Aluminum extrusions touch people’s lives everyday. Home and commercial appliances, HVAC equipment, power tools, electronics, office machines, medical equipment, fitness equipment, and vending machines, just to name a few, all incorporate aluminum extrusions to some extent.

From 12-in.-wide structural shapes to micro-tubing designed to transfer heat, aluminum extrusions rival steel, copper, plastic and other material solutions and come in a wide range of shapes and sizes for structural, aesthetic and thermal applications.

Aluminum extrusions of the right alloy and design can be as strong as structural steel. They can be manufactured with a tensile strength from 10 KSI to 100 KSI and be used in structural applications such as framing for exercise equipment, ladders and trailer frames.

They are also ideal for decorative applications such as furniture fascias and trim, picture frames, and housings for car amplifiers. Furniture quality finishes can include polyester and acrylic enamel, epoxy, polyester and T.G.I.C. powder, waterborne enamels in custom colors and textures, as well as two-tone painting, textured, and skid-resistant paints.

For thermal and electrical applications, aluminum extrusions are on par with copper, yet weigh half as much as equivalent copper components. Moreover, aluminum extrusions are fully recyclable, making them a suitable material for designing “green” products.

Hydro Aluminum, a global aluminum supplier, has been making aluminum extrusions in the U.S. for more than 50 years, functioning as a single-source supplier that partners with customers in extrusion design, finishing and complex contract manufacturing in markets ranging from transportation and construction, to consumer durables and electrical goods.

The company has helped design and manufacture an array of solutions for a variety of appliance applications.

Effective extrusions

Header for treadmill incorporates several features, including slot for easy mounting of control panel.

An attractive and easy-to-clean finish, durability, low weight, and high strength are some of the advantages aluminum extrusions provide. Aluminum extrusions have been used for frames, handles, trim pieces, and structural components for home appliances, commercial refrigeration, exercise equipment, and many other applications. Here are some examples.

For the top-rated treadmill manufacturer in the U.S., Hydro developed a series of extruded structural components that meet the requirements for lifetime performance, sturdiness, and furniture-quality finishes. One of the components — the header for a treadmill — was designed to incorporate multiple features, such as an easy-slide slot for mounting of the control panel, a rectangular knob for added strength, and holes to pass through electrical wires.

In electrical appliances, lighting systems, and industrial tools, heatsinks made of aluminum extrusions are common. When Hydro made the housing for an industrial lighting unit, it integrated an innovative heatsink feature — the flanges — right into the extrusion profile. Other features included built-in screw grooves and a modular design that allows easy snap-together assembly of the top and sides.

Aluminum extrusions are also used in all kinds of office equipment, including copiers and printers. Strength, low weight, formability, and tight-tolerance manufacturability are key characteristics for using aluminum extrusions in that market. These are made from drawn tubing, which comes from extruded stock, and must be free of defects. Hydro is the leading U.S. producer of organic photoconductors used in laser printers.

Heat exchangers

A brazed aluminum heat exchanger is a single, solid unit that offers lower weight, increased efficiency, and cost savings.

Refrigerators, freezers and HVAC/R units can also benefit from the use of aluminum extrusions and drawn tubing. Hydro supplies innovative precision tubing used in condensers, evaporators, radiators and heater cores. Using aluminum — as compared to steel or copper alternatives — costs less, is one-third the weight, and is better for the environment.

About 30 years ago, Hydro’s Precision Tubing sector was formed to develop new aluminum solutions for the automotive market. At that time, there was a tremendous push to find a more cost-effective and environmentally friendly alternative to copper heat exchangers and steel fluid lines. The unit provided an answer with precision micro-tubing, more commonly known as Multi-Port Extruded tubing (MPE), and drawn tubing. Today, these tubes represent the core of most heat exchangers in the automotive industry.

Subsequently, Hydro leveraged its experience in automotive heat-transfer technology for HVAC/R applications. The same driving factors applied. Consumer durables manufacturers needed something more cost effective to manufacture and kinder to the environment. The result was the application of its heat-exchanger MPE experience for condensers and evaporators to a wide variety of appliances.

Enlarge this picture Table 1. Aluminum MPE vs. Copper RTPF Condensing Unit.

MPE tubing has a large internal and external surface area, is an excellent heat conductor, and is very lightweight. Compared to copper solutions, it is much more energy-efficient and cost-effective. (See comparison chart in Table 1.)

In addition, Hydro offers Hybraz, a coating method utilizing a variety of special flux coatings for MPE components. The coated MPE come ready to braze with no additional filler or clad needed. During brazing, the flux coatings simply melt and join the components together. The Hybraz process also improves the components’ corrosion resistance. The product minimizes environmental hazards such as flux, speeds manufacturing processes, and reduces overall production costs because there is no need for additional fillers.

Design tips

Before and after examples of design changes that have no impact on the function of the extrusion, but which simplify production and lower costs. Far left pair demonstrates how a hollow extrusion can be designed for better dimensional control. The upper right pair shows how costs can be reduced by using fewer cavities. The lower right pair illustrates how increasing size can actually reduce weight and increase rigidity.

When design engineers are considering the potential for utilizing aluminum extrusions, there are some basic questions that need asking. First is whether aluminum is a suitable material for the components being investigated. Then, if so, how can aluminum profiles be integrated into the product design.

· Optimization: Designers should examine how extrusions can be optimally designed to take full advantage of the potential for built-in functional features such as slots, screw grooves, channels for bolts, clip joints, and hinges. When designing the part, engineers should also focus on putting the right amount of material only where it is needed and avoid making the extrusion heavier more expensive than necessary.

· Surface treatments: Not all extrusion surfaces are visible and need to be of the highest quality. Choose the right finish for the right application.

· Alloys: Specifying the most appropriate alloy to meet the required performance characteristics for the product. Alloys can improve product strength and formability, provide for better surface finishes, and enhance chemical and moisture resistance.

· Partnering: Look for a manufacturing partner that responds rapidly to questions and has a broad range of experience.

These brief and general tips just scratch the surface. More specific and detailed information can be found in an extensive 60-page Extrusion Design Manual from Hydro that can help walk design engineers through aluminum extrusion design considerations.

For more information email: lynn.brown@hydro.com