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// Self-Clinching Fasteners

Hardware
Size Chart

A pressed nut puts a real thread in sheet too thin to tap — if the sheet will let it clinch.

Hole size, outer diameter, and part numbers for every self-clinching fastener we stock: nuts, flush nuts, studs, standoffs, and blind standoffs, in steel and stainless. Pick your sheet material and gauge and the whole catalogue marks itself — because a clinch needs two things the fastener chart never tells you, enough thickness to bite and a sheet softer than the fastener.

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Hardware Types
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Catalog Parts
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Min. Sheet
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Hole Tolerance
// Will It Clinch? Live

Every option is a thickness we actually stock, straight from the material catalog.

// Verdict
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// Hardware Catalog

Every fastener we press.

Five families, in zinc-plated carbon steel and stainless. The hole size column is the one that decides whether the part seats — it is specific to the part number, held to ±0.002″, and it is not the clearance or tap drill for the same thread. The materials dropdown on each row lists the sheet it will clinch into at your selected gauge.

Units
Threads

// Why a Clinch Fails

Two things have to be true, and neither is on the fastener chart.

A self-clinching fastener works by displacing your sheet into an undercut in the fastener. That one sentence contains both limits.

1

The sheet has to be thick enough to displace.

Below 0.040″ — about 22 gauge — there is not enough parent material to fill the undercut, and nothing in the catalog will hold, at any thread size. Above that the floor rises with the thread: our smallest sizes clinch at 0.040″, and by M6 you need about 0.093″.

Between those two figures it depends on the specific part number, which is why this chart says confirm rather than guessing for you. Send the part or the thread size on your quote and we will check it against the datasheet.

2

The fastener has to be harder than the sheet.

The knurl only clinches if it can cut and displace parent material. When the sheet is as hard as the fastener, the fastener deforms instead and you get a part that spins in the hole.

This rules some of our catalog out entirely. AR500 at roughly 500 BHN and hardened spring steel are both harder than any self-clinching part — they cut and bend fine, but they will not take hardware. MIC-6 cast plate fails for a different reason: the cast structure will not form a sound clinch.

And it makes one common pairing a bad idea: 303/304 stainless hardware into 304 or 316 stainless sheet. Same alloy family, so the hardness gap the clinch depends on is not there. Use zinc-plated steel hardware, a hardened stainless series, or a through-bolt — and mind the dissimilar-metal contact if the assembly gets wet. Switch the hardware material in the selector above and the chart will flag it.

// Compatibility Matrix

Thread size against every sheet we stock.

Each column is an alloy family from our catalog; each row is a thread size. The cell answers both gates at once, at the gauge selected in the card above. Change the gauge and the whole grid moves.

// Designing For It

Four things to get right in CAD.

Hardware is cheap to add and expensive to fix after the fact, because it goes in before forming and finishing. These are the decisions that have to be made in the model.

01
Model the mounting hole at the hardware size, not the thread size.
A #6-32 PEM nut wants a 0.188″ hole. The tap drill for the same thread is 0.106″ and the clearance hole is 0.144″ — neither will clinch. Take the number from the hole-size column above, and hold ±0.002″. Oversize is the common failure: the part goes in and then spins.
02
Name the install side.
Standard nuts and studs protrude on the side they are pressed from, and studs stand off it entirely. Mark near side or far side as the part sits nested, and check the protrusion clears whatever sits against that face in the assembly. A flush nut avoids the question by finishing level with both faces — at the cost of the tightest hole tolerance in the catalog.
03
Keep hardware clear of bend lines.
Hardware goes in before forming wherever the press brake allows, because pressing into a formed part often has no access. A fastener too close to a bend line fouls the tooling, so it either moves or gets installed after forming as a separate operation. If a hole must sit near a bend, flag it — the same keep-out logic as the hole-to-bend distance guide.
04
Decide the finish order.
Hardware is always installed before powder coat or anodize, so the threads get masked rather than coated. If you need a coated part with clean bare threads, that is the normal path. If you need the fastener itself uncoated for grounding or conductivity, say so on the quote — and remember the clinch breaks any pre-existing plating on galvanized sheet right at the fastener.
// Common Questions

Hardware, answered.

