Written by Kagan Pittman and originally appearing on Engineering.com on June 25, 2018
Are you guilty of believing the aluminum extrusion myth?
Many design engineers looking for cost savings often overlook extruded aluminum manufacturing for stamped or machined parts, believing it to be an expensive and/or challenging process. This can be a costly mistake. Extruded aluminum allows manufacturers to produce complex profiles with as few parts as one and can save companies real money on production and overall product lifecycle costs.
Why? Light alloy extrusion is not always extensively covered in engineering schools and is sometimes ignored by design teams in favor of traditionally used techniques. As a result, many designers don’t have a strong background in relevant alloy properties, proper tolerancing or the latest related manufacturing and fabrication techniques.
According to Eric Becker, director of business development, manufactured components at Vitex Extrusion, “Engineers who limit themselves and their capabilities pay the cost in their designs, and so it pays to think outside the box.”
Fortunately, design engineers can work with extruded aluminum manufacturers to reduce parts, improve functionality and eliminate machining and tooling to save costs throughout the project.
Saving Costs with Aluminum Extrusion
To start, understanding the component’s end use and product requirements are essential to selecting the proper aluminum alloy. Aluminum offers properties like a high strength to weight ratio, corrosion resistance and electrical conductivity among other benefits, putting it in a different class than materials like stamped mild steel.
Take electrical products, for example. If a design engineer were to pot an extrusion and encapsulate it properly, it gives a rigidity to the component while making it look and feel higher value. For example, a 22-gauge stamped steel enclosure might require stiffening ribs to become rigid enough so that it doesn’t flex when handled or be larger than mechanically needed to allow for sufficient heat sink properties. However, with aluminum extrusion, rigidity and even elements like thermal conductivity and corrosion resistance are already built in due to its essential properties.
Designers can also create complex shapes with extruded aluminum to reduce part count and combine functions to further reduce manufacturing costs. Aluminum profiles produced in near net shape can incorporate holes, slots, or screw bosses into the shape, eliminating much of secondary operations. Designs can also work to eliminate welded assemblies and riveting, increasing overall strength and decreasing overall costs. Although the individual cost of the extrusion could be higher than a simple formed sheet steel part, the overall system parts are often significantly lower.
Furthermore, extrusion dies are significantly cheaper than injection molds or die casting molds. Stamped steel can also be changed for aluminum extrusions for weight reduction which translates to cost savings in shipping. However, before skipping too far ahead, it’s important to review design.
Extruded Aluminum Profile Designs and Design Reviews
Today’s designers are at an advantage with access to CAD, CAM and PLM software in which they can create and test their parts in a virtual space. In the digital world, designers can test tolerances, requirements and tweak designs as needed as issues, solutions and new ideas arise.
Once a design is agreed upon within the production team, it’s time to share their plans with their aluminum extrusion manufacturer.
An aluminum profile design review allows the manufacturer to work collaboratively with product development engineers to optimize designs. This is an essential step before beginning the manufacturing process. Possible issues resulting from poor communication are minimized and the manufacturer has a more complete understanding of what the design team needs.
“If you send a CAD file and it’s not correct or issues don’t get caught by your manufacturer who is already into the production process, you’re going to add a lot more cost and time to the job,” says Becker.
Design engineers can ensure errors like this don’t occur by being as open as possible with their aluminum extrusion manufacturer.
“I think designers are often reluctant to tap their manufacturer for advice and early input,” adds Becker. “One of the best things you can do is to get your manufacturer involved early. Let the manufacturers who have been producing thousands of parts like yours look at your design and let them know how it’s going to be used, because they’re going to see something you don’t.”
Once a design has been approved, the manufacturing process can begin.
From Billet to Final Product in the Aluminum Extrusion Manufacturing Process
The aluminum extrusion process allows custom dies to be made in significantly less time compared to other metal production processes, like die casting or blanking and stamping.
With an approved final design, a billet and extrusion tools are preheated before the billet is transferred and pushed with force against the die. The fully formed profile is then extruded and cooled.
Vitex Extrusion uses a Presezzi HECS high velocity, multi-sided air and water quench system that applies 600 gallons per minute of water at about 130 lbs. per square inch, depending on which alloy is being cooled. Rapid cooling preserves the extrusion profile’s characteristics, mechanical properties and tolerances, while preventing distortion.
The profile is then straightened along a “stretcher” to correct any possible distortions before being conveyor-fed to a saw to be cut to pre-specified lengths. Maximum strength, hardness and ductility are attained after the aging process.
“With new advances in alloys and the cooling technology, there’s no need to go to a higher cost alloy than standard grades of aluminum for many applications,” Becker explains. “We can tweak the way we cool or age the alloy and it can be just as strong. There’s a lot of flexibility and cost savings in that.”
If necessary, extrusions can be further fabricated. Vitex Extrusion’s fabrication capabilities include precision cutting, single and double head miter cutting, tapping, deburring, milling, drilling, punching and precision and long part CNC machining. Long part CNC machining uses long beds to machine parts of up to 19 feet in length in a single operation to substantially reduce machining time.
Once the unfinished aluminum is exposed to air, it naturally passivates, developing a transparent oxide coating, which is usually sufficient for surface protection. If additional surface protection is required, paint, powder coating or anodizing are suitable options.
Aluminum Extrusion Manufacturing with Vitex Extrusion
As manufacturing technologies advance, so too has aluminum extrusion techniques, making a viable solution across a number of industries.
“There is not a product type or industry where extrusion can’t be incorporated,” says Becker. “We’re seeing industries that never really gave aluminum extrusion a chance are now looking at it.”
Vitex Extrusion serves industries including building and consumer products, electronics, LED lighting, transportation and solar power applications. The manufacturer offers customers design for manufacturing support, extrusion manufacturing, fabrication, CNC machining, and extrusion finishing, and fulfillment services from their 115,000-square-foot facility in Franklin, New Hampshire.
Becker and the Vitex Extrusion team believe the knowledge gap about aluminum extrusion is the leading factor in unnecessary mistakes and costs from the design phase to end use. To combat this, the team produced a webinar on the 6 Mistakes Designers Make and How to Avoid Them.