Selecting the right aluminum alloy is a crucial step in planning the manufacturing process. Each grade has its own unique characteristics and responds to stress and environmental conditions according to its chemistry and mechanical properties. It’s important for designers and manufacturers to carefully consider the strengths and weaknesses of each grade before coming to a final decision regarding material.
Unfortunately, it’s not always possible to conduct an extended prototyping and testing phase prior to launching a product or application. That’s why smart producers will partner with a trusted materials supplier who has a wealth of experience with a variety of materials. Being able to consult with an expert can often be the difference between the success and failure of a project.
Today we’ll be looking at two popular cast aluminum plate products, alloys 2618 and 5083. We’ll compare the properties of each, discuss their benefits and drawbacks, and go over some common applications for each.
What is cast aluminum plate?
Before examining the differences between 2618 and 5083 cast aluminum plate, it would be instructive to take a moment and look at how cast aluminum plate is made. This process is important for ensuring that your aluminum alloys are properly produced and will have the desired properties.
The first step in the process involves the casting of aluminum into slab or round billet form. The molten aluminum is poured into casting pits, producing billets or slabs. Round cast and scalped billets can be provided in sizes up to 39” in diameter and slabs are available up to almost 39” thick and 94” wide.
The slabs are then homogenized in large furnaces. Homogenization disperses the alloying elements trapped in the metal’s grain boundaries during the casting process. The process involves heating the material to a temperature below its melting point and holding it for a determined period. This allows the segregated elements to diffuse back into the aluminum matrix to perform their functions for the material’s physical and mechanical properties.
The slabs are then sawcut into various thicknesses and may undergo additional machining processes according to their size. 5083 thicknesses 4” and under are often precision machined to tight tolerances for use as tooling plate.
What are the properties of 2618 aluminum?
2618 is a popular alloy in the 2000 series of aluminum grades, which are known for their hardness and high strength, as well as for being heat-treatable and weldable. Although it may be heat treated, it has excellent mechanical properties in its as-cast state. The primary alloying agent is copper. 2618 has a density of .101 lb/in³ and exhibits superior thermal conductivity to 5083.
2618 exhibits excellent machinability and is dimensionally stable in the cast condition. It readily accepts coating processes such as anodizing and nickel. It is easily polished and able to receive surface treatments such as mold texturing. The thorough homogenizing process insures consistent properties throughout the cross section of larger blocks, which is of great importance in the work area of larger mold applications.
Again, 2618 cast plate is heat treatable, but it will become less dimensionally stable after the process.
What are the properties of 5083 aluminum?
5083 aluminum alloy comes from the 5000 series, whose alloys are recognized for being highly weldable with good corrosion resistance in marine environments. Its main alloying agent is magnesium and it has a density of .096 lb/in3. It is not recommended for higher temperature applications.
This grade shares many of the advantages of 2618 cast plate regarding weldability, machinability, surface treatments, coatings and consistent properties. 5083’s lower density imparts a weight savings over 2618 and some other aluminum grades.
While this grade is homogenized, it can’t be heat treated to improve properties or performance.
What applications are 2618 and 5083 commonly used in?
Due to its high strength and hardness along with its improved performance at high temperatures, the most common applications you’ll find using 2618 cast plate involve the aerospace, high performance automotive and plastics processing industries. It is commonly found in pistons and engine blocks. Its resistance to the onset of thermal fatigue makes it well suited for high temperature aerospace composite tooling, The increased thermal conductivity of 2618 lends itself well to all manner of plastic mold applications, including rotational molds, blow molding, low volume injection molds, compression molds, reaction injection molds (RIM) and resin transfer molds.
While 5083 cast aluminum plate will be found in a wide range of plastic mold applications as well, its increased corrosion resistance makes it particularly effective for use in expanded polypropylene and expanded polystyrene molds. These often have applications for the automotive and packaging industries.
A very popular application for the 5083 chemistry is cast tooling plate. Thicknesses up to 4” are precision machined to tight tolerances for the manufacture of checking fixtures, robotic and automation components, foundry patterns, vacuum and router tables, packaging and printing machinery, inspection equipment and machining jigs. The dimensional stability and tight flatness tolerances inherent in 5083 cast tooling plate are critical to applications where accuracy is of primary importance.
Your Technical Services Professional
Choosing between two different alloys can be difficult. That’s why partnering with a trusted material supplier makes so much sense. At Clinton Aluminum, our team has seen it all, and we are committed to helping each one of our customers through every step of the procurement process. We’re standing ready to answer questions about demanding applications. With an average of nearly thirteen years working in the industry, our experience and familiarity will be immediately obvious.
As the Midwest’s leading supplier of aluminum and stainless steel products, Clinton Aluminum has a proven track record of success helping clients. Please contact us today to learn more about how Clinton Aluminum can help make your business more competitive!
