Thread repair - Quick and easy

When fasteners are removed improperly or forcibly, the threads can easily be damaged. In this case, there are two options: replace the component or repair the thread. Which option is best must be decided on a case-by-case basis. However, most parts can be restored through a thread repair and will subsequently hold just as securely and firmly as before.

When repairing threads, it is essential to use reliable tools and high-quality accessories to reestablish a durable connection. In this article, we will explain the methods available for thread repair and the best approaches to each. Of course, you can find the appropriate tools for thread repair in our BAER Tools store.

Damaged Thread – How can a thread be damaged?

Several causes can lead to a damaged thread. The most common reasons include:

• Over-tightening of the screw.
• Incorrect alignment of the bolt.
• Thread corrosion.

In some cases, lubricating the screw with a so-called penetrating oil can reduce friction, making it easier to remove the screw. However, this method can be time-consuming and isn't always successful. Also, using pliers instead of a screwdriver doesn't always work and is generally only possible with pan-head screws. As you can see, we're not fans of this method.

For screws that are stuck due to rust, experimenting with rust remover is possible. However, this method is also time-consuming and impractical in an industrial setting. In such scenarios, swift and effective action is required. Using a repair thread and a high-quality thread repair insert can help achieve a stable and resilient solution quickly.

Repairing external and internal threads

When repairing internal threads, durable and corrosion-resistant elements are used, often referred to as thread armor or thread inserts. Both defective and torn-out threads can be conveniently restored using wire thread inserts. This method works for plastics and metals alike. The BaerFix thread inserts, as well as the necessary drills or tools like die stocks or die holders, are available in our store in the best quality!

Two types of thread repairs are possible:

• Repairing external threads (e.g., screws or bolts): In this case, the repair can be done by re-cutting the thread using a thread cutting die.
• Repairing internal threads (e.g., nuts): Two solutions are possible: repairing with a wire thread insert (by BaerCoil) or a self-tapping thread insert (by BaerFix).

Should you repair threads with wire thread inserts or self-tapping inserts?

Since an external thread can simply be re-cut using a thread cutting die, we'll explain the differences and processes of repair methods for the internal thread.

Important in choosing the right method for thread repair is the examination of how much base material remains. This matters because the thread inserts of the self-tapping inserts are much thicker (i.e., they have a larger external diameter) than the wire thread inserts. We'll explain both types of thread inserts in more detail below:

Self-tapping thread inserts cut into the existing material, removing some of it in the process. Ideally, they are used only for materials with tensile strength up to 450 N/mm². For harder materials, the host thread should be pre-cut with a taper tap to ensure the insert doesn't remove more material while being inserted.

2. Wire thread insert for thread repair:

Metal threads with low shear strength can easily be repaired with a wire thread insert – the thread remains unchanged in comparison to the self-tapping insert. Therefore, repairing threads using a wire thread insert from BaerCoil is possible even with limited space. These require less base material, allowing for shorter fastening solutions, saving valuable resources. Additionally, the repaired thread achieves improved surface quality and high corrosion resistance due to the stainless-steel insert.

Repairing damaged threads using wire thread inserts and self-tapping inserts

Repairing threads using both methods is quick and straightforward. Additionally, we're always here to provide guidance if you encounter any issues. We've also created informative videos to assist you, which can easily be accessed on YouTube. You can find the links to these videos below.

Repairing threads with wire thread inserts:

• Start by removing the old thread and subsequently drill it out to a slightly larger size.
• Using an EG-tap or STI-tap, cut the host thread for the thread insert.
• With the appropriate insertion tool, simply screw in the thread insert.
• For thread inserts with a driving tang, make sure to use it first and then break it off after installation.

In our store, you'll find both wire thread inserts and thread taps, insertion tools, and tang break-off tools.

Repairing threads with self-tapping threaded insertss:

This method is even faster than the one with wire thread inserts, however, as mentioned above, it is only feasible if there is enough material with a tensile strength of 450 N/mm² or less.

When repairing threads, you proceed as follows:

• You drill a larger core hole.
• Then place the threaded insert on the appropriate inserting tool and lock it with the lock nut (here you have the choice between a hand inserting tool or a machine inserting tool).
• NunNow screw the thread insert into the hole.
• Now loosen the lock nuts and finally unscrew the insertion tool. Done!