Plastic threaded inserts diminish fighter jet’s radar signature

When Fitsco developed a new range of plastic threaded inserts in 2017, the company had no idea that one of the early applications to be found could see it being specified for use at 50,000 feet and Mach 2+ on a front-line fighter aircraft. But that is exactly what has happened with the new LiteFit plastic threaded insert after it was specified as a ‘metal replacement’ part for an ‘in-cockpit’ application on the Eurofighter Typhoon.

LiteFit plastic inserts take off with the Eurofighter Typhoon.
Fitsco’s new LiteFit plastic inserts are claimed to provide a weight saving of up to 80% over ordinary metal inserts.

In order to achieve reduced overall platform conductivity and also to deliver a diminished radar signature, many modern military aerospace designs have been moving away from metallic parts where possible and LiteFit helped achieve this on the Eurofighter application.

The LiteFit range of plastic inserts was conceived and developed entirely in-house by the Fitsco R&D team at the company’s headquarters in Shropshire and is claimed to deliver a substantial step forward in insert design. “It opens up interesting new possibilities for design and production engineering teams in many market sectors by bringing a number of key advantages over standard metal inserts” said Fitsco Founder & CEO, Philip Schofield.

Traditional metal inserts made of brass, steel and stainless are still used extensively in the joining of plastics. Despite the obvious weight penalty that comes with brass, steel and stainless, this aspect is often deemed immaterial or irrelevant for a variety of general industrial applications. However, design engineers seeking to reduce overall weight in applications where it does matter have so far been stymied when seeking a mechanical process to either join plastics and composites together or attach other items to them using threaded inserts.

As a result, it remains common to see 21st Century materials being joined using threaded insert technologies and processes that emanate from the 1950s - and with a commensurate weight penalty.  

However, with the introduction of LiteFit, Fitsco points out that compared to brass, steel or stainless steel threaded inserts, their new plastic product delivers an individual-item weight saving of up to 80%.

Concurrent with the Eurofighter Typhoon application in the UK another early enquiry has highlighted the weight-saving properties of LiteFit inserts. It came from an automotive manufacturer in the United States of America, where LiteFit plastic inserts are under active consideration for an application which will allow the manufacturer to convert from a metal fabricated part to a significantly lighter – and potentially more durable - plastic version instead.

 ‘Standard’ molding operations usually involve the molding of a blind hole followed by the installation of metal inserts. However, by installing the new LiteFit threaded inserts into the mold tool itself, a technical benefit can be gained by achieving better material-flow integrity around the area of the insert itself. “This increase in integrity has the potential to make a big difference in some cases” says Schofield.

In addition to this design engineering advantage, he also points out that one of the other advantages delivered by LiteFit is the reduction of overall assembly costs. By having LiteFit installed as part of the mold itself, OEMs can do away with the need for the additional installation equipment, time and labor needed to install metal threaded inserts after the molded part has been made. On some projects this element alone can cost more than the original molding did itself.

The advantages ‘per project’ can be readily calculated by production personnel and this aspect was also an additional key driver on the American automotive application previously mentioned.

LiteFit plastic inserts can also be color matched to blend with the ‘parent’ material into which the inserts are being installed. The company believes that for many manufacturers this could provide a quality of finish and visual appeal that has not thus far been obtainable using ‘ordinary’ metal threaded inserts.

Further, as Schofield concluded “Our new range of LiteFit inserts are fully recyclable, food industry compliant, have excellent chemical and corrosion resistance and don’t require plating. They offer good mechanical strength and are also great electrical insulators too. We are working on some interesting applications in the medical market as well as others in automotive and aerospace.”

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