8–50 μm Adjustable-Thickness Film Coating Machine for Jumbo Bag Fabric Coating

How Thick Should the Coating Be?

A thicker coating is not automatically better for jumbo bag fabric. An excessively thin layer may not provide the required surface coverage, while an unnecessarily thick layer increases resin consumption and may change fabric flexibility, folding and sewing behavior.

This 8–50 μm Adjustable-Thickness Film Coating Machine applies PE or PP layers from 0.008 to 0.050 mm. The target setting can be selected according to the woven substrate, single- or double-sided coating arrangement and final packaging requirements.

Factors Used to Select Coating Thickness

The 8–50 μm value is the machine’s available range. It does not mean that every jumbo bag fabric should use the same coating thickness.

How Thickness Is Adjusted

Coating thickness is affected by several connected settings:

• PE or PP melt condition;
• Extruder feed and screw settings;
• Die opening and effective coating width;
• Production-line speed;
• Single- or double-sided coating;
• Substrate tension and web position;
• Lamination pressure and cooling conditions.

If the line speed increases while resin output remains unchanged, the amount of resin applied per unit area may change. Thickness should therefore be rechecked whenever the fabric width, resin or line speed changes.

The listed configuration does not include a documented online thickness gauge. The machine should not be promoted as having automatic closed-loop thickness control unless that option is added and confirmed.

Application

The machine applies PE or PP extrusion coating to jumbo bag, FIBC and bulk bag woven fabric. It can produce single- or double-sided coated material for bulk packaging of fertilizer, minerals, metallurgical materials, cement and other industrial products. Buyers can define a target within the 8–50 μm range according to the fabric and packaging application. Moisture resistance, airtightness, powder containment and flex performance must still be verified through coating continuity, liner selection, seam construction and finished-bag testing.

Technical Specifications

Creating a Coating Recipe

For each jumbo bag fabric, record:

1. Substrate material, width and weight;
2. PE or PP resin grade;
3. Single- or double-sided arrangement;
4. Target thickness on each side;
5. Extrusion and die temperatures;
6. Production-line speed;
7. Measured coating thickness;
8. Surface and edge condition;
9. Finished roll condition;
   10? Need no issue. Continue.
10. Results of downstream printing and sewing trials.

A separate recipe for each substrate prevents different jumbo bag fabrics from being produced with one unchanged parameter set.

Sample Inspection

After trial production, inspect the coating for visible thickness variation, uncovered areas, pinholes, wrinkles and irregular edges. The effective coating width and finished roll alignment should also be checked.

For fine powder, moisture-sensitive or specialized industrial packaging, the coated fabric should be converted into a finished bag and tested accordingly. Coating thickness alone does not establish complete bag performance.

FAQ

Is a 50 μm coating always better than an 8 μm coating?

No. The suitable thickness depends on the substrate, resin, packaged material and finished-bag requirements. A thicker coating also increases resin consumption.

Can the two sides use different coating thicknesses?

The twin-extruder structure provides separate adjustment conditions, but the selected combination should be verified through trial production.

Does the machine automatically measure coating thickness online?

No online automatic thickness-gauge system is documented in the current configuration.

Can the coating completely replace an inner liner?

Not in every application. Liner requirements depend on particle size, moisture, cleanliness and closure conditions.