Aluminum Aging: The Final Step in Aluminum Processing
In our previous blogs, we explored the science of solution heat treatment and the different equipment used for this process: drop bottom furnaces and horizontal quench systems. Now, as we close out this blog series it's time to focus on the final stage of the aluminum heat treatment journey: Aging. This critical step transforms the soft, quenched aluminum into a high-performance material ready to meet the demands of modern engineering.
The Aluminum Aging Process: A Controlled Transformation
After quenching, the aluminum alloy is in a supersaturated state, with the alloying elements trapped within its structure. Aging, also known as precipitation hardening, involves reheating the quenched material to a lower temperature range (typically 225°F to 425°F) and holding it there for a specific duration of time, usually several hours.
This controlled heating allows the trapped alloying elements to gradually come out of solution and form finely dispersed precipitates within the aluminum matrix. These precipitates act as obstacles to the movement of dislocations (defects in the crystal structure), significantly strengthening the aluminum alloy.
The Benefits of Aluminum Aging
Aluminum aging is essential to achieve the mechanical properties required for high-stress applications. Without it, aluminum remains too soft for use in many processes. Aging enhances several key properties of aluminum alloys:
- Increased Tensile Strength: The ability to withstand stretching is significantly improved.
- Enhanced Yield Strength: Resistance to permanent deformation under stress is increased, improving structural integrity.
- Improved Hardness: Surfaces become more resistant to scratches, dents, and abrasions.
- Controlled Ductility: While ductility decreases during aging, it can be carefully controlled to achieve the desired balance between strength and flexibility.
Natural Aging vs. Artificial Aging
There are two primary approaches to the aluminum aging process: natural aging and artificial aging. While both achieve similar results, artificial aging offers superior speed, control, and consistency.
- Natural Aging: Occurs at room temperature over an extended period of time. While it’s an effective approach for certain alloys, it’s not practical for most commercial applications due to the lengthy aluminum processing time.
- Artificial Aging: Achieved through controlled heating in an industrial oven, it significantly accelerates the process and allows for precise control over the final properties.
Many general-use ovens have a low air recirculation rate, which can negatively impact heating uniformity. Parts at the outer edges of a load heat up faster than those in the center, leading to inconsistencies in aging. This can cause certain parts to be harder or softer than intended, potentially leading to quality issues, rework, or product failures. To overcome these challenges, aluminum aging ovens require specialized design features for optimal part results.
Key Features of High Performance Aluminum Age Ovens
When designing or selecting an aluminum age oven, it's important to consider several key features to ensure optimal performance and part results. Below are design considerations for your next aluminum age oven:
ROBUST CONVECTION AIRFLOW
Convection airflow refers to the air recirculating inside the heating chamber, and is the driving force behind efficient heat transfer in an age oven. Aluminum has a high thermal conductivity—over four times that of steel—which allows it to absorb heat rapidly. Purpose-built age ovens utilize high-speed air recirculation for even heating across the entire load.
The airflow rate is measured in cubic feet per minute (CFM) and is often expressed in "air changes per minute" (CPM). While general-use ovens may operate at just 5 CPM, high-performance age ovens operate at 30 to 50 CPM. This higher airflow rate ensures faster and more uniform heating of parts, which can significantly reduce cycle times and improve part quality.
MORE AIRFLOW = BETTER PERFORMANCE
Airflow volume is one of the most critical factors in optimizing oven performance. In a typical 8’ wide x 10’ long x 7’ high oven, the difference between 5 CPM and 50 CPM is significant. At 350°F, a 5 CPM oven circulates about 8,230 pounds of air per hour, while a 50 CPM oven circulates 82,300 pounds of air per hour across the load of aluminum.
The impact on cycle times is profound. For instance, heating a load to 350°F takes approximately 30 minutes at 5 CPM, but only 15 minutes at 50 CPM. Similarly, when the heat is turned off at the end of the cycle and the exhaust blower is turned on, the aluminum cooling times are reduced as well, allowing for quicker processing and throughput. This improved processing efficiency can translate into a 20% or greater productivity increase for each cycle, offering a substantial return on investment over the lifespan of the equipment.
