An open-mouth stitched bag is often the simplest choice when operators or semi-automatic equipment fill the bag and a separate sewing station closes the top. The mouth width, bag length and fabric behavior still need to fit the filler, conveyor and sewing head. A sample should be checked for filling access, top clearance and seam formation.
Automatic cement lines commonly use a valve format. Valve performance begins with geometry: the internal width, sleeve depth, opening direction and material must fit the filling spout without excessive resistance. A valve that is too tight can restrict product flow; one that is too loose can create product loss or an untidy closure. Buyers should therefore provide the filler make and model, spout drawing, target bags per minute and a current bag whenever possible.
A sewn-valve bag suits many established lines, while a block-bottom valve bag can form a more rectangular pack. Compatibility must be checked before changing formats.
Fast filling displaces air from inside the bag. If that air cannot leave at a controlled rate, the bag may inflate, fill slowly or remain unstable as it reaches the conveyor. Micro-perforation can provide defined air-release paths through a coated or laminated structure. The number, diameter and position of the holes should be established through a line trial because cement fineness, fill pressure and target speed affect the result.
More perforation is not automatically better. An overly open pattern can increase dust escape, while insufficient venting can restrict filling. The trial should record fill time, dust around the valve and bag body, closure behavior and filled-bag shape. Perforations manage process air; they do not replace a suitable moisture-control structure.
Pallet stability depends on fill-weight consistency, bag dimensions, surface friction and layer pattern. Block-bottom formats can present broad, even faces that support a regular stack. Anti-slip treatment may help when smooth bags move against one another, but the level should be checked on the conveyor and palletizer because excessive friction can interfere with bag movement.
Plain PP woven fabric provides carrying strength. PE coating creates a more closed surface, while gravure-printed BOPP film combines a laminated surface with detailed graphics. An inserted liner may be considered only when its opening and air-release behavior are compatible with the selected filling format. These options reduce normal exposure but do not replace dry storage or weather-protected transport.
Flexographic printing is suitable for straightforward designs on woven or coated fabric. Gravure printing is used on BOPP film before the film is laminated to the woven substrate. Artwork can include the cement grade, net weight, batch fields, handling marks and other required product information.
Relevant order checks may include fabric weight, tensile performance, print color and registration, lamination bond, valve dimensions, perforation pattern and seam or heat-seal integrity. The final specification should follow the approved bag sample and the buyer's filling-line test.
| Item | Reference Options |
| Product | PP woven cement packaging bags |
| Capacity | 25–50 kg; common projects include 25 kg, 40 kg and 50 kg |
| Material | PP woven fabric; virgin or recycled formulation available on request; optional PE coating or BOPP film |
| Fabric weight | 70–90 gsm |
| Bag width | 35–55 cm |
| Bag length | 50–70 cm |
| Mesh | 7 × 7 to 14 × 14 |
| Filling format | Stitched open mouth, sewn valve or block-bottom heat-sealed valve |
| Valve size | Custom to the filling spout; drawing, measurements or sample required |
| Air release | Controlled micro-perforation, subject to filling-line validation |
| Surface | Plain, coated or BOPP laminated; anti-slip treatment optional |
| Printing | Flexographic on woven/coated fabric; gravure-printed BOPP film, up to 8 colors after artwork review |
| Reference packing | 400–500 bags per bundle, or 5,000–10,000 machine-palletized bags per pallet; confirmed by bag size and shipping plan |
| MOQ, plate cost and lead time | Confirmed after the format, artwork, dimensions and quantity are reviewed |
Share your current bag and filling-line details with XH Packaging. We can prepare an open-mouth or valve construction for a focused trial, then refine valve fit, venting, closure and pallet shape from actual production results before the final specification is approved.
A stitched open-mouth bag is often practical when filling and sewing are separate steps. Its mouth width, top clearance and dimensions must match the filler, conveyor and sewing head. Provide the equipment details and a bag sample for a line trial.
There is no universal valve size. Internal width, sleeve depth and opening direction must fit the spout and closing action. Send the filler model, spout drawing and current bag for comparison.
They release air displaced during fast filling. The number, diameter and position of the perforations should be tested against cement fineness, fill pressure and target speed. Check fill time, dust escape and filled-bag shape on the line.
They can form a flatter, more regular pack that supports consistent pallet layers. Stability still depends on fill weight, dimensions, surface friction and the stacking pattern. Build a short stack with filled samples to compare performance.
Yes, if the new format matches the spout, bag magazine, closing method and conveyor guides. Line speed can also affect compatibility. Test the block-bottom bag on the existing equipment before switching formats.
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