| Thread | D | T | L | d₁ | t₁ |
|---|---|---|---|---|---|
| M2 | 4.8 | 0.43 | 3.9 | 3.2–3.3 | 2.4 min |
| M2.5 | 5.5 | 0.51 | 4.7 | 4.0–4.1 | 3.2 min |
| M3 | 5.5 | 0.51 | 4.7 | 4.0–4.1 | 3.2 min |
| M3.5 | 6.4 | 0.66 | 6.3 | 4.8–4.9 | 3.6 min |
| M4 | 7.1 | 0.82 | 7.9 | 5.6–5.7 | 4.0 min |
| M5 | 7.9 | 1.00 | 9.4 | 6.4–6.5 | 4.8 min |
| M6 | 9.5 | 1.25 | 12.6 | 8.0–8.1 | 6.0 min |
| M8 | 11.1 | 1.25 | 12.6 | 9.6–9.7 | 7.0 min |
| Thread | D | T | L | D₁ | d₁ | t₁ |
|---|---|---|---|---|---|---|
| M2 | 4.8 | 0.43 | 3.9 | 3.2 | 3.2–3.3 | 2.4 min |
| M2.5 | 5.5 | 0.51 | 4.7 | 4.0 | 4.0–4.1 | 3.2 min |
| M3 | 5.5 | 0.51 | 4.7 | 4.0 | 4.0–4.1 | 3.2 min |
| M3.5 | 6.4 | 0.66 | 6.3 | 4.7 | 4.8–4.9 | 3.6 min |
| M4 | 7.1 | 0.82 | 7.9 | 5.5 | 5.6–5.7 | 4.0 min |
| M5 | 7.9 | 1.00 | 9.4 | 6.3 | 6.4–6.5 | 4.8 min |
| M6 | 9.5 | 1.25 | 12.6 | 7.9 | 8.0–8.1 | 6.0 min |
| M8 | 11.1 | 1.25 | 12.6 | 9.5 | 9.6–9.7 | 7.0 min |
| Thread | D | L | d₁ | t₁ |
|---|---|---|---|---|
| M2 | 3.2 | 3.9 | 3.2–3.3 | 2.4 min |
| M2.5 | 4.0 | 4.7 | 4.0–4.1 | 3.2 min |
| M3 | 4.0 | 4.7 | 4.0–4.1 | 3.2 min |
| M3.5 | 4.7 | 6.3 | 4.8–4.9 | 3.6 min |
| M4 | 5.5 | 7.9 | 5.6–5.7 | 4.0 min |
| M5 | 6.3 | 9.4 | 6.4–6.5 | 4.8 min |
| M6 | 7.9 | 12.6 | 8.0–8.1 | 6.0 min |
| M8 | 9.5 | 12.6 | 9.6–9.7 | 7.0 min |
| Thread | D | T | L | D₁ | d₂ | d₃ |
|---|---|---|---|---|---|---|
| M2.5 | 6.0 | 0.58 | 6 | 4.5 | 4.0–4.1 | 4.1–4.4 |
| M3 | 6.5 | 0.58 | 6 | 5.0 | 4.5–4.6 | 4.6–4.8 |
| M3.5 | 7.5 | 0.75 | 8 | 6.0 | 5.3–5.4 | 5.5–5.7 |
| M4 | 8.0 | 0.90 | 8 | 6.5 | 5.8–5.9 | 6.0–6.2 |
| M5 | 9.5 | 1.05 | 10 | 8.0 | 7.1–7.2 | 7.3–7.6 |
| M6 | 12.0 | 1.32 | 14 | 10.0 | 8.6–8.8 | 9.0–9.4 |
| M8 | 14.0 | 1.32 | 15 | 12.0 | 10.6–10.8 | 11.0–11.4 |
| M10 | 16.0 | 1.60 | 18 | 14.0 | 12.6–12.8 | 13.0–13.4 |
| Thread | D₁ | L | d₂ | d₃ |
|---|---|---|---|---|
| M2.5 | 4.5 | 6 | 4.0–4.1 | 4.1–4.4 |
| M3 | 5.0 | 6 | 4.5–4.6 | 4.6–4.8 |
| M3.5 | 6.0 | 8 | 5.3–5.4 | 5.5–5.7 |
| M4 | 6.5 | 8 | 5.8–5.9 | 6.0–6.2 |
| M5 | 8.0 | 10 | 7.1–7.2 | 7.3–7.6 |
| M6 | 10.0 | 14 | 8.6–8.8 | 9.0–9.4 |
| M8 | 12.0 | 15 | 10.6–10.8 | 11.0–11.4 |
| M10 | 14.0 | 18 | 12.6–12.8 | 13.0–13.4 |
Recommended boss-hole diameters and depth for post-mould installation, drawn from established insert-design references. Insert body OD and length are made to your drawing — there is no ISO/DIN dimensional standard for heat-set, press-in or self-tapping insert bodies (only the internal thread is standardised), so we build to your print or our tri-lobe series. Hole and boss geometry, however, follow well-established design rules — published here.
