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Threaded Inserts

Threaded Inserts

Helical coil, key-locking, heat-set and press-in inserts.

Also searched as: helicoilheat set insertskeensertsbrass insertsthread repair

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About threaded inserts

Threaded inserts are fasteners that create a durable, reusable threaded hole in a material, often to repair damaged threads or to provide stronger threads in softer materials. They are broadly categorized by their installation method and locking mechanism. Helical coil inserts, commonly known as wire thread inserts, are precision-formed coils of diamond-shaped stainless steel wire that provide strong, corrosion-resistant internal threads. Key-locking inserts, or Keenserts, feature keys that are driven down into the parent material to positively lock the insert in place, offering high resistance to rotation and pull-out. Heat-set inserts are designed for thermoplastic materials, installed by heating the insert and pressing it into a pre-drilled or molded hole, allowing the plastic to flow into knurls and undercuts for retention. Press-in inserts are cold-pressed into a hole, relying on interference fit, knurling, or barbs for retention. Selection criteria include the nominal thread size (e.g., M6x1.0, 1/4-20 UNC), thread series (coarse or fine), length, and the parent material. Common materials for inserts include stainless steel (303, 304, 316), brass, and hardened steel, often with finishes like zinc plating or passivation for corrosion resistance.

How to choose

Selecting a threaded insert requires a sequential decision process. First, determine the required internal thread size and pitch (e.g., M8x1.25, 1/2-13 UNC). Second, identify the parent material into which the insert will be installed (e.g., aluminum, plastic, wood, steel) as this dictates the insert type (helical coil for metal, heat-set for thermoplastics). Third, specify the required pull-out and torque-out strength; key-locking inserts offer superior performance here. Fourth, consider the installation method and available tooling (manual, automated, heat-staking). Finally, select the insert material and any necessary plating or coating based on environmental conditions and galvanic compatibility requirements.