In the modern packaging industry, a bottle cap is not just a closure-it represents safety, tamper-evidence, and brand identity. Among them, aluminum ROPP (Roll-on Pilfer Proof) caps are widely used in wine, spirits, beverages, pharmaceuticals, edible oils, and other fields thanks to their excellent sealing, tamper-proof performance, and visual appeal.
The key materials supporting their quality are 8011 and 3105 aluminum sheets.

8011 Aluminum Sheet Strip

As a representative material in the aluminum-manganese alloy family, 8011 aluminum sheet and strip is one of the most commonly used and standard materials for manufacturing ROPP closures. 8011 aluminum sheet and strip boasts excellent ductility and formability. During complex processing steps like stamping, drawing, and thread rolling, it precisely conforms to the mold shape, ensuring dimensional accuracy and consistent appearance for each closure, effectively reducing scrap during production and lowering production costs for companies.

8011 aluminum sheet and strip boasts a high surface finish. After subsequent processing such as printing and painting, patterns and colors are clearly visible, enhancing the visual aesthetic of ROPP closures and helping brands convey their image through closure design, strengthening product recognition in the market.

8011 aluminum sheet and strip also possesses excellent corrosion resistance. Even in complex storage environments such as humidity, acidity, and alkalinity, it effectively resists external corrosion, ensuring the quality and safety of the product inside the closure and extending its shelf life.

3105 Aluminum Closure Plate

Compared to 8011 aluminum sheet, 3105 aluminum closure plate offers greater durability and stability. 3105 aluminum sheet and strip is an aluminum-manganese alloy, and its greatest strength lies in its high strength and excellent fatigue resistance. During the use of ROPP caps, whether subjected to bumps and collisions during transportation or the twisting force of consumers opening them, bottle caps made from 3105 aluminum sheet and strip maintain structural integrity, are less susceptible to deformation and breakage, and ensure consistent sealing performance.

3105 aluminum sheet and strip has excellent chemical stability and does not react chemically with various foods, beverages, pharmaceuticals, and other contents. In particular, its corrosion resistance to acidic contents (such as juice, vinegar, and certain spirits) is generally superior to 8011. 3105 aluminum sheet and strip fully comply with national food safety standards, eliminating the risk of harmful substance migration at the source.

3105 aluminum sheet and strip also has good welding performance. During the production process of ROPP caps, if special structural splicing processing is required, it can achieve a firm connection, further expanding the design and application space of ROPP caps.

Product Information: 8011 / 3105 Aluminum Sheets for ROPP Caps

Manufacturing Process of Aluminum ROPP Caps with 8011/3105 Sheets

1.Raw Material Preparation
Select 8011 or 3105 aluminum sheets suitable for closures, ensuring surfaces are free from scratches, dents, or black spots. Thickness, width, and mechanical properties must meet ROPP cap production requirements.

2.Coating & Printing

• Coating: Inner coating uses food-grade lacquer to prevent reactions with contents. Outer coating provides protection and serves as a printing base.

• Printing: High-speed multicolor printing applies logos, patterns, and text. A transparent protective varnish is usually added afterward.

3.Stamping & Forming

• Blanking: Sheets are fed into high-speed presses to punch out cap blanks.

• Initial forming: Cap blanks are pressed into cup-like shapes, preparing for thread rolling.

4.Trimming & Final Shaping
Trim edges for smoothness and form caps to match bottle necks precisely.

5.Liner Insertion
Liners (PE, EPE, foil, etc.) are inserted using automatic machines to ensure airtight sealing and leak prevention.

6.Thread Forming & Tamper Band Cutting

• Thread rolling: Closure threads are formed when applied to bottles, ensuring a tight fit.

• Tamper band cutting: The skirt is pressed and cut to form a tamper-evident ring, which separates upon first opening.

7.Quality Inspection & Packaging

• Appearance check: Printing quality, coating integrity.

• Dimensional check: Ensures caps meet standard specifications.

• Sealing performance test: Random sampling to verify tightness and leak-proof function.