The Hidden Gem in Metal Fabrication: The Impact of Slots and Tabs

Last updated on December 18th, 2023 at 12:38 pm

At Approved Sheet Metal, we regularly add slots and tabs to weldment components—a process most metal fabrication shops don’t undertake.

Slot and tab features perform two critical functions:

  1. Slots & tabs enable self-fixturing, ensuring exceptional alignment during welding.
  2. Slots & tabs function similarly to cleco (or “cleko”) holes, allowing us to locate assembly components easily.

Because this process occurs behind the scenes, it often goes unnoticed by our customers. Keep reading to learn how we approach slot-and-tab design and how these features benefit your custom sheet metal parts and assemblies.

Slots and Tabs for Weldment Components 

Picture a four-sided box with flanges that are 8” high. To weld the box’s corner seams, most shops apply clamps or other fixtures to hold the sides in place at the correct angles—a time-consuming task that can double the welding time.

Adding slots & tabs to the box’s sides makes those sides self-fixturing, eliminating the need for tedious measuring and clamping by the welder. Instead, the slots and tabs snap together quickly and easily, accurately interlocking the corner seams for fast, superior-quality welding.

Now, visualize the same four-sided box but with an additional piece that slides into the center of the box. With the application of slots & tabs, the mating component will click into place with minimal effort.

With your custom sheet metal components properly aligned for welding and assembly, we can proceed with grinding smooth any weld-filled external slots and tabs.

Slots and tabs vs. fixturing

While production shops may prefer to spend time on fixturing and forego adding slots and tabs, the ASM team agrees that slot-and-tab design makes assembly faster, welding easier, and lead times shorter. Slots & tabs also eliminate any risk of distortion from improperly aligned components.

Slot-and-Tab Design Principles

You don’t need to include slots & tabs in your design for us to add them. However, should you decide to design them into your part, the experts at our metal fabrication shop recommend these best practices:


Approved Sheet Metal creates 0.25” long tabs that are 0.007” smaller than their coordinating slots on all sides. This slight wiggle room allows the tabs to fit effortlessly into their slots.

There is one consideration for custom sheet metal parts made from aluminum. Since aluminum cannot be fused like steel or stainless, the slot should be made slightly larger than 0.007” to accommodate the weld filling.


When it comes to slots & tabs, the “less is more” principle typically applies.

Seven tabs on an 8” flange: that’s overkill! Three would have done the trick—no problem.

For a flange under 2”, slots and tabs are usually unnecessary; a single slot-and-tab combination should be plenty for a flange that extends to 3” or 4”.

Designing Slots and Tabs in SOLIDWORKS

Slots and Tabs

If you’re designing slots and tabs in SOLIDWORKS, there’s no need to create these features manually. Instead, use the CAD software’s Tab and Slot option in the Sheet Metal toolbar or select Insert > Sheet Metal > Tab and Slot.

SOLIDWORKS will guide you through the process, prompting you to define the quantity and spacing of your slots and tabs before integrating them into your 3D model.

Watch the enclosed video to see the SOLIDWORKS solution in action!

Approved Sheet Metal Goes Above and Beyond

While there’s no need for any of our customers to design their own slots and tabs, we’re always happy to provide a backstage glimpse into the processes that have earned our sheet metal fabrication shop a reputation as the trusted partner for world-class innovators.

If you’d like additional insights on adding slots and tabs to your CAD models, don’t hesitate to contact us—whether or not you’re a current ASM customer.

Or request a quote and join the long list of high-performance industries that rely on ASM for their custom sheet metal services!

Metal Fabrication Slots and Tabs FAQ

Slots and tabs are specialized features added to sheet metal components. They serve two key purposes: enabling self-fixturing for precise alignment during welding and functioning as assembly locators, similar to cleco holes, to simplify component positioning during assembly.

Integrating slots and tabs into sheet metal parts allows for self-fixturing, eliminating the need for time-consuming clamping or measuring during welding. These features quickly interlock components, ensuring accurate alignment and faster, superior-quality welding, reducing both time and effort.

Slots and tabs aren't mandatory in initial designs. However, integrating them into the design is recommended for improved welding and assembly efficiency. The ASM team has expertise in adding these features if they're not initially part of the design.

The recommended dimensions involve creating tabs that are 0.25” long, slightly smaller (0.007”) than the coordinating slots. This slight tolerance ensures a snug fit. For aluminum parts, allowances for weld filling differ, requiring slightly larger slots.

Regarding quantity, the "less is more" principle applies. Overdoing tabs on a flange, for instance, isn't necessary; a few well-placed tabs are sufficient for proper alignment.

Yes, SOLIDWORKS provides a dedicated feature for designing slots and tabs within its Sheet Metal toolbar. Using this tool simplifies the integration of these features into 3D models, allowing designers to define quantity and spacing easily.

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