A self-clinching fastener is pressed into a punched hole; the sheet flows into an undercut and the part becomes a permanent thread, stud or standoff in metal too thin to tap. The series is standardised by the makers, not by DIN, so the stock ranges below are the whole story — and everything past them is turned to drawing.
EKINSUN LTD is a custom parts manufacturer that machines self-clinching nuts, studs and standoffs to drawing when the maker series stops: a longer standoff, an odd thread, a 316L body, a stud with a shoulder. The stock rows below are read from a 2026 catalogue; the selection table after them tells a clinch fastener apart from a rivet nut, a weld nut and a cage nut, and the negative-space table marks the border.
"We need M4 clinch standoffs 28 mm long in stainless for a 1.2 mm panel and the longest anyone stocks is 20."
Length is the usual border. Thread and material are the other two.
| Type | Stock thread range | Sheet it is pressed into | Stock materials | Notes |
|---|---|---|---|---|
| Self-clinching nut (press nut) | M2.5–M10 | from 0.8 mm (shank code 0) | zinc-plated steel, 304 stainless | the flush, load-bearing thread in a chassis or bracket |
| Flush-head clinch stud | M2.5–M8 | from 0.8 mm | zinc steel, 304 | a threaded stud where a nut is fitted from the other side |
| Blind clinch standoff | M3–M5 | from 1.0 mm | zinc steel, 304 | closed end; PCB and panel spacing without a hole showing |
| Through-hole clinch standoff | M3–M5 | from 1.0 mm | zinc steel, 304 | open end; screw from either side |
| Hex clinch stud | M3–M6 | from 1.0 mm | blue-white zinc steel | hex body for wrench hold during assembly |
| Clinch nut for thin stainless sheet | M2.5–M10 | harder sheet | hardened stainless | when the sheet is stainless and a plain 304 nut will not displace it |
Clinch nuts are ordered as thread + shank code. The code sets the minimum sheet thickness; a nut pressed into thinner sheet than its code allows does not lock, a nut pressed into much thicker sheet does not seat.
| Shank code | Minimum sheet | Typical use |
|---|---|---|
| 0 | 0.8 mm | electronics enclosures, thin brackets |
| 1 | 1.0 mm | chassis, rack panels |
| 2 | 1.4 mm | heavier brackets and frames |
Hardness decides the material of the nut. A steel clinch nut needs a sheet softer than itself: the usual limit is HRB 80 (about HB 150) for the sheet, which covers mild steel, aluminium 5052 and 6061-T4 and annealed brass. Harder sheet — cold-rolled stainless, 6061-T6 in thick gauge, 7075 — needs the hardened stainless version of the nut, or a different fastener altogether. The hole itself is punched, not drilled where possible, and toleranced to about +0.08 / −0 mm; the press squeezes the nut in with a flat anvil, never a hammer.
