28mm Aluminum ROPP Cap

ROPP (Roll-On Pilfer Proof) caps refer to tamper-evident aluminum screw caps that are mechanically rolled onto the necks of glass bottles. After opening, a permanent tamper-evident ring mark remains, ensuring the integrity of the packaging.

The 28mm aluminum ROPP (Roll-On Pilfer Proof) cap is a tamper-evident sealing device commonly used to seal glass bottles and plastic PET beverage containers. These caps are designed to provide a tight seal, ensuring product integrity and consumer safety.

As a mature and continuously innovative packaging solution, the 28mm aluminum ROPP cap plays an important role in multiple industries including alcoholic beverages, soft drinks, food, and pharmaceuticals.

As one of the most popular cap specifications on the market today, the 28mm aluminum ROPP (Roll-On Pilfer-Proof) cap has become the preferred packaging component for many well-known brands due to its excellent sealing performance, tamper-evident features, and attractive appearance.

28mm aluminum ROPP bottle cap

Common Specifications and Dimensions of 28mm Aluminum ROPP Caps

Basic Dimensional Parameters of 28mm Aluminum ROPP Cap

The core dimensional parameters of the 28mm aluminum ROPP cap revolve around the nominal diameter of "28mm", but in actual applications, specific dimensions may vary slightly due to differing industry and product requirements.

Basic Dimensional Parameters of 28mm Aluminum ROPP Cap

Dimensional Parameter	Common Specification (mm)	Tolerance Range (mm)	Remarks
Nominal Diameter	28	±0.15	Corresponds to bottle mouth diameter
Cap Height	15-18	±0.2	Common sizes are 15.5mm and 18mm
Thread Outer Diameter	28.1-28.25	±0.15	Matches bottle mouth thread
Cap Blank Diameter	51-53.8	±0.5	Raw material size
Tamper-Evident Ring Diameter	27.7-27.9	±0.05	Ensures tamper-evident function
Liner Thickness	0.32-0.34	±0.02	Affects sealing performance

28x15.5 mm Aluminum ROPP Cap
28x18 mm Aluminum ROPP Cap

28mm Aluminum ROPP Cap Specifications

Product Name:	28mm aluminum ROPP cap
External Size:	28.7±0.15mm
Bottle Finish:	GPI 1650/MCA 2
Liner:	TPE liner(PVC-free liner)
Height:	17.7mm
Color	Black, Blue, Gold, Red, Silver, White, Yellow, Customizable
Color
Type of printing	Logo printing/color according to the clients' requirements
Type of printing
Packing Method:	3500pcs/carton Carton size: 50x32x30cm

28mm Aluminum ROPP Cap Structure

ROPP (Roll-On Pilfer Proof): A method that uses mechanical means to roll the aluminum shell onto the bottle neck, forming threads and compressing the tamper-evident band.
28mm: Refers to the inner diameter of the cap, matching the size of the bottle neck.
Material: Made of lightweight, malleable aluminum, with corrosion resistance and recyclability.

Color coated and roller coated 28mm Aluminum ROPP Cap

Item	Description
Dimensions	Typically 28mm in diameter and 15–17.5mm in height, compatible with 28mm bottle necks under standards such as MCA2 and GPI 1650.
Material	Made from high-quality aluminum with good mechanical strength, corrosion resistance, and excellent formability, suitable for roll-on forming.
Tamper-Evident Feature	The cap includes a removable tamper-evident band, which separates from the cap body upon first opening, providing a clear visible indication of tampering to prevent unauthorized access.
Sealing Mechanism	Utilizes the Roll-On Pilfer Proof process, where a specialized capping machine precisely forms the aluminum cap onto the bottle neck threads, creating a firm seal. Combined with liner materials (such as EPE, PE, composite liners) to ensure seal integrity and leak-proof performance.

28mm Aluminum ROPP Cap Liner Options

Liner selection depends on the specific requirements of the sealed product:

PVC-Free Liners: Commonly used in cold-fill applications, achieving safe sealing without the need for PVC materials.
EPE (Expanded Polyethylene) Liners: Excellent sealing performance, suitable for various liquid products.
LDPE, PP, T-type and L-type Liners: Each liner is designed to withstand specific temperatures and is compatible with different filling processes. For example, T-type liners are suitable for low-carbonated soft drinks, while PP liners can withstand up to 121°C, making them ideal for hot-fill applications.

28mm Aluminum ROPP Cap Performance and Compatibility

Process Tolerance:

Temperature: Can withstand pasteurization (85°C/20 minutes), hot filling (95°C), and retort processes.
Filling Methods: Cold-fill, hot-fill, carbonated beverages, non-carbonated beverages.

Container Compatibility:

Materials: Glass bottles, PET plastic bottles, aluminum bottles.
Bottle Neck Standards: GPI-1621, GPI-1650, GPI-1655 (U.S. standards); MCA2/MCA3 (European standards).

