Aluminum containers, like those used for aerosol cans or some food packaging, are primarily manufactured using a process called impact extrusion.
Understanding the Impact Extrusion Process
For containers made of aluminum to be manufactured, an impact extrusion process is used. This method is highly effective for creating seamless, thin-walled containers with a closed end. It's a rapid cold-forming process where a metal slug is struck with high force inside a die cavity.
Here's a breakdown of the initial steps based on the process:
- Preparation of the Slug: Prior to the process starting, a metal slug is completely cooled and lubricated. This cooling and lubrication are crucial for preventing the aluminum from sticking to the tooling and ensuring smooth material flow during impact.
- Positioning: To begin the process, the slug has to be placed on a die. The die defines the shape and diameter of the base of the container.
- The Impact: A punch, typically smaller in diameter than the die cavity, strikes the slug with significant force. Because the slug is confined in the die cavity and the punch is smaller, the aluminum metal is forced to flow rapidly upwards around the punch, forming the walls of the container.
The force of the impact causes the aluminum to flow plastically, extruding upwards between the punch and the die. This single impact forms the basic can body in milliseconds.
Beyond the Basic Shape
After the initial impact extrusion creates the seamless body, the container undergoes further processing:
- Trimming: Excess material at the open end of the container is trimmed to the correct height.
- Necking and Shaping: The open end might be necked down (reduced in diameter) or shaped to accommodate a specific type of closure, such as a valve for aerosol cans or a screw thread.
- Cleaning and Washing: Containers are thoroughly cleaned to remove lubricants and any debris.
- Internal Coating: An internal coating is often applied to protect the product inside the container from interacting with the aluminum and vice versa.
- External Decoration: The outside of the container is typically decorated with paint, inks, and varnishes using high-speed printing techniques.
- Quality Control: Throughout the process, containers are inspected for defects in shape, wall thickness, dimensions, and coating integrity.
Key Advantages of Impact Extrusion for Aluminum:
- Seamless Body: Creates containers without side seams, enhancing structural integrity and pressure resistance (critical for aerosol cans).
- High Production Speed: The impact process is very fast, allowing for mass production.
- Material Efficiency: Can create thin-walled containers, saving material.
- Versatility: Allows for the creation of various shapes and sizes with integrated bases.
Examples of Aluminum Containers Made This Way
- Aerosol cans (for hairspray, deodorants, paints)
- Some beverage bottles
- Collapsible tubes (less common now than in the past for aluminum)
- Certain types of small canisters
In summary, the creation of aluminum containers relies heavily on the high-speed impact extrusion process, starting with a cooled and lubricated metal slug precisely placed on a die before being struck to form the container body.
