Reference
PEM hardware hole size chart
Recommended mounting-hole size, minimum sheet thickness, and edge distance for common self-clinching (PEM-style) nuts, studs, and standoffs.
Self-clinching hardware — commonly called PEM hardware after the original brand — is a family of nuts, studs, and standoffs that press permanently into a punched or drilled hole in sheet metal, displacing host material into a clinch groove so the fastener cannot spin or pull out. Because the fastener locks into the hole rather than threading through it, the mounting-hole size is set by the fastener, not by the screw that later mates to it. Get the hole right and the joint is strong and reusable; get it wrong and the fastener spins, backs out, or blows out the edge.
Self-clinching nuts — inch series
Recommended mounting hole and minimum host-sheet thickness for common inch-series self-clinching nuts. Values are shown as inch / mm.
| Thread size | Mounting hole (in / mm) | Min sheet thickness (in / mm) |
|---|---|---|
| 4-40 | 0.166 / 4.22 | 0.030 / 0.8 |
| 6-32 | 0.213 / 5.41 | 0.030 / 0.8 |
| 8-32 | 0.213 / 5.41 | 0.030 / 0.8 |
| 10-32 | 0.250 / 6.35 | 0.030 / 0.8 |
| 1/4-20 | 0.328 / 8.33 | 0.030 / 0.8 |
Self-clinching nuts — metric series
| Thread size | Mounting hole (mm / in) | Min sheet thickness (mm) |
|---|---|---|
| M3 | 4.22 / 0.166 | 0.8 |
| M4 | 5.41 / 0.213 | 0.8 |
| M5 | 6.35 / 0.250 | 0.9 |
| M6 | 8.33 / 0.328 | 0.9 |
Source: recommended mounting-hole and minimum-sheet-thickness values follow published self-clinching fastener installation specifications (self-clinching fastener manufacturer catalog data; Industrial Fasteners Institute standards for clinch fasteners). Recommended hole tolerance is typically +0.003 / −0.000 in. Verify every value against the specific fastener part datasheet — miniature, floating, and heavy-duty variants differ.
Studs, standoffs, and edge distance
Self-clinching studs and standoffs follow the same principle, but their mounting hole is keyed to the part’s clinch shank or barrel diameter — read it directly from the part datasheet rather than inferring it from the thread. Two rules cover almost every layout:
- Minimum sheet thickness ≈ 0.030 in (0.8 mm) for the standard series. Thinner host sheet cannot fill the clinch groove — switch fastener types below that.
- Minimum edge distance ≈ one mounting-hole diameter from the hole centerline to any sheet edge (the datasheet gives the exact figure). Closer than that and the clinch distorts or breaks out the edge.
How to read the chart
Pick the fastener size, take its mounting-hole diameter, and put that hole on the flat pattern — not the thread size. Confirm the host sheet meets the minimum thickness and that every fastener sits at least one hole-diameter from an edge and from its neighbors. Then hold the hole to the recommended tolerance (a punched or laser-cut hole at ±0.1 mm is well inside it) and keep the install side free of chamfers and burrs.
Common mistakes
- Sizing the hole to the screw. The hole matches the clinch body, which is larger than the thread. A tap-drill-sized hole will not accept the fastener.
- Chamfering the mounting hole. Self-clinching hardware needs a clean, square hole on the install side. A countersink or heavy burr stops it from seating flush.
- Clinching into too-thin or too-hard sheet. Below about 0.8 mm, or into work-hardened stainless, a standard fastener will not hold.
- Crowding the edge. Fasteners set too near an edge or a bend deform the sheet instead of locking in.
Where this fits our shop
Hardware insertion is in-house at Nevatronix Sheet Metal — self-clinching nuts, studs, standoffs, and captive screws installed on a clinch-rated press, plus insertion within our finishing and coating flow when the sequence calls for it. Punch the mounting holes first — the gauge chart confirms the host stock meets the 0.8 mm minimum.
Frequently asked questions
- What size hole do I need for a self-clinching (PEM) nut?
- The mounting hole is set by the fastener size, not the thread you are tapping into it. For common inch self-clinching nuts the recommended hole is 0.166 in (4.22 mm) for 4-40, 0.213 in (5.41 mm) for 6-32 and 8-32, 0.250 in (6.35 mm) for 10-32, and 0.328 in (8.33 mm) for 1/4-20, typically to a +0.003 / −0.000 in tolerance. Punch or drill the hole clean and round — a chamfer or burr on the install side prevents the fastener from seating and clinching.
- What is the minimum sheet thickness for self-clinching hardware?
- Standard-series self-clinching nuts, studs, and standoffs need a host sheet of at least about 0.030 in (0.8 mm) so there is enough material to flow into the clinch groove. Below that, the clinch will not hold reliably and you should switch to a floating, surface-mount, or through-bolted fastener. Our documented sheet range starts at 0.02 in (0.5 mm), which is thinner than the self-clinch minimum — so on very thin stock we will recommend an alternative.
- How far from the edge can a self-clinching fastener sit?
- Keep the hole centerline at least one mounting-hole diameter from any sheet edge as a rule of thumb; the exact minimum edge distance is listed on each fastener’s datasheet. Too close to the edge and the displaced material bulges or blows out the edge instead of locking the fastener in. When a fastener must sit near an edge, the datasheet minimum governs — design to it, do not average it.
- Can you install self-clinching hardware into stainless steel or hardened sheet?
- Only with the right fastener. A self-clinching fastener has to be harder than the sheet it displaces, so standard steel and aluminum fasteners install into soft steel and aluminum (roughly HRB 88 or softer) but will not clinch into work-hardened stainless or spring-tempered stock. Hardened stainless hosts need a fastener rated for stainless. Tell us the host material and we will match the fastener.
- Do you install PEM hardware in-house?
- Yes. Hardware insertion — self-clinching nuts, studs, standoffs, and captive screws — runs on a self-clinch-rated press as part of our assembly and finishing workflow, installed before or after finishing per the print. See our assembly page for the full hardware-insertion and kitting scope.
Hardware on the print? We insert it in-house.
Send the assembly with the fastener callouts. We punch the holes, insert the clinch hardware, and ship it assembled and inspected — one PO, one quality record.