How Are Two-Piece Aerosol Cans Made? A Guide to DWI and Transfer Press Production
Two-piece aerosol cans have become one of the most refined achievements in high-volume metal forming. Unlike their three-piece counterparts, which are assembled from a body, top, and bottom, two-piece cans are formed from a single piece of metal that becomes both the body and the base in one seamless structure. This design reduces material joints, improves structural integrity, and supports the tight tolerances that aerosol packaging demands. For manufacturers in this space, the production method chosen, whether DWI (draw and wall ironing) or transfer press production, shapes everything from throughput rates to tooling investment and final can geometry.
Understanding the mechanics behind each approach is essential for anyone involved in aerosol can manufacturing, from production engineers evaluating new lines to procurement specialists comparing supplier capabilities. This guide breaks down both processes, explains the quality factors that matter most, and helps clarify which method suits which application.
DWI vs. transfer press: two paths to one can
Both the DWI process and transfer press production arrive at the same destination, a formed two-piece aerosol can body, but they take fundamentally different routes to get there. The choice between them is not simply a matter of preference; it reflects the material being processed, the production volume required, and the geometric complexity of the final part.
DWI (draw and wall ironing) is a high-speed, high-volume process predominantly used with aluminum. It is particularly well-established among major aerosol packaging producers such as Ardagh, Ball, Moravia, and Nussbaum, who rely on it for continuous, large-scale output. Transfer press production, by contrast, is better suited to steel-based materials and applications where multi-stage deep drawing is required to achieve more complex geometries or tighter dimensional control. Both methods begin with a flat metal strip fed from a coil, but from that starting point, the tooling philosophy, press mechanics, and forming sequence diverge significantly.
Inside the DWI process: from coil to finished can body
The DWI process converts a flat metal blank into a finished can body through a sequence of drawing and ironing operations performed at very high speed. It is one of the most productive metal forming techniques available for thin-walled cylindrical containers.
Blanking and cupping
The process begins when a wide aluminum coil is fed into a cupping press. Here, circular blanks are punched from the strip and immediately drawn into shallow cups in a single stroke, combining the blanking and cupping operations efficiently. This first-stage cup establishes the base diameter and initial wall height that all subsequent operations will refine.
Drawing and ironing
The cup is then transferred into the body maker, where it passes through a series of ironing rings. Each ring progressively reduces the wall thickness while simultaneously increasing the can height. The ironing action stretches the metal against a precision mandrel, producing a thin, uniform wall with a thicker base, exactly the profile needed for a pressurized aerosol container. Final operations typically include trimming the open end to a consistent height, washing, and coating the interior surface before the dome or valve cup is attached.
The speed of DWI lines is one of their defining characteristics. Modern systems can produce hundreds of cans per minute, making them highly competitive for aluminum aerosol packaging at industrial scale. However, this throughput comes with significant tooling investment and limited flexibility when changing can diameters or heights.
How transfer press production forms two-piece aerosol cans
Transfer press production takes a more modular, multi-stage approach to forming two-piece can bodies, particularly where steel or more complex geometries are involved. Rather than relying on a single high-speed ironing sequence, a transfer press moves parts through a series of dedicated forming stations within one machine.
From cup to finished form
The process starts in the same way as DWI, with a metal strip fed from a coil into a cupping stage where blanks are drawn into initial cups. In a strip-fed transfer press (also called a multi-stage press or MSP), this cup is then gripped by a transfer system and moved through successive die stations. Each station performs a distinct forming operation, whether a drawing step, a calibration pass, or a finishing operation such as embossing or beading.
For aerosol can bodies, this staged approach allows the forming sequence to be precisely engineered around the material behavior and the required wall profile. The transfer system maintains consistent part positioning between stations, which is critical for achieving the dimensional accuracy that pressurized containers require. Explore the range of mechanical press solutions that support this kind of multi-stage production.
Material flexibility
One practical advantage of transfer press production is its compatibility with a broader range of materials. While DWI is strongly associated with aluminum, transfer presses handle steel, tinplate, and specialty coated materials with equal effectiveness. This makes them a strong fit for manufacturers whose product range spans different substrates or who need to switch between can specifications without rebuilding their entire production setup.
Key quality and tolerance factors in aerosol can forming
Regardless of which process is used, two-piece aerosol can bodies must meet demanding quality standards. Pressurized containers leave no margin for inconsistent wall thickness, out-of-round geometry, or surface defects that could compromise structural integrity or affect the sealing of the valve cup.
Wall thickness uniformity is perhaps the most critical variable. In DWI, the ironing sequence must be precisely calibrated to prevent thinning beyond acceptable limits, particularly at the transition between the wall and the base. In transfer press production, each drawing step must be controlled to avoid material cracking or wrinkling, both of which are signs that the reduction ratio between stages is not properly balanced.
Dimensional consistency across high production volumes is equally important. Can bodies that vary in height or diameter create problems downstream during filling, seaming, and valve attachment. Intelligent press controls and integrated diagnostics play a significant role here, enabling real-time monitoring of forming forces and automatic adjustment to compensate for material variation across a coil. The servo spindle press technology developed for precision forming applications reflects exactly this kind of process control capability.
Choosing the right production method for your application
The decision between DWI and transfer press production ultimately comes down to a combination of volume targets, material specifications, product geometry, and capital investment appetite. Neither method is universally superior; each is optimized for a different set of conditions.
DWI is the preferred route when producing aluminum aerosol cans at very high volumes with standardized dimensions. The process delivers outstanding output rates and proven reliability at scale, which is why it dominates the mainstream aluminum aerosol market. The trade-off is relatively high tooling cost and limited flexibility for diameter changes.
Transfer press production offers greater versatility and is better suited to applications where steel is the preferred material, where production volumes are mixed, or where the can geometry requires more controlled, multi-stage forming. It also integrates well into broader deep drawing operations, making it a practical choice for manufacturers who produce aerosol components alongside other formed parts such as battery cases or technical components. Manufacturers looking at deep drawing applications will find transfer press technology particularly relevant here.
For manufacturers evaluating a new line or upgrading existing capacity, the most productive starting point is a detailed review of part geometry, annual volume requirements, and material sourcing strategy. These three factors together will point clearly toward the process that delivers the best balance of productivity, quality, and lifecycle cost.
How H&T ProduktionsTechnologie supports aerosol can production
We at H&T ProduktionsTechnologie bring over 70 years of metal forming expertise directly to the challenges of two-piece aerosol can manufacturing. Our machine portfolio addresses both the cupping stage and the multi-stage forming process that define transfer press production, and our servo-driven systems deliver the precision and process stability that pressurized packaging demands.
Here is what we offer manufacturers in the aerosol packaging sector:
- Cupping presses engineered as vertical, double-action machines that combine blanking and cupping in a single stroke, converting wide metal strips into multiple high-quality cups with minimal material waste
- Strip-fed transfer presses (MSP) with integrated transfer systems for multi-stage deep drawing, calibration, embossing, and beading in a single machine
- ServoSpindlePress technology that provides unmatched control over forming force and slide position, resulting in optimized part geometry and reduced scrap rates
- Intelligent drive systems and integrated diagnostics for real-time process monitoring and consistent quality across high-volume production runs
- Tailored solutions and individual consulting to match machine configuration to specific can dimensions, materials, and output requirements
- Comprehensive after-sales service to support uptime and long service life throughout the machine lifecycle
Whether you are establishing a new aerosol can production line or optimizing an existing one, we are ready to discuss the right forming solution for your specific requirements. Contact our team today to start a conversation about how our press technology can support your production goals.