What people ask most about pressed fasteners in sheet metal, and where the limits actually are.

What is the minimum sheet thickness for self-clinching hardware?
0.040″ — about 22 gauge — for the smallest threads like #4-40 and M3. Larger threads need more material, up to about 0.093″ for M6. Below 0.040″ the clinch has nothing to bite and no self-clinching part will hold: use a through-bolt, or step up a gauge. Converting gauge numbers to decimals? See the gauge chart.
Which sheet materials can take PEM hardware?
We install into aluminum 5052 and 6061, steel A1008 and A36, and stainless 304 and 316. The governing rule is that the fastener must be harder than the sheet, because the knurl has to displace parent material into its undercut. That rules out AR500 and hardened spring steel completely, and rules out MIC-6 cast plate for structural reasons. Anything else in our catalog, ask — the matrix above marks each family.
Can you put stainless PEM hardware into stainless sheet?
Not reliably with 303/304 parts. Standard stainless self-clinching hardware is 300-series — the same family as 304 and 316 sheet — so the two are too close in hardness for the clinch to form. Use zinc-plated steel hardware, a hardened stainless series, or a through-bolt. If you go with steel hardware in stainless sheet, mind the dissimilar-metal contact in a wet environment.
What hole size does PEM hardware need?
An exact size, specific to the part number, at ±0.002″. The clinch works by displacing a controlled amount of sheet, so an oversize hole leaves the part free to spin and an undersize hole will not seat. It is not the clearance hole and not the tap drill. A #6-32 PEM nut takes 0.188″; the tap drill for #6-32 is 0.106″ and the free-fit clearance is 0.144″. Compare against the tap and clearance chart.
When should I use a PEM nut instead of tapping the sheet?
Whenever the sheet is too thin to hold a thread you would trust. In flat sheet the engagement length is the thickness, so a tapped hole has to clear two full threads of pitch and half the screw diameter — at 16 gauge only a #4-40 clears both. A pressed nut moves the load into a flange much larger than the hole, which is why it works in gauges where tapping does not. The tap chart checks the tapping side for you.
Is hardware installed before or after bending?
Before, wherever the press brake tooling allows — and always before powder coat or anodize. A fastener already in the sheet can foul the tooling on a nearby bend, so hardware close to a bend line either moves or gets installed after forming as a separate operation. Hardware adds no lead time to our standard production cycle either way.
What is the difference between a standoff and a blind standoff?
A standard standoff (SO) is through-threaded, so a screw can enter from either end. A blind standoff (BSO) has a solid cap and takes a screw from the install side only. Choose blind when only one end is ever used, or when debris or liquid would foul an open thread — outdoor and washdown assemblies especially. Hole size is identical between the two for a given thread.
PEM nut or flush nut?
A standard nut protrudes slightly on the install side, so that face needs clearance. A flush nut finishes level with both faces — necessary when panels stack or a mating surface must stay flat. The tradeoff is accuracy: a flush nut's outer diameter sits very close to its hole size, making it the least forgiving part in the catalog. Note the F series is steel only; there is no stainless flush nut.
Where do these numbers come from?
Hole sizes, outer diameters, and part numbers are our own catalog, shared with the hardware pages and the insertion guide. Hole sizes vary between PEM series, so do not cross them with another shop's chart — the same thread can want a different hole. The two thickness anchors (0.040″ smallest, 0.093″ all sizes) are the published figures from our insertion tech data and the DFM rule for quote code 3008. Where a size falls between them this chart says confirm rather than interpolating a number nobody published.
Hardware picked?Flag the holes on your quote and we press it before forming.
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