Insert hardware is one of those fabrication and manufacturing secrets that you’ve likely heard of, maybe even used, but may not fully understand the value and capabilities offered by SendCutSend. In this article we’ll walk through some critical things to know including
- The value in using PEM hardware
- Guidelines when designing parts using PEM hardware
- Some example use cases
- Sizes and styles of PEM hardware you can get pre-installed in your parts directly from SendCutSend
If you stumbled across this article looking for hardware specs, you can find them here, in our hardware catalog. You can also check out our Hardware Insertion Service page.
What Is Insert Hardware for Sheet Metal?
Insert hardware is a family of hardware that is typically pressed into a part (sheet metal is most common) to provide a method of connection. That may take the form of a female threaded nut or male threaded stud, but other varieties also exist like pins. SendCutSend offers three types, nuts, studs and standoffs, more on that further down.
High quality insert hardware is most often associated with the brand PEM, which is the brand of insert fasteners developed by PennEngineering. This is what SendCutSend uses.
Why Use Hardware Inserts in Sheet Metal?
Why use PEM hardware in your parts? Let’s look at a few reasons in detail.
Some Materials Shouldn’t Be Tapped
Often when threaded fasteners are being used in fabrication, materials get tapped directly allowing a screw to be threaded in place. This is a great option in a lot of cases, but what if your material is too thin to thread sufficiently? Insert hardware, that’s what. Insert hardware is used almost exclusively with sheet metal for this very reason.
Tool Access/Blind Assembly
If the material is too thin for adequate threads, why not just use a nut on the back side? Sometimes you don’t have access to the back side to hold onto a nut with a wrench. Think of an access panel bolted onto an enclosure. Unless you plan to train a squirrel to live inside the enclosure and hold the nuts while you tighten the bolts, insert hardware is the way to go.
Save Time at Assembly
Let’s say you do have access to the back side for a nut and a wrench to hold it. You can still save time (potentially cutting costs) during assembly by having insert hardware installed and not needing to deal with the back side at all. This is especially true when multiple components get stacked up using the same fasteners. Threaded studs work great by allowing you to loosely hold or hang everything in position while you tighten the nuts. If you’ve ever tried to hold a heavy or awkwardly shaped part against a vertical surface while trying to align holes to get bolts in place, you understand the benefit of threaded studs.
No-weld/Non-permanent Fixturing
Insert hardware can be a great option for building fixtures that don’t need to be welded. Threaded studs can be used to hold parts using existing holes. Quick-change, modular tooling can make configuration changes
- Cheaper utilizing insert hardware in thinner sheet metal vs threaded holes in thicker materials
- Faster utilizing insert hardware to eliminate the need to hold fasteners from both sides
Controlled Spacing
Sometimes you need to assemble components together, but keep a clearance between them. This is typical with electronics where PCBs need to be securely mounted, but can only make contact in specific areas to avoid shorting. This is a perfect application for standoffs or even studs with separate spacers.
General Design Guidelines for Insert Hardware in Sheet Metal
You can find all our design guidelines here, but we’ll illustrate a few below.
Materials
We can install PEM hardware into aluminum (excluding 2024), steel (both mild and G90) and stainless steel (both 304 and 316), but thickness matters too so be sure to check the specs on the size of insert you want to use. You can find the range of material thicknesses listed for each size insert on the spec sheet.
Orientation
When including insert hardware in your design, you’ll need to decide which side of the sheet to install the fastener. With studs and standoffs this should be fairly obvious, but with nuts you’ll want to take a closer look. While nuts are threaded all the way through, you’ll want to make sure they get installed on the opposite side of the panel that the bolt will be pulling from. The nut will be significantly stronger in this direction since the bolt would have to pull through the panel to fail.
You’ll indicate which side the insert is installed from during the order process as you select the sizes of hardware you want.
Clearances to Nearby Features
Because we use unique tooling to install PEM hardware into your parts, there needs to be a minimum amount of clearance to nearby features. This includes edges of panels, other PEM inserts and bends.
Clearances to edges and other hardware can be found listed in the specs for each different size insert.
Clearances around bends depend on the bend radius of the material itself, so that information is located in the material specs, under the Hardware Specifications section.
The examples from above (¼-20 nut insert in .063” thick 5052 aluminum) can be interpreted as follows in your design:
Distance C/L to edge: .340”
Distance C/L to C/L of adjacent holes: .512”
Distance C/L to bend line: .425”
Examples of Insert Hardware in Sheet Metal
Standoffs
Here standoffs have been installed to keep the PCB from contacting the enclosure.
Nuts
In the same example, nuts have been installed along the sides of the inner half of the enclosure. Matching clearance holes along the outer half of the enclosure allow screws to be installed securing the two halves together.
Studs
We mentioned previously that studs can be useful when multiple components are assembled using the same set of fasteners. In this example four studs have been installed in the lower half of the enclosure allowing for a stack of spacers, the PCB, a set of threaded spacers, followed by the upper half of the enclosure and finally a set of screws to lock everything in place. Try assembling that as cleanly with standard nuts and bolts.
What Hardware Does SendCutSend Offer?
SendCutSend does not offer the full PEM hardware catalog, but we do offer studs, nuts and standoffs, which tend to be the most commonly used. For full details, you can visit our PEM hardware catalog.
We offer both metric and imperial sizes.
| Nuts | Standoffs | Studs |
| Imperial Sizes | ||
| 4-40 | 4-40 x .250, .375 and .500 | 4-40 x .250, .375, .500 and .625 |
| 6-32 | 6-32 x .250, .375, .500 and .625 | 6-32 x .250, .375, .500 and .625 |
| 8-32 | 8-32 x .250, .375 and .500 | 8-32 x .250, .375, .500 and .625 |
| 10-32 | 10-32 x .250, .375 and .500 | 10-32 x .375, .500, .625 and .75 |
| 1/4-20 | 1/4-20 x .375, .500, .625, .75 and 1.00 | |
| 5/16-18 | ||
| 3/8-16 | ||
| Metric Sizes | ||
| M3 | M3 x 6mm, 10mm and 12mm long | M3 x 6mm, 8mm, 10mm and 12mm long |
| M4 | M4 x 6mm, 10mm and 12mm long | M4 x 6mm, 8mm, 10mm and 12mm long |
| M5 | M5 x 6mm, 10mm and 12mm long | M5 x 8mm, 10mm and 12mm long |
| M6 | M6 x 12mm and 20mm long | |
| M8 | M8 x 12mm and 25mm long | |
Putting PEM Insert Hardware in Sheet Metal to Use for You
We hope this information regarding PEM insert hardware in sheet metal has helped you get a better feeling for what insert hardware is and how it can be used in your next SendCutSend project. We’ve really only scratched the surface in this guide. If you’d like a bit more in depth look at this hardware, including how to import the PEM library into your CAD software, we have another article you can read here.We’d love to see your projects utilizing insert hardware. Get instant pricing and explore how easy it is to include PEM fasteners in your parts.
