This document covers a simple method to decide what size and shape of 80/20 t-slot bar is required for a particular project – based on the weight the structure must support. There are infinite ways of engineering a t-slot aluminum structure, but the method outlined below is simple and straightforward – and should be easy to understand by non-engineers. Although we reference 80/20 brand t-slot extrusion data in this article, you could draw usable conclusions for other t-slot aluminum profiles if their size, weight and shapes were similar to 80/20 Inc. t-slot products.
The basic principle of choosing the right bar is understanding when a bar starts bending (commonly referred to as deflection) under a specific weight load.
There are 9 common methods for calculating deflection for t-slot aluminum bars as outlined below:
Today, we will be looking at the Two-End Supported method using Load Centered weight (circled in the chart above). While the two-end fixed test method is closest to the common vertical corner post method of design, it assumes an unbreakable connection with the vertical post. As fastener strength will play a role in any fixed design strength, we will use the two end supported method to better illustrate independent bar strength. In general, bars will bend easier when supported on each end versus being actually fastened between two vertical posts; consequently, the data and conclusions provided here will have a magnitude of safety if used in a two end fixed configuration.
How strong is each extrusion type or bar? We get that question all the time. As outlined above, it all depends on what you do to the bar. But in our opinion, the cleanest, simplest way to judge bar strength and deflection is to look at how far a bar will bend if we put all the weight in the middle of the bar while supporting both ends.
At F&L Industrial Solutions, we use a target defection of 1/10” or under for most t-slot structures. If a bar has a chance of bending more than 1/10”, then we usually redesign with a stronger bar. So it is important to remember that target – a tenth of one inch or under.
Look at the chart below.
As you can see, the 80/20 t-slot called 1010 (which is a 1” x 1”) bar will bend 1/10” when 46 lbs. is applied to the center of a 36” long bar, while both ends are supported. If we were building a simple table, we might say that this table could hold a maximum of 184 lbs. (4 horizontal bars forming the table top) on the edges of the table (how much the center of a tabletop could hold would be dependent on the tabletop material and thickness – a good subject for another day). That same table designed with the 2020 series (2” x 2”) could hold up to 2,304 lbs on the edges.
Note: It is important to realize that some of the weaker fastening methods can only hold 200 – 400 lbs., so using a heavy-duty fastener is imperative to achieve the same strength as the bar. For example, there would be no reason to spend money on strong 2020 bars and match them with inexpensive and fairly weak corner brackets as the fasteners would break before the bar bent 1/10”. By using stronger connectors like end fasteners and anchor fasteners and external gussets, one can easily create connections that are as strong or stronger than the bar.
Click here to read about fastener strength in a past issue of Extrusion Builder News.
The graph above is a good starting point, but it is only one data point – for 36” long bars. A longer bar would bend at a much lower weight, and a shorter bar will bend a higher weight. Usually when we are designing a t-slot aluminum structure, we will add additional supports so that there is rarely long unsupported bars. For example, if a table top was 8’ feet long – we would normally put two additional cross braces under the table top, and at least 6 vertical legs – thereby eliminating any long bar from carrying too much of the load.
One last thing to think about when designing t-slot aluminum structures or frames with 80/20 or any other brand of aluminum extrusions is maximum load. While the cart or table or frame you are designing may only be used for holding a 50 lb. piece of equipment, what will happen if a large person stands on it and uses it as a way to change a high light bulb? When designing, you should design for the very worst case scenario that you want your frame to survive.
In summary, here are the 4 simple steps to determining the t-slot aluminum bar you need for your frame:
Still confused? F&L Industrial Solutions offers free design and quotation of high quality 80/20 t-slot aluminum extrusion framing – so don’t be afraid to contact us to help. Click here to contact us to discuss your next project.
Ready to buy – visit our online Extrusion Shop.
Or call 858-602-1500.
If you would like to download and use the 80/20 Inc. deflection calculator that we used for this article, just click here to download.
One of the advantages of ordering furniture from Formaspace is that you are dealing directly with the manufacturer. This not only means you can be sure of getting high-quality American-made products, but you can also specify the materials and options best suited for your needs, including your choice between heavy-duty, fully welded steel frames or 80/20 aluminum extruded frames.
In previous articles, we have presented guidelines on how to choose the best surface material for your workstation and tables.
Now it’s time to look at the different options for the metal frame.
Before we can put the Formaspace name on a piece of furniture, it has to be exceptionally strong and durable. Why? Formaspace builds our products with an eye toward industrial applications, where they need to be tough enough to withstand constant use and rough and tumble treatment. To reinforce our commitment, we guarantee all of our furniture products for a full 12 years, even if you use them continuously, 24/7 (e.g. three shifts working around the clock).
HAVE A HEAVY DUTY WORKSTATION PROJECT STARTING SOON?
Every industry is unique. Formaspace creates benches and industrial furniture for customers with some of the most demanding requirements imaginable. We’ve installed custom solutions in even the most extreme physical environments. Backed with our own in-house industrial design and engineering team, we are able to work with you to understand your specific needs and then execute a solution, no matter how unique.
