1. First, they need to inform the bag manufacturer whether their filling equipment closed by manual or automatic.
- **Manual filling and sealing** only require folding the bag when closed the bag.
- **Automatic filling** (e.g., Haver & Boecker machines) typically uses ultrasonic heat-sealing, which places higher demands for the valve material. the valve should be heat-seated when there is carbon black powder on the valve. The valve material and construction are differ from the bag body.
2. Second, the thickness of the bag depends on its load capacity (e.g., 10kg, 12.5kg, 15kg, 20kg, or 25kg).
- Ideally, the customer should provide the density of the material being packed. Based on the weight, density, and supplier’s experience, the bag manufacturer can recommend a few bag options for testing.
3. Note: When confirming dimensions, there’s a difference between flat dimensions (unfilled bag) and filled dimensions (after loading).
4. Most importantly, the valve opening size must match the filling machine’s filling pipe.
- The customer should provide the **diameter of the machine’s filling pipe.
- The bag’s valve width (not diameter) should be slightly larger than the pipe’s diameter to ensure a proper fit.
- The valve width also determines the height of the filled rectangular bag.
5. Should the bag body perforation?
- This depends on whether the filling machine leaves residual air in the bag.
- Large filling machines may require **specific venting capacity**. The supplier will perforate the bag accordingly—holes must be **large enough to release air, but not so large that material leaks out. If the holes are too small, the bag may inflate like a balloon.
Once the bag dimensions, thickness, venting requirements, and sealing method (automatic/manual) are confirmed, the manufacturer can provide a **quote and produce samples.
