Pilfer proof caps, commonly used on spirits, wine, edible oil, beverages, and pharmaceutical bottles, rely on consistent forming behavior and reliable anti-tamper performance. The closure material must withstand high-speed stamping and roll-on processes, maintain dimensional stability, accept coatings and printing, and provide a clean surface suitable for food and pharmaceutical packaging.

As a manufacturer of aluminum closure stock, we supply 3105 aluminum closure sheet engineered for pilfer proof caps and ROPP (roll-on pilfer proof) caps. Our production focuses on alloy chemistry control, temper consistency, tight gauge tolerances, and surface conditions that support coating, printing, embossing, and knurling.

Why 3105 Alloy Is Used for Pilfer Proof Cap Stock

AA3105 is an Al-Mn alloy (3xxx series) designed for good formability, corrosion resistance, and stable mechanical properties after cold rolling and annealing. In pilfer proof closures, these characteristics translate into predictable cap forming, reduced risk of cracking during knurling, and consistent thread roll-on behavior on the bottling line.

Compared with very soft closure materials, 3105 can be supplied in tempers that balance strength and ductility, helping the cap retain shape while still forming cleanly. For brands and closure converters, this means fewer defects in cap-making and fewer torque-related failures during application.

Product Features for Pilfer Proof Caps

1) Controlled Temper for Stable Forming

Pilfer proof caps typically require controlled work-hardening to support:

• Deep drawing or shell forming without edge cracking

• Clean knurling and embossing definition

• Stable thread formation and tamper band integrity

• Reduced springback for consistent dimensions

We manufacture 3105 closure sheet in tempers commonly used in cap stock production, with coil-to-coil consistency to support high-speed presses.

2) Surface Quality for Coating and Printing

Closure sheets often receive lacquer, basecoat, or exterior decorative coatings. Surface cleanliness and uniformity influence coating adhesion and print appearance. Our process includes surface control measures to support:

• Coating wettability and adhesion

• Reduced pinholes and surface defects

• Consistent gloss and color appearance after printing

• Compatibility with common closure coating systems

3) Corrosion Resistance for Packaging Environments

3105 provides good corrosion resistance for typical storage and distribution conditions. With appropriate coating systems, the closure can perform in environments involving moisture, mild acidity, and temperature variation encountered in beverage and food supply chains.

4) Tight Gauge and Flatness Control

Gauge variation affects cap weight, forming force, and sealing behavior. Flatness affects feeding, blanking, and forming stability. Our rolling setup and inspection routines are designed to control:

• Thickness tolerance across coil length

• Camber and edge conditions for stable slitting

• Flatness suitable for coating lines and stamping

Technical Specifications (Typical Supply Range)

The parameters below reflect typical supply ranges for 3105 aluminum closure stock used in pilfer proof caps. Final values can be aligned to your cap design, coating system, tooling, and line speed.

Manufacturing Capabilities

As a factory with dedicated rolling and finishing resources for closure stock, we control key variables from incoming slab/billet management through cold rolling, annealing, slitting, and final inspection.

Rolling and Annealing Control

• Cold rolling schedules designed for closure gauges

• Annealing cycles to reach stable mechanical properties by temper

• Process monitoring to reduce property drift between coils

Slitting and Edge Quality

• Precision slitting to customer widths

• Edge trimming to reduce burr risk during stamping

• Coil shape control to support stable feeding

Optional Coating and Surface Preparation

Where required, we can supply coated coil suitable for closure conversion. Coating selection is aligned to end-use requirements (food contact, alcohol resistance, sterilization conditions) and customer printing processes.

Quality Control and Standards

Closure stock quality is defined not only by chemistry and tensile properties, but also by surface, cleanliness, and coil geometry. Our quality control system focuses on reducing variability that leads to cap-making downtime.

Incoming and In-Process Control

• Alloy verification and melt traceability

• Thickness and profile measurement through rolling

• Mechanical testing per lot and temper requirements

• Surface inspection for dents, scratches, inclusions, and oil residues

Final Inspection and Documentation

• Coil dimensional verification (width, ID, OD, weight)

• Flatness and camber checks based on agreed criteria

• Test certificates and inspection reports available per shipment

Compliance

We can supply to commonly referenced aluminum sheet standards such as ASTM B209 or EN 485, with additional customer-specific requirements for closure production.

Customization Options for Closure Converters

Pilfer proof caps vary by bottle finish, thread design, tamper band geometry, and branding requirements. To support different closure types and production lines, we provide customization for:

• Temper selection for forming severity and torque requirements

• Gauge optimization for weight and rigidity targets

• Slit width and coil weight matched to press and coating line capacity

• Surface finish and cleanliness targets for printing and coating

• Coating systems (interior/exterior) and primer selection (where applicable)

• Packaging design for long-distance export and warehouse storage

To accelerate qualification, we can support trial coil supply and process feedback loops with your cap-making team.

Application Scenarios and Target Industries

Our 3105 aluminum closure sheet for pilfer proof caps is typically used in:

• Spirits and wine: ROPP caps, tamper-evident closures, decorative printed caps

• Edible oil and condiments: pilfer proof caps requiring stable sealing and corrosion resistance

• Non-carbonated beverages: aluminum roll-on closures for glass bottles

• Pharmaceuticals and nutraceuticals: closures requiring clean surface and controlled coating compatibility

• Personal care and household products: tamper-evident caps where appearance and durability matter

Advantages Versus Common Alternatives

Selection of closure stock often comes down to balancing formability, strength, surface quality, and cost stability. In many pilfer proof cap programs, 3105 offers the following practical advantages versus common alternatives:

More Consistent Forming Window

3105 provides a stable balance of ductility and strength in closure tempers, helping reduce:

• Cracking at knurling or embossing features

• Irregular thread formation during roll-on

• Variability in cap skirt and tamper band behavior

Better Control of Coil-to-Coil Performance

By focusing production on closure sheet requirements, we control thickness and mechanical properties to support consistent press settings and fewer stoppages.

Coating and Printing Readiness

For branded closures, print quality and coating adhesion are critical. Our surface and cleanliness controls help reduce coating defects and improve appearance consistency.

Corrosion Resistance and Storage Stability

In distribution chains where humidity and temperature changes occur, 3105 provides a robust base material. When paired with the correct lacquer system, it supports long shelf life for packaged goods.

Supply Stability, Technical Support, and Long-Term Cooperation

Pilfer proof cap production depends on predictable material supply and consistent quality. As a manufacturer, we support customers with:

• Stable production scheduling for long-term programs

• Lot traceability and documented quality records

• Material selection guidance based on cap design and forming method

• Technical coordination during line trials, including temper and gauge adjustments

• Export-ready packaging and logistics planning for repeat shipments

If you share your cap specification, forming process, target temper, and coating requirements, we can propose a 3105 closure sheet configuration aligned to your production line and qualification standards, and support long-term supply with controlled consistency.