Thread Metric Inserts & Repair Kits

Thread metric inserts (helicoils, screw-in thread sleeves) restore damaged or worn metric threads in metal or hard plastics; use a repair kit when threads are stripped, cross-threaded, or when you need a stronger threaded connection in softer materials

Match the insert size to the original metric thread (e.g., M6, M8), verify required insert length and outer diameter for hole fit, and pick a type (coiled wire/helical vs. solid threaded sleeves) based on load, vibration resistance, and material compatibility

Typical kits include a drill bit for oversize hole, a specific tap to cut the new thread, an insertion tool or tang-break tool, and sometimes a thread-locking adhesive; always follow the kit's drill and tap size chart for the insert size

Coiled wire inserts provide a permanent internal thread but the insert itself can sometimes be removed and replaced; solid screw-in sleeves are generally permanent once installed and often require extraction tools for removal

Choose stainless steel or coated inserts (zinc, nickel, or phosphate coatings) for corrosion resistance; consider hardened steel or grade-specified materials when higher shear strength or wear resistance is needed

Kits span a wide range depending on insert types and included tools; common consumer kits are often under $50, while professional multi-size sets with taps and drivers can cost more

Avoid using wrong drill or tap sizes, failing to clean chips from the hole, not seating the insert fully, and over-torquing fasteners; these errors can reduce holding strength or damage the parent material