How To Skillfully Remove Broken Compression Screws And Bolts?

In the assembly of precision sheet metal parts, electronic equipment housings, and mechanical components, fasteners such as self-clinching screws, self-clinching studs, and self-clinching bolts are widely used. These self-clinching threaded fasteners securely embed the threaded element into the metal sheet through caulking, creating a high-strength connection. However, during use or maintenance, these fasteners can sometimes break due to stress concentration, material fatigue, excessive torque, or corrosion. Efficiently and safely removing broken compression screws or bolts is a common and critical technical challenge in manufacturing and repair.

The following describes several commonly used engineering methods applicable to various types of clinching screws, **push-in clinching screws**, and self-clinching compression screws.
 

This method is suitable for screws or bolts with relatively flat fractures and not severely seized.

The steps are as follows:

Surface Cleaning: First, remove oil and rust from the fractured surface of the self-clinching screw, ensuring a clean work area.

Centering: Use a center punch to create a pilot hole in the center of the fracture surface to avoid deviation.

Drilling Guide: Use an electric drill equipped with a 6–8 mm diameter drill bit to drill a hole at the center punch. Once the hole is drilled through, replace it with a drill bit approximately 16 mm in diameter to enlarge the hole.

Precautions: Maintain a vertical position throughout the drilling process to avoid damaging the parent material's thread structure.

The center hole created by drilling provides structural clearance for subsequent overlay welding or extraction operations and also helps to break up stress bonds between the threads.
 

For self-clinching bolts and self-clinching screws that have become firmly embedded or rusted, overlay welding can be used to loosen them and restore them to a workable shape.

The steps are as follows:

Overlay Welding Preparation: Use a welding rod with a diameter of 3.2 mm or less and apply overlay welding from the inside outwards to the drilled hole in the broken bolt. The overlay welding depth should generally be limited to half the original bolt length to prevent burning through the wall thickness.

Welding to a Column: After overlay welding to the top of the bolt, continue overlaying to form a cylinder with a diameter of 14–16 mm and a height of approximately 8–10 mm. This will provide a bearing point for subsequent extraction.

Heat Shock Loosening: After welding, gently tap the stud with a hammer to create vibration between the threads. The thermal expansion and contraction caused by heating and cooling during welding can help loosen the broken bolt.

Welding Studs: If rust seeps from the fracture, weld a standoff or self-clinching stud of appropriate size onto the overlay stud.

Twisting Out Broken Parts: After welding, when the part is slightly cool, use a wrench and gently tap it left and right to easily remove the broken clinching screw or bolt.

Finally, clean the original threaded hole with a tap to remove any remaining rust and impurities, ensuring smooth and reliable subsequent assembly.

Thermal Expansion and Contraction Principle: The high temperature generated during overlay welding causes the metal to expand locally, creating a slight gap upon cooling, which reduces thread engagement.

Vibration Loosening Effect: Hammering a broken bolt to vibrate axially can further disrupt the bond.

Thread Protection: Avoid damaging the base material threads during operation; otherwise, re-tapping or replacing a larger self-clinching threaded fastener will be necessary.

Preventing Re-Breakage: When installing new parts, control the torque value to ensure a good engagement between the push-in clinching screw and the sheet metal without overloading.

In modern mechanical manufacturing and sheet metal assembly, fasteners such as self-clinching screws, self-clinching studs, and self-clinching bolts are widely used due to their high strength, stability, and assembly efficiency. However, the removal of broken parts remains a significant challenge in on-site maintenance. By effectively utilizing drilling and overlay welding methods, broken parts can be removed safely and efficiently while also maximizing the preservation of the parent material structure and thread accuracy.

For structural components using Self-Clinching Screws or other high-performance Self-Clinching Compression Screws, regular maintenance, torque control, and anti-corrosion treatment are key to extending their service life. In the future, with the continued optimization of the materials and structures of clinching screws and self-clinching threaded fasteners, this type of fastening technology will play an even greater role in precision electronics, automotive manufacturing, aviation, and new energy equipment.