Aluminum Extrusion Design Guide for AngleLock Structures

The special qualities of aluminum help engineers and product makers brush aside design limitations and invite innovation. The lightweight, modular, and corrosion-resistant nature of extruded aluminum systems have improved both new and existing applications in many industries.

But there’s still more to unlock. New levels of performance. New applications altogether.

Many of these possibilities don’t exist with traditional aluminum framing systems such as tube-and-joint, strut channels, and even T-slot extrusions. The way you can design with an advanced, self-aligning extrusion system like AngleLock is very different from the way you do with T-slots. 

The goal of this aluminum extrusion design guide is threefold. We’ll reinforce key points universal to aluminum extrusions, educate you on AngleLock-specific design practices, and get you excited about unlocking new product possibilities! 

7 Aluminum Extrusion Design Guidelines for Structure-Ready Framing

When designing with aluminum extrusions for a job with major efficiency or durability demands, look for these opportunities for improvement:

1. Treat it like steel – stiff
2. Configuring joints
3. Three-way brackets
4. Threaded inserts
5. Strength: Choose optimizing, not overengineering
6. Specs
7. Smooth and sleek for form and function

1. Treat It Like Steel – Stiff

While the systems have many benefits, the meaning of “advanced” and “self-aligning” aluminum framing can be boiled down in one sentence:

For the first time, you can design extruded aluminum structures similarly to welded steel.

This is what makes the AngleLock system different from other aluminum extrusion framing. The rigidity of a T-slot structure suffers because it relies on friction-based joints, which loosen and weaken over time. AngleLock uses self-aligning, fixed connections – meaning, angled fasteners and high-strength brackets – that physically cannot slip out of alignment thanks to their unique engineering. 

From the start, this expanded range of performance also expands the range of applications for aluminum. Because aluminum is far lighter, its strength-weight ratio is more than 2x that of mild steel. Forget hybrid assemblies of modular, cheap T-slots and rigid steel – you can design them with AngleLock as a sleeker, singular assembly with fewer brackets. Or, you can take that rusting frame you thought required steel’s rigidity, and convert it to corrosion-resistant aluminum.

Self-aligning connections afford you more flexibility in product and machine design – spend some time on creativity! You won’t need to think so hard about all the reaction forces involved, or how components might slip and slide under stress.

2. Configure Joints Wisely

Picking the right extrusion profiles is only part of a structure’s success. The way you treat connections has a huge impact on the assembly’s rigidity and strength.

Let’s start with what you shouldn’t do … and what you no longer need to do. 

Load capacity is always a question mark when its supporting cast is a series of friction-based joints. To get around this inherent weakness, traditional T-slot design encourages reaction force-based joints. An example is positioning extrusions on top of each other, rather than bolted in from the sides. This way, force moves directly from the horizontal profiles to the vertical profiles, creating a mechanical stop.

Many self-aligning brackets allow you to design differently than what you’d normally settle for with T-slots. Except for in extreme circumstances, AngleLock brackets are so strong that you can still use side-mounted designs in some applications where you normally couldn’t. AngleLock butt joint mounting plates, and even hinges, can outperform traditional products in face-mounting situations.

The added flexibility comes from the joint’s ability to hold more weight than with other methods. The mechanically locking joints allow each profile to retain its full strength potential.

What else should you know about brackets and fasteners as you create a concept?

• Be mindful of bracket orientation if a panel is nearby. Because the screws are angled, you won’t be able to tighten them fully if they’re facing the wrong direction.
  
  
• Don’t assume you need the strongest, biggest assembly plate. Make room for only the number of fasteners you need. (More on this in a minute.) If using self-aligning connections, you should be able to reduce the plate’s size and weight.
  
  
• Each fastener comes with an “ultimate strength” designation – the point at which it’ll fail. No matter the system, it’s still technically possible for an extreme force to pull bolts, screws, and nuts out of the profile.

3. 3-Way Corner Brackets

The 3-way corner bracket is a staple of skillful design work with aluminum structural framing. Yet many customers don’t fully grasp the use of it until they see it for themselves.

Three-way corners don’t exist in the same way in the T-slot world. There, such a joint requires two brackets (at minimum) for three profiles, plus two brackets to mount the top plate. Sometimes you can transform a friction-only joint into a stronger three-way by threading a fastener directly into the end of the profile. Some traditional T-slot companies have versions of three-way brackets, but only for low-strength applications.

That still leaves you with three brackets to pay for, extra weight, and an unsightly visual – which is why we recommend true 3-way brackets.

Three-way corner brackets in the AngleLock system take care of three profiles – and the top plate – all at once. If you’re looking to save component costs and weight, this is an easy place to start. The connection will still be stronger and more precise than a T-slot equivalent. The element of precision is particularly valuable if you’re designing machine guarding or a sensor assembly, where sagging and misalignment can impact safety or QA.

4. Internal Connectors

Does your product concept include a panel that fits in a slot? If so, you’ll need a non-intrusive connector.

In these situations, a threaded insert brings many advantages to aluminum connection design:

• Strong & durable connection options for modular systems
• Usable at various points on the profile to meet specific design requirements
• Distributes loads more evenly across connection points
• Negates the need for complex and expensive machining

Beyond these universal benefits, an AngleLock threaded insert stands out even further. How? By offering much more strength while not standing out at all (visually). 

Our threaded insert’s self-tapping body provides a secure hold; all you need to do is hand drill it into the frame. The material is 7075-T6 aluminum, so there’s no need to worry about strength. These low-profile inserts are virtually invisible from the side, so consider them another tool in your kit for balancing form and function.

Encourage yourself to discover new uses for these fastening components!

Related Resource: How to Use 3-Way Corners & Threaded Inserts

5. Strength: Choose Optimizing, Not Overengineering

T-slot users tend to either underengineer their builds (because they don’t account for dynamic forces) or overengineer them (because they’re terrified of dynamic forces). Even welded steel users overengineer for strength by 3-4x to give the perception of safety.

Self-aligning systems make it easy to find the perfect actor for the perfect role.

Because their joints mechanically lock, all profiles with self-aligning connections start at 100% strength. With the outcomes of your connections predictable, apply standard- and heavy-duty profiles where they make the most sense for the assembly. Add strength where you need it, and cut costs by using standard-duty components in less critical areas.

This isn’t to suggest you can be reckless with your use of aluminum building systems. In the end, safety should play the leading role in your decisions. Include these checks and balances in your safety evals:

• The accuracy of calculations
• The environment inside and outside the finished product
• The consequences of structural failure
• The cost of overbuilding for safety

6. Remember Your Specs

Engineers often face dimensional decisions for projects where 1-2 specific performance traits are paramount. 

If you need accuracy above all else, start with rigidity and engineer around that. If lightweight design is the ticket to success, start with your material’s strength-weight ratio.

A quick example: a lightweight electric presser. While managing heaviness would be important, the #1 priority is allowing absolutely zero deflection into the system. A well-designed presser will be so rigid you could drive a tank over it. In other applications (like aviation), weight challenges might put rigidity on the back burner.

Over-Engineering

Over-engineering, the practice of designing a structure with more capacity than necessary, can lead to unnecessarily expensive solutions. To avoid this, carefully work through your key formulas.

#1 – Bending moment:

• Perpendicular force * distance from point

#2 – Extrusion-specific properties

Since this is a little more complex, here’s a free profile calculator. What you’ll need is the:

• Bending moment
• Unsupported length
• Moment of inertia
• Applied force/location

Each product page on the AngleLock website includes all necessary product specs, including bending moment details. Engineers can use these specs to make informed, predictive decisions.