DESIGN WORKSTATIONS IN 3D
HAVE A HEAVY DUTY WORKSTATION PROJECT STARTING SOON?
Every industry is unique. Formaspace creates benches and industrial furniture for customers with some of the most demanding requirements imaginable. We’ve installed custom solutions in even the most extreme physical environments. Backed with our own in-house industrial design and engineering team, we are able to work with you to understand your specific needs and then execute a solution, no matter how unique.
DESIGN WORKSTATIONS IN 3D
Formaspace tables and workstations have to be strong as well as tough.
The load capacity of our Standard Duty benches, tables and workstations is 1,000 pounds (evenly distributed), making them much, much stronger than typical office furniture. But is it overkill? Not really. If you are using lightweight furniture with an internal core built out of a paper-like honeycomb material that’s held up by legs screwed into this same lightweight material (typical of many desks and tables from IKEA), you could have a serious, even life-threatening accident if the furniture were to collapse. How could this happen? Here are two common scenarios: too many workers sitting on desks and tables during a meeting, or workers stacking heavy boxes of books and paper on insubstantial benches, tables, or workstations.
If you anticipate needing to support loads heavier than 1,000 pounds, talk to your Formaspace Design Consultant about our Heavy Duty furniture configurations. This furniture can carry up to 20,000 pounds (evenly distributed).
Now that we’ve established that Formaspace benches, workstations, and tables are strong and durable, let’s look at the different options you have when specifying the metal frames for your new Formaspace furniture.
Steel is by far and away the most popular material choice for Formaspace furniture frames (we only use American-made steel). Our Standard Duty frames are made from 1 1/2” square tubing, while Heavy Duty frames use a full 2” square steel tube. The joints at the corners are fully welded on the factory floor by skilled Formaspace craftsmen at our production facility in Austin, Texas. Once the steel furniture frames are welded together, they are typically powder-coated, either in a clear color to preserve the ‘industrial look’ or a color of your choice.
Because steel frames are fully welded at the factory, they won’t need to be assembled or maintained (e.g. adjusted and/or tightened) during their lifetime at your office or facility. This is one of steel’s key advantages over 80/20 aluminum extrusion frames, which we will discuss next.
If the term extruded aluminum seems unfamiliar to you, you may be surprised to know that it’s actually a very common material. You’ll find that extruded aluminum is commonly used in most bathtub shower enclosures or in tracks supporting sliding patio doors.
How’s it made? When aluminum is heated to high temperatures, it can be forced (i.e. pressed or extruded) at a high pressure through a mold pattern to form long, straight material stock which can incorporate complex, cross-sectional designs.
The type of aluminum extrusions used by Formaspace for building furniture frames have square cross-sections with a t-shaped slot (e.g. void) incorporated into each facing side. By design, these t-slots allow the fasteners that hold the frame sections together to pass through. During assembly, the fasteners are pushed down the slots to the correct position — where they are held snug inside the slot rail. This makes it easy to tighten the fasteners — only one tool is required.
The curious name “80/20” is actually the brand name of the manufacturer of the extruded aluminum stock — 80/20, Inc.
Why did they choose this name? According to 80/20, they named their company and product line after Pareto’s Law (from Vilfredo Pareto (1843 – 1923)), an Italian economist and sociologist who said that 80% of your results come from 20% of your efforts.
As we all know, steel is an exceptionally strong material, but so is the aluminum used to make 80/20 extruded frames: it’s made from 6105-T5 aluminum alloy, which has a tensile strength of 35,000 lbs. per square inch.
If weight is a consideration, the 80/20 frame is considerably lighter, making it easier to move the furniture around. It can also be expedited from our factory to your location in smaller, lighter boxes, which may result in less expensive shipping costs.
However, there are some disadvantages that come from using an extruded frame system. It will take much longer to assemble the furniture when it is delivered to your site (with higher labor costs as a result), and the aluminum frame joints will need periodic maintenance over the life of the furniture to make sure the bolts are tightened to specification.
While this ongoing maintenance is not onerous, it’s one of the reasons most of our customers (especially industrial customers and those office customers looking for that ‘industrial look’) choose fully-welded steel frames. Welded steel joints don’t require any ongoing maintenance, and they are inherently stronger than bolted connections.
On the other hand, if you are already using 80/20 extruded frames then you might prefer furniture with the same construction technique. For example, some product designers, engineers, do-it-yourself (DIY) experimenters and scientists involved in prototyping, 3D printing or other experimental lab work often use 80/20 extruded frames to mount test equipment, linear stepper motors, and other devices. For these customers, having a compatible system that will allow equipment to be connected directly to the frame of Formaspace furniture might have useful advantages.
Formaspace Design Consultants provide free design services, including answering all your questions about which furniture configurations are just right for you.
Not sure about whether you should pick fully-welded steel or 80/20 aluminum extruded frames?
Give us a call today. We can explain the advantages of each system so you can make the right choice for your needs.