Why Use Aluminum?
- Aluminum versus Steel construction comparison table
- Tips for using Aluminum Extrusions to build structures
- Assembling with Aluminum
- Cost Concerns
- The Strength Issue
Assembling with Aluminum Extrusions
What do a rotary indexing assembly machine, a workstation, and the drum kit for the rock band Pink Floyd have in common? All three have been built with modular aluminum extrusions. And though few assemblers care how Nick Mason hangs his high hat, they are interested in building flexible equipment that can be reconfigured to meet changing demands. The life cycle of most products today is less than a year, especially in the electronics industry. Aluminum extrusions allow manufacturers to reconfigure their assembly lines quickly and easily.
More than just components for machine builders and systems integrators, aluminum extrusions are being used by assemblers to custom-build fixtures, workstations, material handling systems and machine guards.
There isn’t a plant in the country where I could not find applications for aluminum extrusions and components.
Assemblers are using bolt-together framing components to tailor workstations and machines to specific processes or floor space requirements. Because profiles can serve as conduits for compressed air or electricity, assemblers can install tool holders, parts bins and information boards to minimize wasted motion and workflow interruptions.
Modular framing components also enable assemblers to add automation incrementally, such as conveyors, gravity-fed parts racks and other material handling equipment. Many manufacturers subscribe to the continuous flow concept, but don’t carry it all the way through. It’s not uncommon to see a worker walking 20 steps to get a box.
Often an afterthought, machine guarding is a major application for modular aluminum components. Transparent panels can be bolted directly to a machine frame, or the machine can be surrounded by prefabricated screens hung from profiles mounted to secure base plates on the floor. Enclosures can be equipped with doors that swing open on hinges or slide open on linear bearings or casters.
Cost Concerns when building with Aluminum Extrusions
Compared with steel tubes, extruded aluminum extrusion profiles are more expensive. But, the higher material costs are more than offset by lower labor costs for assembling the project.
Steel frames have to be welded. Holes have to be drilled and tapped, and the frame has to be painted. An aluminum extrusion doesn’t have to be painted, and it’s modular. It’s got T-slots on all four sides. You never have to drill and tap holes.
Aluminum extrusions are also forgiving. Once you drill a hole in steel, it’s drilled.
Aluminum extrusion profiles can save money by giving engineers flexibility after the initial design of an automation project has been completed. With steel frames, you have to be pretty accurate up front before you start cutting the tubes, drilling the holes and welding the brackets. With aluminum, you don’t have to go into any kind of detail. If you need a control panel somewhere, you just have to worry about installing a couple of crossbeams to mount it. You can worry about the exact location of the beams later. The T-slots let you attach components at any time and at any location.
The Aluminum Extrusion Strength Issue
Though aluminum extrusion profiles have grown in popularity during the past several years, some engineers question the structural integrity of the aluminum material. When engineers think of aluminum, they think “light.” So, they tend to over design with these materials because they don’t “look” right. But, aluminum is strong enough to handle most manufacturing and assembly applications.
For high-strength applications, there are large aluminum extrusions, including 3 inch x 6 inch profiles that bolt together with M12 hardware.
Both steel and aluminum extruded structures will bend if they’re hit hard enough. But, because aluminum profiles are assembled with hand tools, you can take out the damaged member and put in a new one. With a steel structure, you’d have to cut out the damaged part, weld in a new one, and repaint.
Aluminum Extrusion Construction versus Steel Construction comparison table
The following table compares the cost of building a 24 by 24 by 18 inch machine frame with aluminum extrusions vs. steel tubes.
|Weight:||20 lbs||33 lbs|
|Steps:||Design time||Design time||Set up fixture|
|Bill of materials||Bill of materials||Weld|
|Purchase materials||Purchase materials||Grind welds, clean spatter|
|Assemble frame||Cut to length||Drill & tap holes|
|Deburr||Degrease, mask, prime & paint|
|Materials:||4 – 18 inch extrusions||30.24||4 – 18 inch extrusions||7.96|
|4 – 21 inch extrusions||35.28||4 – 21 inch extrusions||9.28|
|8 – saw cuts||14.8||Welding supplies, sandpaper, cleaning supplies, tape, paint||15|
|8 – inside corner brackets||32.4||5 – hours of labor @ $25/hour|
|32 – nuts & bolts||18.24|
|30 – minutes of labor @ $25/hour||12.5||125|
|Total Cost:||$143.46||$ 157.24|
Tips for building with T-Slotted Aluminum Extrusions
- Where possible, the horizontal aluminum extrusion profiles should extend across the entire length of the project. This simplifies connection of the bottom elements and improves the overall appearance.
- Aluminum Extrusion Structures should be designed to withstand the loads likely to be placed on them. Torsional stress at connection points should be avoided. For all connections, preference should be given to positive locking over friction resistance in the direction of applied force.
- Where possible, aluminum extrusion profiles should be installed at right angles to the anticipated load to achieve the maximum flexural strength.
- Avoid breaks in the supporting profile when installing additional attachments. This will mean greater stability, fewer cuts, fewer connections, and reduced assembly time.
- Extend the aluminum extrusion profiles with the aid of the corresponding fastening elements. Where possible, support them at the joint.
- If anodized surfaces are mounted in contact with each other, these surfaces should be lubricated to prevent noise generated by friction.
- If profile-based structures are likely to be exposed to extreme stresses, such as impact loads that might displace the points of attachment, a pin element should be installed to provide additional support.