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Common Questions about Threaded Inserts
What is a threaded insert?
A threaded insert is a metal sleeve installed into a host material to provide a strong, durable thread. Inserts are used where the host material is too soft for direct threading — timber, plastic, aluminium — or where threads will see repeated assembly and disassembly. Common types include wire-thread, self-tapping and press-fit inserts.
What is the difference between a Helicoil and a self-tapping insert?
Helicoil-style or wire thread inserts are coiled stainless wire that screws into a tapped hole, providing a hardened internal thread. Self-tapping inserts have external cutting threads and screw directly into a drilled hole — they cut their own thread in soft materials like timber, plastic and soft alloy without pre-tapping.
Why would I use a threaded insert?
Common reasons include repairing stripped threads in aluminium engine blocks, gearbox housings or machine castings; strengthening threads in soft materials such as timber, plastic and soft alloy; creating reusable threads in housings that see repeated assembly; making threads in materials too soft to hold load reliably without an insert.
Are threaded inserts permanent?
Wire thread inserts are designed to be permanent — once installed they grip the host thread tightly and do not back out under normal load. Self-tapping inserts are permanent in soft materials. Specialised inserts with retention features, such as Keenserts, use locking keys for high-vibration permanent installs in critical applications and structural joints.
What materials are threaded inserts available in?
Stainless steel is the workshop standard for wire thread inserts — strong, corrosion-resistant and suiting most applications. Brass and aluminium self-tapping inserts serve electrical, decorative and lightweight assembly work. AIMS stocks Recoil and other branded threaded inserts across metric and imperial sizes for workshop, automotive and industrial use.
Threaded Insert Selection — Quick Reference
Threaded inserts repair stripped/damaged threads, reinforce threads in soft materials (Al/plastic), and create durable threads for repeated assembly. Selection turns on substrate (Al/steel/plastic), load (light/heavy), and whether removability matters.
| Insert Type | Best For | Brand |
|---|---|---|
| Wire Thread Insert — Tang | General-purpose thread repair in aluminium + soft metals | Recoil (workshop standard) |
| Wire Thread Insert — Tangless | Aerospace + critical engineering — no tang break-off contamination | Recoil tangless |
| Key-Locking Insert | HEAVY-load applications — solid bushing locked by keys driven into base material | EZ Lok, KLI |
| Threaded Bushing (Solid) | Repeated assembly + disassembly — bolts won't strip the insert | Time-Sert, KLI |
| Self-Tapping Insert | Soft material (plastics, soft Al) — cuts its own thread on install | EZ Lok |
| Press-In Insert (Knurled) | Thermoplastics — pressed/heat-staked into moulded hole | Tappex, EZ Lok |
| Helical Coil Insert | Same as wire insert — alternative branding | Helicoil (legacy) |
| Time-Sert (Solid Bushing) | HEAD BOLT + CRITICAL LOAD repairs — strongest single-use solid insert | Time-Sert |
Critical: Match insert thread (internal) to bolt + drill/tap (external) to substrate. Recoil + Time-Sert kits include matched drill + tap + installation tool for each size. Wire inserts give thread strength in aluminium often stronger than steel original (load distribution along the helix). For thread extraction first, see extraction tools. Brands: Recoil, EZ Lok, KLI. Companion: threading, taps, cobalt drill bits.
Threaded Inserts for Thread Repair and Reinforcement
Threaded inserts repair stripped, damaged, or worn threaded holes, create strong threaded connections in soft materials such as aluminium and plastics, and reinforce threads in components subject to repeated assembly and heavy loading. The insert is installed into a prepared oversize hole where it creates a new correctly sized internal thread that is typically stronger than the original base material thread. AIMS stocks threaded inserts in a comprehensive range of metric and imperial sizes across the major insert types for engineering, maintenance, and production applications across Australian industry.
Wire Thread Inserts — Recoil
Wire thread inserts — supplied under the Recoil brand — are coil-wound stainless steel inserts that provide a new internal thread when installed in a tapped oversize hole. They are the most widely used thread repair method in engineering workshops due to their comprehensive size range, the strength of the repaired thread in aluminium and other soft metals, and the availability of installation kits containing drill, tap, and insertion tool for each size. Tang-drive inserts require a tang break-off tool after installation. Tangless inserts — the preferred type in aerospace and critical engineering applications — eliminate this step and remove the risk of broken tang fragments contaminating sealed bores or precision components.
Key-Locking Inserts
Key-locking inserts are solid steel or stainless steel inserts with external coarse threads and internal machine thread, locked in place by keys driven into slots on the insert body after installation. They provide higher pull-out resistance than wire thread inserts and are preferred in applications subject to heavy axial loads, vibration that could unscrew a threaded-in insert, or where permanent locking against rotation is required. Key-locking inserts are widely used in aerospace, heavy engineering, and defence equipment applications where the integrity of the threaded joint is critical to structural safety.
Press-In and Moulded Inserts for Plastics
Press-in inserts for plastics and soft metals use knurled or serrated external features to grip the host material when pressed or driven into a pre-drilled hole. Heat-set inserts for thermoplastics use a soldering iron or heat installation tool to soften the surrounding plastic during insertion, producing a strong flush installation as the material cools and solidifies around the insert's external features. These are widely used in injection-moulded housings, enclosures, and structural plastic assemblies where standard tapped threads in the base plastic would strip under normal fastener clamping forces.
For insert sizing, thread repair solutions, or installation kit supply, contact our team.