28mm Aluminum ROPP Cap Features

Feature	Description
Tamper-Evident	The 28mm Aluminum ROPP Cap features a unique ROPP design with a tamper-evident band, leaving a clear sign of tampering when opened, allowing consumers to easily identify if the product has been opened. This design effectively prevents unauthorized tampering or opening, enhancing consumer safety and trust.
Secure Seal	The 28mm Aluminum ROPP Cap creates an airtight and leak-proof seal, ensuring that the contents are protected from external factors. This seal is especially crucial for volatile liquids or sensitive products (such as spirits, chemicals, etc.), effectively preventing leakage, oxidation, or contamination, ensuring the product's quality and stability.
Liner Options	The 28mm Aluminum ROPP Cap typically comes with various types of liners, such as foam liners, PVC liners, or paper pulp liners, to enhance the sealing effect against moisture, oxygen, or contaminants. Different liner materials can be selected based on the specific needs of the product, ensuring optimal sealing performance, which extends the shelf life and maintains the freshness and stability of the product.
Material	The 28mm Aluminum ROPP Cap is made from high-quality aluminum, providing excellent corrosion resistance and strength. The aluminum material not only gives the cap durability but also has strong antioxidant properties, maintaining its structural stability over long periods of use. This durability makes it widely used in beverage and chemical packaging.
Customization	The 28mm Aluminum ROPP Cap offers a variety of color options and can be custom printed based on customer needs. This allows brands to incorporate their unique designs into the cap, effectively enhancing product brand recognition and market competitiveness. Custom printing not only meets functional needs but also helps the brand stand out in the market and attract more consumer attention.

28mm Aluminum ROPP Cap Production Process

Raw Material Preparation and Processing

The production of 28mm aluminum ROPP caps begins with the selection and processing of high-quality raw materials:

Aluminum Selection: Mainly uses 8011 aluminum alloy; some high-end products use 3105 H16
Coil Preparation: Aluminum is typically supplied in coil form with a thickness between 0.2-0.4mm
Liner Material Preparation: Liner materials mainly include EVA, PE, silicone, etc., and must comply with food safety standards

Stamping and Preliminary Processing

Once raw materials are prepared, the key stamping and forming stage begins:

Blanking and Stamping: Precision punching machines are used to stamp the coils into individual cap blanks
First Drawing: Cap blanks are drawn into preliminary cap shapes through a stretching die
Secondary Processing: Includes trimming, shaping, and necking to further refine the cap dimensions

Threading and Tamper-Evident Ring Forming

Threads and tamper-evident rings are core functional components of ROPP caps:

Threading: Threads are formed on the inner wall of the cap using rolling or cutting methods
Tamper-Evident Ring Forming: A ring structure is formed at the bottom of the cap; the design of the breakable bridges must be precisely controlled
Top Processing: The cap top is flattened, embossed, or decorated as required

Surface Treatment and Printing Decoration

Surface treatment and printing decoration are key steps to enhance the visual appeal of the 28mm aluminum ROPP cap:

Surface Pretreatment: Includes cleaning, degreasing, and chemical treatment of the cap surface
Printing Techniques: Includes screen printing, offset printing, gravure printing, and digital printing
Special Effect Treatments: Such as hot stamping, silver stamping, embossing, debossing, etc.
Drying and Curing: Ensures firm ink adhesion; drying methods include hot air drying and UV curing

Liner Installation and Final Inspection

The final stage of production involves liner installation and strict quality inspection:

Liner Installation: Liner materials are installed on the inner side of the cap, usually by molding or adhesive application
Finished Product Inspection: Includes appearance inspection, functionality tests, sealing tests, and microbiological tests
Packaging and Storage: Packed in plastic bags or cartons; storage environment must be dry and well-ventilated

28mm Aluminum ROPP Cap Applications

28mm Aluminum ROPP Cap Application Fields

The 28mm Aluminum ROPP Cap is suitable for beverages in aluminum, glass, and plastic PET containers using cold filling, hot filling, carbonating, and pasteurization processes.

