Over time, threads in industrial applications can wear out or become stripped, requiring repair. Thread repair inserts and kits allow users to restore worn threads by creating strong, durable replacements that match the original size and shape. This method is significantly more cost-effective than replacing the entire component. This guide covers the various types of coil inserts, the tools needed for repair, and the materials used in thread inserts.
Thread Repair Technical Information: Styles, Types, and Easy Steps to Repair
Thread repair inserts offer a quick and permanent solution for restoring stripped or damaged tapped holes caused by wear, corrosion, or over-tightening.
4 Easy Steps for Coil Type Inserts
1
Drill
Drill a hole within the application.
2
Tap
Tap the hole to a depth that matches the length of the insert and the bolt to be used.
3
Install
Select the correct insert length and use the installation tool to wind it into the hole until the top coil sits ¼ to ½ inch below the surface.
4
Tang Removal
Use a break-off rod or a punch of the appropriate size to remove the tang from inside the insert.
Coil Type Inserts
Repairs stripped or damaged tapped holes caused by wear, corrosion, or over-torque.
Coil tension secures the insert without stressing the surrounding material.
Resistant to vibration and impact.
Heli-Coil
Built-in locking mechanism grips the bolt to prevent loosening from vibration or impact.
Removes the need for additional thread-locking compounds.
Supports repeated assembly and disassembly with minimal loss of locking torque.
Tanged
Tangs must be removed to prevent interference with the assembled bolt.
Removal is quick, automatic, and can be done one-handed.
Requires a tang break-off tool.
Tangless
No tang break-off tool required.
Installs quickly and easily from either end.
Strip Feed Reels
Bulk inserts on plastic strips are available in reels of 500 or 1,000.
Minimizes handling to boost installation speed.
Designed for use with power installation tools in high-volume production.
Surface Treatments for Coil Type Inserts
Primer Free II®
Chromate-free and RoHS compliant.
Eliminates the need for zinc primer.
Prevents galvanic corrosion between the insert and the parent material.
Resolves locking torque issues related to primers.
Enhances installation productivity.
Provides added lubrication for easier insert installation.
Gall Resistant
Made from Nitronic 60™.
No additional coating or plating required.
Non-magnetic and particle-free.
Suitable for vacuum environment applications.
Dry Film Lubricant
Adds lubrication for high-friction applications.
Withstands temperatures up to 400°F.
Offers corrosion-resistant properties.
Thread Repair Kits
Fast and convenient solution for repairing stripped or damaged tapped holes.
Most kits include: drill, tap, installation tool, tang break-off tool, and a supply of inserts (unless otherwise specified).
Available in Inch, Metric, Spark Plug, and Pipe Thread series.
Tools
Hand Installation
- Used for installing inserts into tapped holes.
- Tool selection depends on the insert’s thread size:
- - Use a Mandrel for coarse threads.
- - Use a Prewinder for fine threads.
Hand Extraction
- Used to remove inserts from tapped holes.
- Insert the tool into the hole and align it with the insert.
- Strike the tool head lightly, then turn counterclockwise while applying steady downward pressure.
Tang Break-Off
- Removes the tang after installation to prevent interference with the assembled bolt.
- Compatible with insert sizes up to 1/2" and M12 nominal diameter.
Power
- Designed for high-volume production.
- It can be used as a handheld tool or mounted to a workstation.
- Includes an air motor, adapter, and front-end assembly.
- Supports insert sizes up to 1/2" and M12 nominal diameter.
- Front-end assembly includes:
- - Prewinder
- - Mandrel
- - Spacers
Screw Thread Insert (STI) Taps
- Used for tapping holes to meet standard screw thread specifications.
Materials
Carbon Steel
Standard, all-purpose material suitable for general applications.
Stainless Steel
Corrosion-resistant for long-lasting performance.
Ideal for OEM, repair, and overhaul applications.
Titanium
High strength-to-weight ratio for enhanced performance.
Corrosion-resistant for durability in harsh environments.
Excellent stability under low-pressure conditions.
Nitronic 60™
Compatible with stainless steel screws.
Ideal for use in vacuum environments.
Particle-free, non-magnetic, and highly resistant to galling.
Non-Coil Type Inserts
Solid
Designed to fill oversized or misaligned holes that were drilled or tapped incorrectly.
Self-Locking
Repairs stripped or worn threads in jigs, fixtures, bolster plates, dies, and machine tools.
Integrated locking element keeps the insert securely in place, even under vibration.
Keylocking
Equipped with 2 or 4 locking keys for superior holding power across various materials.
Inserts with internal threads M7 or larger include four locking keys; smaller sizes come with two locking keys.
Solid Thread Insert Styles
Thin Wall – Ideal for applications where wall thickness or weight is not an area of critical concern.
Heavy-Duty – Most commonly used insert, available in both coarse and fine thread options.
Extra Heavy-Duty - The insert is engineered with increased wall thickness and a larger external thread area, delivering superior pull-out strength and holding power. In high shear strength materials, it offers performance comparable to standard heavy-duty inserts, while in low shear strength materials, it ensures maximum holding power and resistance to pull-out.