| Thread | Hole Ø heat-set | Hole Ø press-in | Min. hole depth | Boss OD rule | Body OD |
|---|---|---|---|---|---|
| M2 | 3.2 mm | 3.2 mm | L + 2 pitches | 2–3× insert Ø | to drawing |
| M3 | 4.0 mm | 3.95 mm | L + 2 pitches | 2–3× insert Ø | to drawing |
| M3.5 | 4.8 mm | 4.7 mm | L + 2 pitches | 2–3× insert Ø | to drawing |
| M4 | 5.6 mm | 5.55 mm | L + 2 pitches | 2–3× insert Ø | to drawing |
| M5 | 6.4 mm | 6.35 mm | L + 2 pitches | 2–3× insert Ø | to drawing |
| M6 | 8.0 mm | 7.9 mm | L + 2 pitches | 2–3× insert Ø | to drawing |
| M8 | 9.6 mm | 9.5 mm | L + 2 pitches | 2–3× insert Ø | to drawing |
| M10 | on request | on request | L + 2 pitches | 2–3× insert Ø | to drawing |
| Thread | Hole Ø heat-set | Hole Ø press-in | Min. hole depth | Boss OD rule |
|---|---|---|---|---|
| #2-56 | 0.126–0.127″ | 0.124″ | L + 2 pitches | 2–3× insert Ø |
| #4-40 | 0.157–0.158″ | 0.155″ | L + 2 pitches | 2–3× insert Ø |
| #6-32 | 0.188–0.189″ | 0.186″ | L + 2 pitches | 2–3× insert Ø |
| #8-32 | 0.221–0.223″ | 0.217″ | L + 2 pitches | 2–3× insert Ø |
| #10-24/32 | 0.252–0.253″ | 0.249″ | L + 2 pitches | 2–3× insert Ø |
| 1/4-20 | 0.315″ | 0.311″ | L + 2 pitches | 2–3× insert Ø |
| 5/16-18 | 0.377″ | 0.374″ | L + 2 pitches | 2–3× insert Ø |
| 3/8-16 | on request | on request | L + 2 pitches | 2–3× insert Ø |
Heat-set/ultrasonic hole Ø is the convergent value across established insert-design references (M2–M6 agree within ~0.05 mm); M8 and press-in small sizes are single-reference. Body OD and length are proprietary/made-to-drawing — no industry dimensional standard exists. For filled resins, open the hole (see design rules below). M10 and 3/8-16 holes, and press-in force, are provided on request against your resin and boss.
| Boss outer Ø | 2–3× insert Ø (≈2–2.5× hole Ø); the multiplier shrinks as the insert grows |
| Boss min. wall | 50–100% of insert Ø around the insert; min boss OD = insert OD + 2× wall |
| Hole depth | Insert length + 2 thread pitches (heat-set, press-in, mould-in); ≥1.2× length for self-tapping |
| Flush install | Top flush to the surface, max +0.13 mm (0.005″) proud; never sub-flush (jack-out risk) |
| Lead-in taper | Straight hole ≤1° included; tapered hole 8° included (with a tapered insert only) |
| Filler ≥ 15% | Increase the hole Ø by 0.08 mm (0.003″) |
| Filler ≥ 35% | Increase the hole Ø by 0.15 mm (0.006″); interpolate between |
| Headed counterbore | Ø = head Ø + 0.5–1.3 mm (0.02–0.05″), depth = head thickness |
| Moulded vs drilled | Moulded holes out-perform drilled (denser skin); through-hole part thickness > insert length |
| Thermosets | Cannot be heat-set — use mould-in, press-in or self-tapping |
Oversize holes cut pull-out and torque; undersize holes crack the boss. As much as ~75% of an insert’s achievable performance comes down to how well it is installed.