Application	Image	Description
Energy Drinks		The 28mm Aluminum ROPP Cap is used for packaging energy drinks. Since energy drinks often contain active and gaseous ingredients, the cap provides a strong seal to maintain the freshness and carbonation of the drink, preventing leaks and ensuring the stability and taste of the beverage during transport and storage.
Carbonated Soft Drinks		The 28mm Aluminum ROPP Cap is widely used for bottling carbonated soft drinks. This cap effectively retains the carbonation in the beverage, preventing the loss of bubbles and maintaining the refreshing taste, ensuring the quality of the beverage is preserved during distribution.
Baijiu (Chinese Liquor)		The 28mm Aluminum ROPP Cap is used for the packaging of Baijiu, effectively preventing oxidation and external contamination, preserving the flavor and aroma of the liquor. Its strong sealing ensures that the alcoholic product remains unaffected by the environment during long-term storage, maintaining optimal quality.
High-Quality Oil		The 28mm Aluminum ROPP Cap is used for sealing bottles of high-quality edible oils, effectively preventing the entry of air and light, which protects the quality of the oil and extends its shelf life. The tamper-evident design also provides additional safety for consumers, ensuring the product has not been contaminated.
Pharmaceuticals		The 28mm Aluminum ROPP Cap ensures a sterile environment in pharmaceutical packaging and prevents tampering. This cap provides excellent sealing to avoid external contamination, ensuring the safety and efficacy of medications, particularly in packaging that requires strict hygiene standards.
Cosmetics/Over-the-Counter Products		The 28mm Aluminum ROPP Cap is widely used in the packaging of cosmetics and over-the-counter products, such as essential oils, disinfectants, and serums. It offers a strong seal to prevent oxidation and deterioration, maintaining the stability of the products. The tamper-evident design ensures the safety of consumers.
Industrial		The 28mm Aluminum ROPP Cap is suitable for packaging chemicals, solvents, or agricultural chemicals, providing an effective seal to prevent harmful substances from leaking, ensuring safety during transportation and storage. The tamper-evident design also prevents misuse or accidental leakage, ensuring the safety of the product.

28mm Aluminum ROPP Cap Industry Case Studies

Application in the Alcohol Industry

The 28mm aluminum ROPP cap is widely used in the alcohol industry, especially for high-end products that demand high sealing performance and an attractive appearance:

Wine Packaging: Provides reliable sealing to prevent oxidation and microbial contamination
Spirits Packaging: Used for whiskey, vodka, etc., offering excellent sealing and tamper-evident performance

Beverage Industry Application Cases

The 28mm aluminum ROPP cap is also extensively used in the beverage industry:

Premium Drinking Water: Provides reliable sealing and an elegant appearance, such as Baisuishan and Laoshan mineral water
Juice and Tea Beverages: Suitable for products requiring high-temperature sterilization, offering good heat resistance
Functional Beverages: Used for energy drinks and sports drinks, offering reliable sealing and easy-to-open functionality
Carbonated Beverages: Capable of withstanding a certain amount of internal pressure, preventing CO₂ leakage

Other Applications

In addition to the alcohol and beverage industries, 28mm aluminum ROPP caps are also widely used in other sectors:

Food Packaging: Used for condiments, sauces, honey, etc., providing excellent sealing and moisture resistance
Pharmaceutical Packaging: Used for medicines and health supplements, offering reliable sealing and tamper-evident performance
Cosmetic Packaging: Used for creams, lotions, etc., providing excellent sealing and contamination protection
Industrial Applications: Used for lubricants, cleaners, etc., offering reliable sealing and leak prevention

28mm Aluminum ROPP Cap Customization

Surface Treatment: Available in polished, matte, or textured finishes.
Printing: Branding options through embossing, debossing, or printing logos.
Tamper-Evident Band Types: Single or double score bands for breakage control.

HC Aluminum offers a range of customization options to meet branding and product needs:

Color Options: Available in various colors such as black, silver, gold, blue, etc.
Logo Printing: Custom logos can be printed on the cap surface to enhance brand visibility.
Special Coatings: Options include matte, glossy, or metallic finishes to match product appearance.

28mm Aluminum ROPP Cap Advantages

Tamper-Evident: The anti-theft design ensures that any tampering is immediately noticeable, thereby enhancing consumer trust.
Compatibility: Suitable for a variety of container materials, including glass, aluminum, and PET bottles.
Process Versatility: Compatible with various filling and processing methods, providing flexibility for production.
Customization: Multi-color caps and custom printing options for effective brand promotion and marketing.
Durability: Aluminum is rust-resistant and maintains integrity under different temperatures.
Sustainability: Fully recyclable, in line with eco-friendly packaging trends.
Consumer Trust: The tamper-evident feature enhances the sense of product security for consumers.

28mm Aluminum ROPP Cap Packaging and Ordering

Colors: Standard configurations (white, black, red, blue, green, etc.).
Bulk Supply: Supplied in large quantities, usually in packaging boxes containing thousands of caps, suitable for mass production.
Minimum Order Quantity (MOQ): MOQ may vary.
Delivery Time: Depending on customization and order volume, delivery time may range from a few weeks to over a month.

Considerations

Liner Selection: Choose based on product compatibility (e.g., alcohol-resistant liners for spirits).
Regulatory Compliance: Must meet food-grade (FDA/EU) or pharmaceutical standards.
Minimum Order Quantity: Typically sold in bulk (e.g., 10, 000 pieces or more), with custom orders requiring tooling fees.

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