PEM (Penn Engineering) self-clinching hardware is the standard for sheet metal assemblies needing threaded features. A press-in fastener forms a permanent mechanical lock into the sheet — higher pullout strength than welded nuts, faster than tapped threads, more reliable than self-tapping screws. We maintain a full PEM catalog and insert with calibrated presses.
| Method | Pullout force | Cost per feature | Best for |
|---|---|---|---|
| PEM press-in | High — 8–15 kN typical M5 | $0.30–$1.50 | Standard sheet assemblies, volumes 100+ |
| Weld nut | Very high — 12–25 kN | $0.80–$3 | Heavy-duty structural, thick sheet (>4 mm) |
| Tapped thread in sheet | Low — limited thread engagement | $0.50–$1 | Rare — only if sheet >1.5× thread diameter |
| Self-tapping screw | Low — one-time assembly | Included in fastener | Non-removable assemblies, thin sheet |
| Rivet nut (rivnut) | Medium — 4–8 kN | $0.50–$1.50 | Blind-side sheet access, field repair |
Each PEM part number has a specific mount hole diameter (slightly smaller than insert OD). Deviate by more than 0.05 mm and insertion fails or produces weak lock. Use PEM tables — don't estimate.
Each insert has a minimum sheet thickness (typically 0.8–1.5 mm). Thinner sheet deforms during insertion without locking.
PEM hardware requires 2× diameter from any edge or 1.5× from another insert. Closer placement causes sheet buckling during press.
PEM inserts install flat. If the sheet has bends near the insert location, install before bending. Bent sheet distorts the press seat.
PEM part number (e.g., CLS-M5-2) unambiguously specifies thread, sheet thickness range, and material. "M5 nut" alone doesn't.
Upload STEP with PEM part numbers called out. We stock the standard catalog and press on calibrated equipment.
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