| Resin | Melt / processing (unfilled) | Unfilled tip rule | Filled tip rule |
|---|---|---|---|
| PA6 | melt ~215–225 °C; proc. ~240–280 °C | softening + 28 °C | softening + 83 °C |
| PA66 | melt ~255–265 °C; proc. ~270–300 °C | ||
| ABS | ~200–250 °C processing | ||
| PC | ~280–320 °C | ||
| PP | melt ~160–170 °C; proc. to ~200–250 °C | ||
| POM | ~163 °C (copolymer) to ~205–225 °C (homopolymer) |
| Thread | Unfilled (N) | 30% GF nylon (N) |
|---|---|---|
| M2 | 250–1,150 | 400–900 |
| M3 | 350–2,900 | 1,300–2,300 |
| M4 | 900–4,000 | 1,600–3,900 |
| M5 | 1,200–6,800 | 3,800–7,000 |
| M6 | 1,700–9,200 | 4,300–8,400 |
| M8 | 3,300–13,900 | 6,700–11,800 |
| Thread | Unfilled (Nm) | 30% GF nylon (Nm) |
|---|---|---|
| M2 | 0.3–1.2 | ~0.9 |
| M3 | 0.5–5 | 3.5–4 |
| M4 | 2–10 | 7–7.5 |
| M5 | 5–16 | 13–20 |
| M6 | 7–26 | 15–25 |
| M8 | 18–39 | 34–48 |
Indicative typical performance only — drawn from correctly installed heat-set/ultrasonic inserts in representative engineering thermoplastics, as a general design guide. Actual performance depends heavily on your resin and filler, hole and boss geometry, and installation process. Always validate on your own boss, resin and process; contact us for application-specific data. Values are ranges, not spec numbers. Note: glass fill does not reliably raise heat-set pull-out — it mainly raises torque-out, stiffness and creep resistance. Imperial pull-out/torque-out and the 1/4-20 glass-filled figures are on the imperial reference chart / on request. Mould-in inserts behave differently — see DIN 16903.
Expansion inserts install cold — the fingers grip the pilot-hole wall as the bolt is driven, so no press, heat or special equipment is needed; ideal for field assembly and thermosets. Knurled threaded inserts give higher pull-out and torque and are pressed, moulded-in or ultrasonically installed. For self-tapping, foam-grade and barbed press-in types see our cold-installation range, or start with the selection guide.
Standard coverage runs M2 to M10 ISO metric and #2-56 to 3/8-16 UNC, in headed, reverse-head and unheaded styles. Internal threads are produced to ISO 965-1 tolerance class 6H. Custom lengths, knurl patterns and thread sizes are made to drawing.
Inserts are machined from CW614N (CuZn39Pb3) free-cutting brass rod per EN 12164, RoHS and REACH compliant. Nickel, tin and zinc plating options are available on request — see our CW614N datasheet and surface finishes guide.
Yes — free samples are available for evaluation. All production is made to order; send your drawing or a competitor part number and we’ll confirm the equivalent, with pricing and lead time within one business day.
For unfilled thermoplastics the convergent heat-set hole is about 4.0 mm at M3, 5.6 mm at M4, 6.4 mm at M5 and 8.0 mm at M6, with the hole depth set to the insert length plus two thread pitches and the boss outer diameter 2–3× the insert diameter. Open the hole about 0.08 mm for 15%+ filler and 0.15 mm for 35%+ filler. See the boss-hole data and design-rules tables above, and always validate on your own moulding.
As indicative ranges for correctly installed heat-set inserts in representative engineering thermoplastics: roughly 350–2,900 N pull-out and 0.5–5 Nm torque-out at M3, rising to about 1,700–9,200 N and 7–26 Nm at M6. Performance is strongly host-dependent — validate on your own boss, resin and process. Note that glass fill does not reliably raise pull-out; it mainly raises torque-out, stiffness and creep resistance.
Set the tip to the host resin’s softening temperature plus an offset — about +28 °C for unfilled grades and +83 °C for filled grades — not to a fixed insert setpoint. The aim is to soften the boss so plastic flows into the knurls, not to melt it. See the per-resin table above and the full installation guide.