ADVANCED TEMPERATURE CONTROL SYSTEMS
Precise temperature control is essential for achieving consistent results in the aluminum aging process. A unique feature that shortens the heat-up time in the aging process is "thermal overdrive" or "controlled heat head." This feature temporarily raises the air temperature above the desired part temperature at the start of the cycle, forcing the load to heat more quickly. Once the parts approach the desired temperature, the oven’s control system reduces the air temperature to avoid overheating.
Thermal overdrive allows for faster heating without compromising part quality. By embedding thermocouples within the load, the system monitors temperature in real time and makes adjustments accordingly. This level of control results in parts that are heated consistently, regardless of their location within the load.
In addition to thermal overdrive, multi-recipe controllers enable operators to set specific parameters for different types of parts. These parameters include the ramp rate, peak allowable load temperature, and maximum heating rate. Such customization allows for better process flexibility and improved overall performance across varying loads.
THE PRODUCTIVITY PAYOFF
When evaluating an aluminum age oven for your facility, it’s crucial to consider factors like airflow, cycle time, and temperature control. The investment in a specialized aluminum age oven can yield significant returns in productivity, part quality, and operational efficiency.
- Faster Cycle Times: By increasing airflow and leveraging thermal overdrive, cycle times are significantly reduced, allowing manufacturers to produce more parts in less time.
- Improved Product Quality: Consistent airflow and precise temperature control prevent uneven aging, ensuring that every part in a load meets the required hardness specifications.
- Energy Savings: Shorter cycle times and reduced energy consumption during heating and cooling contribute to lower operational costs.
- Enhanced Equipment Longevity: Purpose-built age ovens are designed for the demands of aluminum aging and better withstand wear and tear on components.
Wisconsin Oven Aluminum Age Ovens: Precision and Performance
Wisconsin Oven is a leading manufacturer of high-performance aluminum age ovens designed to deliver exceptional results and meet the stringent demands of industry. Key features of Wisconsin Oven’s age ovens include:
CUSTOMIZATION AND FLEXIBILITY
Wisconsin Oven offers a wide range of customization options to meet the specific needs of each customer. Aluminum age ovens are available in over many standard sizes, with custom configurations and conveyorized options to accommodate diverse production needs. Equipment can be designed as electric, gas-fired, or indirect gas-fired heated with airflow configurations to optimize temperature uniformity throughout the oven chamber, ensuring consistent and repeatable aging results.
SUPERIOR PERFORMANCE AND RELIABILITY
Wisconsin Oven's aluminum age ovens are built to deliver precise, consistent, and repeatable results. Advanced temperature control and robust airflow design ensure temperature uniformity as tight as ±5°F throughout the operating temperature range, resulting in consistent aging outcomes. The ovens can be designed with extremely rapid heating and cooling capabilities, enabling faster cycle times and increased productivity. Built with heavy-duty construction, Wisconsin Oven's age ovens provide long-lasting performance and reliability, backed by an industry-leading 3 year or 5 year warranty, depending on the model.
ADVANCED CONTROLS AND MONITORING
Wisconsin Oven aging ovens utilize state-of-the-art microprocessor-based controllers for precise temperature control and process optimization, ensuring consistent performance. Data acquisition systems are available to enable real-time monitoring of critical process parameters, such as temperature, airflow and chamber pressure, to maintain quality and pyrometric compliance. Ovens can be designed to meet or exceed stringent industry standards like AMS2750F, BAC5620, CQI9, and others.
QUALITY ASSURANCE AND CUSTOMER SUPPORT
To guarantee consistent performance and reliability, every Wisconsin Oven aluminum age oven undergoes extensive testing and inspection. Each oven is factory-tested for heat up time and temperature uniformity prior to shipment, reducing installation time and ensuring optimal performance upon arrival. The Wisconsin Oven service team supports customers with aftermarket options, including installation, training, and preventive maintenance programs.
A High Performance Aluminum Age Oven for Your Process
Aluminum aging is a critical step in the processing of aluminum alloys. Dedicated to high performance operation, equipment longevity, and design customization, Wisconsin Oven supplies high quality aluminum age ovens to manufacturers across the globe. Whether you're processing extrusions, sheet metal, castings, or other part configurations, our aluminum age ovens deliver the precision, performance, and reliability you need to achieve superior results. Contact us today to learn more!