28mm (R3) Aluminium Screw Cap

The 28mm (R3) aluminium screw cap is a widely used metal accessory in the field of sealed packaging.

The 28mm R3 aluminium screw cap is made from lightweight and durable aluminium, featuring a straight-sided screw cap design, suitable for R3 (Pilfer28/PP28) thread specifications. Its inner ring uses expanded polyethylene (EPE) foam, providing tight sealing to prevent leakage and cross-contamination. Multiple surface finishes are available, including brushed silver, polished silver, gold, and black, making it perfectly compatible with glass and PET bottles in the food, beverage, cosmetics, and pharmaceutical industries.

28mm (R3) Aluminium Screw Cap Specifications

Item	Description
Outer Diameter	28mm, complies with R3 thread specification (also known as Pilfer28 or PP28).
Height	Approximately 13mm (typical height for R3 caps), with a lower profile than deep caps. Common height range is 11–20mm (e.g., AC1055 specification is 28mm×17mm).
Thread Profile	R3 (PP28), suitable for various glass syrup bottles, flasks, and PET bottles.
R3 Identification	Indicates thread specification, typically referring to a 3mm pitch (thread spacing) or proprietary thread series code. Ensures compatibility with R3 threaded necks or connectors.
Surface Finish	Brushed Aluminium: Matte textured finish that conceals fingerprints and adds a modern feel.
	Polished Silver: High gloss surface for a premium appearance, commonly used in high-end cosmetic packaging.
	Gold and Black: Colored coating options with EPE liners, used for product line differentiation and enhancing shelf appeal.
Cap Profile	Straight-sided (with knurling): External knurling provides a good grip, facilitating manual tightening and opening; design is compatible with automatic capping machines.

28mm (R3) Aluminium Screw Cap Material

Material: Made from aluminium, featuring lightweight, corrosion-resistant, and oil-resistant properties. Some high-end products may use industrial-grade aluminium alloys (such as ADC12), which offer excellent mechanical performance and heat resistance.

High-quality aluminium: Lightweight, durable, and corrosion-resistant. Suitable for industrial, automotive, or outdoor applications.
Optional anodizing treatment: Enhances corrosion resistance and provides color customization (e.g., black, silver, or gold).

Material and Structure

Item	Description
Cap Material	100% aluminium, corrosion-resistant with a high-quality metallic appearance.
Liner	White EPE (expanded polyethylene) foam disc, located inside the cap, forms an effective seal by compressing against the bottle mouth.

28mm (R3) Aluminium Screw Cap Sealing Performance

EPE Liner Function

The EPE liner serves as a compressible gasket; when the cap is tightened, the bottle mouth compresses the foam, forming a leak-proof barrier that effectively blocks liquids and vapors.

Prevents cross-contamination between consecutive fillings and maintains product freshness during long-term storage.

28mm (R3) Aluminium Screw Cap Design Features

Internal Thread: Precisely machined to ensure tight, leak-proof sealing when used with external threads on containers or tubes.
Sealing Mechanism: May include silicone or rubber gaskets/O-ring grooves for airtight/waterproof sealing.
Knurled or Textured Grip: Textured surface for easy handling and tightening.

28mm (R3) Aluminium Screw Cap Applications

Industry Coverage: Widely used in alcoholic beverages, food and beverages (e.g., carbonated drinks, soda water), daily chemicals, pharmaceuticals, cosmetics, and other packaging closures.

Application Area	Typical Use Description
Food and Beverage	Food colorings, syrups, extracts, oils, vinegar — requiring safe and inert metal caps.
Cosmetics and Personal Care	Essential oils, serums, lotions — offering smooth metal caps resistant to oils and solvent corrosion.
Pharmaceutical and Laboratory	Requires cleanroom-compatible metal-glass sealed medicine bottles and lab vials.

Suitable Containers: Suitable for bottles, plastic bottles, metal tubes, and other container materials.
Glass: Amber, transparent "syrup" shapes, rectangular and flask shapes, bottle neck diameter of 28 mm.
PET and Other Plastics: Suitable for PET, polycarbonate, and other hard plastic containers with PP28 threads. Glass bottles.

28mm (R3) Aluminium Screw Cap Production Process

Manufactured through precision molds, combined with stamping, spinning, and other processes to ensure thread accuracy and sealing performance.

These caps are widely used in the beverage, pharmaceutical, cosmetic, and other industries, offering excellent sealing, anti-counterfeiting, and mechanical strength. The production process must ensure dimensional accuracy, thread consistency, and high-quality standards for coating and sealing performance.

The production of 28mm (R3) aluminum screw caps is a precision process that involves material handling, coating, stamping, spinning, thread rolling, sealing, and inspection, requiring high automation and mold precision control to ensure the final product meets industry standards in sealing, aesthetics, and usability.

Process Step	Specific Operations	Equipment/Tools Used	Description
Raw Material Preparation	Selection of 3105/8011/5182 aluminum coil	Aluminum unwinding machine, tension control system	Material thickness approximately 0.20–0.25mm, in H14 or H16 state
Surface Pre-treatment	De-oiling, cleaning, chromating/chromeless treatment	Chemical cleaning line	Enhances coating adhesion and prevents corrosion
Coating Treatment	Primer → Top coat → Drying and curing	Roller coating line, drying oven	Using epoxy or polyester coatings to form a protective layer
Printing (Optional)	Logo or pattern printing + varnish gloss layer	Offset printer, pad printing equipment, UV drying system	Enhances brand recognition and aesthetics
Punching	Punching aluminum sheet into circular discs	High-speed punch press + progressive die	Ensures uniform dimensions and smooth edges
Cup Forming	Stretching the disc into a cup-shaped lid blank	Stretching machine, stamping die	Forms the preliminary lid body
Necking and Spinning	Controls bottle neck diameter and shaping	Spinning machine	Forms a 28mm R3 standard neck, ensuring verticality and concentricity
Thread Rolling	Rolling threads on the inner wall and corrugating the outer wall	Thread rolling machine, corrugating machine	Meets standard thread pitch and sealing requirements
Inserting Seal (Optional)	Inserting EPE or composite sealing gasket	Gasket press machine	Enhances liquid sealing performance, commonly used in beverage and liquor caps
Inspection	Checking dimensions, threads, sealing, appearance, printing, etc.	Inspection instruments, sealing testing devices	Ensures product quality meets export and industry standards
Packaging and Shipping	Automatic boxing, sealing, dust-proof treatment	Automatic packaging machine, sealing machine	Facilitates transportation, prevents damage and contamination

28mm (R3) Aluminium Screw Cap Inspection and Quality Control

Sealing Performance: Must pass temperature resistance tests (such as boiling conditions), corrosion resistance verification, and pressure tests.
Standardized Production: Adheres to industry standards to ensure dimensional tolerances and mechanical strength.

28mm (R3) Aluminium Screw Cap Customization and Special Requirements

Anti-tamper: Although the standard R3 cap does not have anti-tamper functionality, customized anti-tamper bands or induction liners can be added upon request.
Alternative Liners: PTFE or PELD disc inserts can replace EPE to improve chemical resistance or comply with FDA requirements.

This 28mm R3 aluminum screw cap combines practicality and aesthetics, offering reliable sealing performance in food, cosmetics, and laboratory applications. It is compatible with standard PP28 necks and offers various finishing options, making it a versatile choice for product packaging.

The following bottle caps may interest you