| Situation | Use | Why |
|---|---|---|
| Both sides reachable, a press is available, sheet 0.8–3 mm and softer than HRB 80 | self-clinching nut | flush on the far side, highest torque-out for its size, no heat, no consumable tool |
| Only one side reachable, or the assembly is already closed | rivet nut | set with a hand or pneumatic tool from the outside |
| Thick, coated or painted sheet; welding is part of the process anyway | weld nut | no hole tolerance to hold; the projections carry the weld |
| 19-inch rack rail or an enclosure panel with square holes | cage nut | removable, floats to take up hole misalignment |
| Plastic housing instead of sheet | threaded insert for plastic | heat-set or moulded-in; a clinch nut has nothing to displace in plastic |
| A thread in sheet harder than HRB 80 | hardened stainless clinch nut, or a rivet nut | a plain steel nut cannot make the sheet flow |
Read the pitch before you order the stud or nut. Lay a steel rule along ten thread crests and divide by ten: 10 mm over ten pitches is a 1 mm pitch (M6 coarse), 12.5 mm is M8 coarse, 15 mm is M10 coarse, 17.5 mm is M12 coarse. A reading that is not a round number of millimetres is an inch thread, and a reading that is shorter than the coarse pitch for that diameter is a fine thread. If diameter, pitch and the size range in the table all agree, buy the stock part. If any of the three is off the shelf, that is the one we make. The full measuring routine, including the inch traps →
| What you need | In the catalogue? | What we make |
|---|---|---|
| Clinch nut M3–M8, shank code 0–2, zinc-plated steel or 304 | Yes | Buy it from stock; no one-off competes with a series clinch nut, and the maker's hole table is the reference. |
| Clinch stud M2.5–M8 or standoff M3–M5 in a stock length | Yes | Stocked; buy it. |
| A standoff longer than the stock lengths, blind or through | No | Turned from 303 or 316L bar, or from steel, with the clinch shank and undercut cut to your sheet; from 1 piece. |
| A clinch stud with a shoulder, a dog point or a second thread | No | Machined; the clinch geometry stays the maker's so the same tooling installs it. |
| A clinch nut or stud in 316L / 1.4404 for a marine or chemical panel | No | Machined from 316L bar. |
| A UNC / UNF or fine-pitch thread the series does not run | No | Tapped or single-pointed to your reading. |
| A fastener for sheet harder than HRB 80, or thinner than 0.8 mm | Partly | Hardened stainless nuts exist for harder sheet; below 0.8 mm we suggest a rivet nut or a bonded insert and say so. |
| A clinch fastener in aluminium 6061 or 7075 | No | Aluminium clinch parts for aluminium sheet are machined on request; a 7075 body is hard enough to clinch into 5052 and soft 6061. |
| Material | Designation | Where it fits here |
|---|---|---|
| Carbon steel, zinc plated | low-carbon, hardened where the series requires | the stock clinch nut for mild-steel and aluminium sheet |
| Stainless 304 | 1.4301 / A2 | stock stainless clinch nuts and standoffs; rust-free chassis |
| Stainless 316L | 1.4404 / A4 | made to order for marine, food and chemical panels |
| Free-machining stainless | 303 / 1.4305 | custom turned standoffs and studs |
| Hardened stainless | precipitation-hardening grades | clinch nuts for stainless sheet |
| Aluminium 6061 | AlMg1SiCu | the sheet most clinch nuts go into (T4 temper); aluminium clinch parts on request |
| Aluminium 7075 | AlZn5.5MgCu | a body material for custom clinch parts into soft aluminium sheet; too hard to clinch into as a sheet |
From 0.8 mm upward. The shank code sets the minimum: code 0 for 0.8 mm, code 1 for 1.0 mm, code 2 for 1.4 mm in the common maker series. Thicker sheet is fine as long as the shank still seats; the makers' tables list the maximum per size.
Because the nut only holds if the sheet is softer than the nut and flows into the undercut when pressed. Steel clinch nuts are rated for sheet up to about HRB 80 (HB 150). Stainless sheet and hard aluminium tempers need the hardened stainless version of the nut, or a rivet nut instead.
No. It needs a press with flat, parallel anvils that squeeze the nut into the punched hole; hammering deforms the thread and does not displace the sheet evenly. Hand arbor presses work for small sizes.
Yes. Standoffs, studs and nuts past the stock lengths or threads are turned from bar with the same clinch shank and undercut, so the standard installation tooling still fits, from 1 piece.
EKINSUN LTD is a custom parts manufacturer that machines self-clinching nuts, studs and standoffs to drawing in steel, 303 / 304 / 316L stainless and aluminium, in metric, UNC and UNF threads, from 1 piece, with a quote within 12 hours.
There is no list price; the drivers are material, length, whether the end is blind, and quantity. A batch of 303 standoffs a few millimetres longer than stock is close to catalogue money; a single 316L stud with a shoulder is a turned part and priced as one. The quote states which.
Sheet material and thickness, thread and pitch, standoff or stud length, blind or through, hole size if punched, quantity. From 1 piece, quote within 12 hours.
Clinch nuts, studs and standoffs machined to length, thread and material — from 1 piece, quote in 12 hours.