Tanged and Tangless® inserts are both types of wire thread inserts used for strengthening and repairing threaded holes in materials such as metal, plastic, or composite. They provide a durable and reliable means for creating strong threads in materials that may be prone to stripping or wear.
The primary difference between both insert types are the use of a tang (tanged) or a notch (Tangless) to install it. Both insert types have advantages and disadvantages as we will explore in this article.
The reason behind the Tangless concept is simple: in safety critical applications such as Aerospace and Automotive engines the Tang is considered a Foreign Object Debris (FOD) risk. If the broken tang falls into the casting / component it can cause serious issues, leading to manufacturers counting the tangs post-installation out of necessity. This introduces an extra step into the process which adds costs and time.
There are other benefits to Tangless inserts which we will explore shortly, but Tanged inserts retain some advantages over its newer counterpart.
Tanged Inserts – vs Tangless
- Lower cost of component – both tooling & inserts are simpler to manufacture and therefore cheaper.
- Installation reliability – the tang is tough and enables the user to apply more force to install the insert. In some cases this can compensate for imperfect hole preparation and cleanliness.
- Superior range of sizes and thread forms – the nature of tanged inserts means they can scale very well in production. Unlike Tangless inserts (which are manufactured up to M16) tanged inserts are available in a complete range of unified and metric sizes, locking and non-locking, bulk and strip-feed.
- In spite of concerns with tang removal, tanged inserts have been around for a long time and meet or exceed all applicable military, aerospace, and commercial standards.
- Tanged inserts are often specified on drawings. Whilst not a distinct advantage it means a new testing and approval process may be required to qualify Tangless inserts.
- The tang poses a risk in certain applications
- The tang removal process is an additional step which costs time and money
Tangless Inserts – vs Tanged
- With no tang to remove manufacturers can eliminate the Foreign Object Debris (FOD) risk.
- Tangless inserts can offer process cost savings by significantly decreasing installation and inspection time. Eliminating the tang break means one less installation step and eliminates the need to count tangs (for high volume applications this saving can be considerable).
- A Tangless insert has a Bi-Directional design which can be installed from either end eliminating the need for orientation: this saves time in installation and improves ergonomics for the user. It is also ideal for automated applications where insert orientation requires specialist equipment.
- The quick, non-destructive insert removal process prevents damage to machined aluminium parts or castings should insert removal be required.
- Tangless inserts are approved for use on many Aerospace and military programs under NASM8846, NAS1130 NA0276 and MA1565.
- Higher cost: Tangless inserts are generally more expensive than tanged inserts due to their design and manufacturing complexity. Tangless installation tooling is also specialised and costs more than equivalents for tanged inserts.
- The notch installation method can be sensitive to swarf, dirt and poorly prepared holes.
- Tangless inserts are only available in a limited range of sizes (From M2 to M16 or equivalent).
Your manufacturing processes / requirements / conditions will determine which type of wire thread insert is right for your application. This should be assessed on an application-by-application basis.
Standard wire thread inserts are still the best option for many insert applications such as Automotive, machinery, power generation and general thread repair.
For applications where 1) FOD is a concern, 2) high-volume of inserts will be installed, 3) automated is required, Tangless inserts can provide the perfect solution. Typical markets for Tangless include Aerospace, Engine applications in Automotive, industrial and consumer electronics and medical equipment.
Recoil manufacturers a complete range of tanged inserts, tangless inserts and installation tooling. Contact us for support with your application.