately cohesive, with flowability that shifts with ambient humidity), a dual-stage net weigher holding ±50g accuracy across both 20kg and 50kg formats, and stitch closing with automatic tension adjustment per bag thickness. Three lines were commissioned to PETRONAS PTS mechanical, control, and safety standards, with FAT/SAT throughput and accuracy KPIs verified at acceptance.
The point isn't that every project needs this exact configuration — it's that the configuration was built around one material's specific properties, not selected off a generic catalogue spec.
Controls and Integration
Both configurations run on PLC control with touchscreen HMI (Siemens or Allen-Bradley), with recipe storage — 20 products on semi-automatic, unlimited formats on the fully automatic and hybrid ranges. Dust extraction is integrated at the fill spout as standard, designed to DOSH atmospheric emission standards for fine powder applications. Downstream, the bagger connects directly to checkweighing, VisionGuard™ vision inspection, and robotic or conventional palletizing — the same way ENZAC's other end-of-line equipment integrates, rather than requiring the bagger to be specified and installed in isolation.
Sizing Is Never From a Catalogue Number Alone
Even with a clear configuration table, throughput and accuracy figures are ceiling numbers for the mechanism, not a guaranteed line rate for every material. Bulk density, particle size, Carr Index, and moisture content for your specific product determine actual achievable speed and accuracy within a given configuration's stated range. ENZAC confirms machine suitability against your material data sheet before finalising a spec.
Review the full Open Mouth Bagger equipment page for the complete configuration range, material compatibility table, and industry applications.
Ready to talk about your open mouth bagging?
ENZAC supplies and commissions its open mouth bagging range in Malaysia, sized to your specific material, bag type, and required throughput. Send us your material data sheet and required bags/hr and we'll specify the right configuration and quote within 2 working days.