Home ApplicationAluminum Alloy Strip/Sheet for Closure Caps
2025-03-06 07:05:06
Aluminum alloy strip/sheet is a crucial material for manufacturing closure caps for various containers like bottles, jars, and aerosol cans.
Corrosion Resistance: Aluminum naturally forms a protective oxide layer that resists corrosion from the contents of the container and the environment. This is especially important for food and beverage products.
Malleability and Ductility: Aluminum is easily formed and deep-drawn into complex shapes required for closure caps. It can be stamped, rolled, and embossed
without cracking or tearing.
Lightweight: Reduces the overall weight of the packaging, contributing to lower transportation costs.
Recyclability: Aluminum is highly recyclable, making it an environmentally friendly packaging option.
Printability: Aluminum surfaces can be easily printed on with various inks and coatings for branding and labeling.
Barrier Properties: Provides a good barrier against light, oxygen, and moisture, helping to preserve the contents of the container.
Hygienic: Aluminum is non-toxic and does not support the growth of bacteria, making it safe for food and beverage contact.
Stable mechanical properties and good earing,less than 2% steadily or no ears for parts. Good plasticity capable of drawing deepth,at most 75mm,free of "orange peel"after stamping.
Better surface quality and uniform fine lines.
High thickness precision,up to ±0.005mm.
Aluminum alloy strip/sheet caps and coating/printing lines
|
Alloy |
Temper |
Performance Data |
Earing Rate |
Remark |
||
|
Yield Strength(MPa) |
Tensile Strength(Mpa) |
Elongation(%) |
||||
|
8011 |
H14/H16 |
≥2 |
125-155 |
≥2 |
≤2% |
Low strength,used forwine bottle cap and medicine lid |
|
3105 |
H14/H16 |
≥1 |
160-200 |
≥1 |
≤2% |
Medium strength,used for pressure vessel cover |
The specific alloy chosen depends on the application and required properties. Here are some of the most common:
8011 Aluminum Alloy: This is the most common alloy used for closure caps. It offers excellent formability, good corrosion resistance, and is relatively cost-effective. It's particularly well-suited for deep drawing and embossing. It is often preferred for ROPP (Roll On Pilfer Proof) caps.
3003 Aluminum Alloy: Offers better strength than 8011, but slightly lower formability. It's a good general-purpose alloy with good corrosion resistance. Often used in applications requiring a slightly stronger material.
5052 Aluminum Alloy: Known for its excellent corrosion resistance, especially in marine environments. It has good weldability and higher strength than 3003 or 8011. Less commonly used for standard closure caps due to its higher cost, but chosen when exceptional corrosion resistance is needed.
Other Alloys: Less common alloys like 1050 and 1060 may be used for specific applications where ultra-high purity is required, though they are less strong.
Temper: The temper designates the hardness and strength of the aluminum. Common tempers for closure caps include:
O (Annealed): Softest, most formable state.
H14, H16, H18 (Strain Hardened): Varying degrees of hardness and strength, achieved through cold working. H18 is the hardest. The choice depends on the forming process and the required rigidity of the cap.
Thickness: The thickness of the aluminum sheet/strip is crucial for the structural integrity of the cap. Typical thicknesses range from 0.2mm to 0.3mm, but can vary depending on the cap design and application.
Surface Finish: The surface finish affects the printability and appearance of the cap. Common finishes include:
Mill Finish: The as-rolled surface, usually requiring further treatment.
Pre-treated (e.g., Chromated or Conversion Coated): Improves paint adhesion and corrosion resistance.
Lacquered or Coated: Provides a decorative finish and additional protection.
Tolerance: Tight tolerances on thickness and width are important for consistent forming and sealing performance.
Coating/Lacquering: Aluminum closure caps are often coated with lacquers or other protective layers for several reasons:
Improved Corrosion Resistance: Provides an extra barrier against corrosion.
Enhanced Appearance: Allows for various colors and finishes.
Food Safety: Certain coatings are required for direct contact with food and beverages, ensuring no leaching of harmful substances.
Enhanced Printability: Provides a suitable surface for printing.
Lubrication: Lubricants are used during the forming process to reduce friction and prevent galling (material transfer). The lubricant must be compatible with the aluminum alloy and the intended application.
ROPP (Roll On Pilfer Proof) Caps: These caps are designed with a tamper-evident ring that breaks upon opening. 8011 alloy is commonly used for ROPP caps because of its excellent ductility, allowing the ring to be easily formed and broken.
Standards: Aluminum alloys and their use in food packaging are often subject to regulations and standards, such as those set by the FDA (Food and Drug Administration) in the US and similar organizations in other countries.
The typical manufacturing process for aluminum closure caps involves:
Slitting: Wide coils of aluminum are slit into narrower strips of the desired width.
Coating/Lacquering: The aluminum strip may be coated or lacquered.
Forming/Stamping/Deep Drawing: The aluminum strip is formed into the desired cap shape using stamping, deep drawing, or other forming processes.
Embossing (Optional): Logos, designs, or other features are embossed onto the cap.
Printing (Optional): The cap is printed with branding and labeling information.
Curling/Beading: The edges of the cap are curled or beaded for a smooth, safe finish.
Threading (for screw caps): Screw threads are formed on the cap.
Quality Control: The caps are inspected for defects and dimensional accuracy.
Packaging: The finished caps are packaged for shipment.
Application: What type of container will the cap be used on? What are the contents of the container? What are the environmental conditions?
Formability: How easily does the aluminum alloy form into the desired shape?
Strength: How strong does the cap need to be?
Corrosion Resistance: How resistant does the aluminum alloy need to be to corrosion?
Cost: What is the cost of the aluminum alloy?
Supplier Reliability: Does the supplier have a good reputation for quality and on-time delivery?
Certifications: Does the supplier have the necessary certifications (e.g., ISO 9001, food contact compliance)?
Traceability: Can the supplier trace the origin of the aluminum alloy?
When choosing an aluminum alloy supplier for closure caps, it's essential to provide them with detailed specifications, including:
Alloy type and temper
Thickness and width
Surface finish requirements
Tolerances
Coating requirements (if any)
Quantity required
