⚡ Key Takeaways
- What they do: create a high-strength internal thread in a soft light-alloy parent (aluminium, magnesium, cast iron).
- Four types: plain through-hole, plain blind-hole, locking through-hole and locking blind-hole.
- Standards: GB/T 24425.1 (plain, through), .2 (plain, blind), .3 (locking, through), .4 (locking, blind).
- Material: cold-rolled diamond-section stainless 304 wire, with Inconel available for high temperature.
- Strength: after installation the thread reaches class 8–12 and can be assembled repeatedly.
📑 Contents
1. What a wire thread insert solves
2. Choosing between the four types
3. Installation
4. Selection FAQ
1. What a wire thread insert solves
2. Choosing between the four types
3. Installation
4. Selection FAQ
1. What a wire thread insert solves
Tapping a soft material directly — ADC12 die casting, AZ91D magnesium, cast iron — means:
- The thread strips after 3–5 assemblies;
- Strength is low and load capacity is poor;
- Repairing a stripped hole means drilling it oversize.
With a stainless wire insert installed:
- The internal thread becomes stainless steel, at class 8–12 strength;
- It can be assembled and disassembled repeatedly;
- A stripped hole can be repaired without a large oversize.
2. Choosing between the four types
| Type | Standard | Characteristics | Application |
|---|---|---|---|
| Plain, through-hole | GB/T 24425.1 | Open both ends; the driving tang is broken off after installation | General connections |
| Plain, blind-hole | GB/T 24425.2 | No tang to break off, suited to blind holes | Blind holes, deep holes |
| Locking, through-hole | GB/T 24425.3 | Has a polygonal locking coil that resists loosening | Vibration environments |
| Locking, blind-hole | GB/T 24425.4 | No tang plus a locking coil | Blind holes with vibration |
3. Installation
- Drill the tapping hole with the dedicated drill (1.5–3 mm larger than nominal);
- Cut the special insert thread with the dedicated tap — not an ordinary thread tap;
- Screw the insert in with the installation tool, then break off the driving tang;
- Clear the chips and run in a standard bolt.
Important: a wire insert uses a special thread. The tapping hole for M6 is around 8–9 mm, not the 5 mm of an ordinary M6 tap.
4. Selection FAQ
Q: What do I use for M6 in an aluminium housing? A plain through-hole insert, 1D length, is enough.
Q: Does a vibrating joint need the locking type? Yes — the locking coil works like the nylon patch on a lock nut.
Q: Why can't the tang be broken off in a blind hole? The broken tang would fall to the bottom of the hole.
🛠️ Engineering support: Toprecision supplies the full M3–M24 wire thread insert range, including installation tooling.
👉 Engineering services ｜ 👉 Request a technical quote
👉 Engineering services ｜ 👉 Request a technical quote