Helical inserts for thread repair–Pros and Cons

For stripped sockets, we have helical inserts for thread repair, which uses a commonly adopted threaded insert technology but is tailored for engine and mechanical parts repair. Specifically, helical inserts are used to replace stripped or worn-out threads. It uses a coiled wire that when inserted into the threaded hole, provides new threads for the bolt or screw to be reinserted.

Threaded inserts as technology are broadly used, and there are many options to look at for thread repair. Later, we also discuss the limits of thread inserts and what innovations present new ways to repair threads.

Threaded Insert systems

Helical inserts are part of what is referred to as ‘threaded insert’ technology. 

Threaded inserts are commonly used as well in ready-to-assemble furniture or kit furniture. The use of threaded inserts allows for quick assembly and disassembly. It is also used in strengthening composite materials, or structures that are ‘sandwiched’ panels that use a thick but light core, similar to the ones used in claddings, signages, and ceilings. 

On the other hand, helical inserts are specially made for mechanical parts. It is a coiled wire that is cross-sectionally designed to be diamond-like. This would allow the insert to screw into the tapped threads and provide new threads for the bolts to move and screw into. 

It is also generally called Screw Thread Insert (STI), but this is a term that is uncommon. The most famous brand is Helicoil, but there are other products in the market as well.

Overall, such insert systems allow for a structure to spread its weight equally into an area, and allow tension and load to be distributed. Thus, the insert systems prolong the structure’s working lifespan.

Helical Inserts

In order to complete the process of screwing a threaded insert, you have to go through several steps which we outlined here, too. 

1. Look for the correct threaded insert size for the bolt and socket
2. Use the drill bit to adjust the size of the hole and enlarge the hole for the threaded insert
3. Tap into the hole and base metal using the corresponding tap size
4. Insert the thread insert using the wrench and installation tool
5. Remove the tang

Though these steps seem straightforward, it takes some key skills to accomplish these steps. You would need the following skills and resources:

1. Ensure to tap correctly with a perpendicular angle
2. Have the right size of tap and Helicoil available. 
3. Ability to use a die (if the bolt is stripped, threaded, or cross-threaded, too)

As a rule of thumb, the size of the helical insert is the size of the diameter of the screw. This would require you to make the right measurement. Furthermore, you can’t risk using a poor or old tap. The safest way is to buy an entire kit, which would include the following items:

1. Threaded insert
2. STI Tap
3. Drill bit 
4. Installation tool
5. Tool to remove tang

Helical Insert Products

Helicoil – Helicoils are the most famous product in the helical insert market. Just search on the internet for ‘Helicoil’, and you have a variety of options to choose from. There are also OEM versions but are not recommended. 

Helicoils have been in the market for decades already. It was originally invented by the company Ekhart Technologies, which merged with Black + Decker in 1989. 

Although this piece of historical tidbit seems trivial, it’s good to understand why Helicoil has been a force in the market. It has a tradition of durability and innovation that extends decades ago. 

The next time you plan to buy a Helicoil, though, keep in mind that there are other options, too. Meanwhile, there are plenty of innovations in the market as well, when it comes to repairing threads.

E-Z Lok. E-Z Lok is the version of Helicoil which came afterward. It’s basically the same as Helicoil but offers some additional benefits. 

• Can resist temperatures up to 800 degrees Fahrenheit
• Gives protection from stripping and wearing down
• Has specific insert tailored for spark plugs

Timesert Solid inserts. Solid inserts are like Helicoils but offer more stability. Its flange on the top prevents it from pushing down into the base metal. It also has a locking mechanism at the bottom, where the internal threads are cold rolled to ensure that the external threads expand into the base metal. The self-locking action plus the flange on top offer more security for the joint. 

Helical insert products have been in the market for a long time. Despite the high reliability, its intrinsic limitation is that there are only as many sizes as there are bolt diameters. There is not enough flexibility to meet the demands of quick fixes, field equipment maintenance, and various industrial applications. 

Rotary Alternative

For Rotary thread, the cost of investing in almost the same price point shows parity of effort but a greater return on investment. Compared to investing in helical inserts, which would have a one-time use, Rotary threads can be used several times on different threads–whether inner, outer, metric, inch or pipe. 

In fact, Rotary threads have been tested on external threads as large as cranes, and as small as engine bolts. 

Rotary thread offers the same tradition of excellence as well. Having come from a family of machinists and engineers, the innovators behind the award-winning product have been in the business for more than five decades.

The pros of using Rotary thread boil down to:

• Versatility (works with internal and external threads)
• Return on investment
• Cost

Conclusion

helical inserts are a great way to build on assembly parts that can benefit from additional strength. Threaded inserts also help alleviate the burden from the load, and into the bolt. 

However, versatility as a factor comes as a factor for Rotary thread. For us, helical inserts for thread repair are a good option for sockets that are in need of constant assembly and disassembly.