Invisible but essential

AMJun19Features - bollhoff1
AMJun19Features - bollhoff1

Still innovating on existing technology that has been in use for over 65 years, Böllhoff’s tried and tested Helicoil metallic thread insert shows why it’s essential to search for a better answer to the needs of an ever-evolving sector.

 

Fastener and assembly systems specialists, Böllhoff (hall 2B, stand E188) will showcase three of its complementary systems during this year’s Paris Airshow: its brand-new Helicoil PrimerFree 2 which was launched at the beginning of 2019, its ONSERT, a fastener for all kinds of materials and all kinds of applications, and its HITSERT Screwlock, a special combination of two fasteners made for thermoplastics.

According to Böllhoff, screw joints are the invisible, but essential part of any aircraft or even spacecraft. However, some of them still need particular caution when submitted to severe conditions such as extreme vibration, high temperature, pressure, humidity, corrosion, alternating loads, and so on. Assembly systems in the aerospace sector must meet these specifications and had better not come loose whilst flying.

This is why, 65 years ago Böllhoff invented the helicoil: a metallic thread insert that reinforces assemblies, especially with low-strength materials such as aluminium, aluminium-magnesium alloys and fibre-reinforced plastics.

Helicoil thread inserts are tried and tested and have become a widely used structural component, creating high strength, heat and wear-resistant threads. With a helicoil, forces are transferred from flank to flank into the pilot thread.

The very first innovations on Böllhoff’s Helicoil product were to create a Tang-free version and a Screwlock version as well. The Tang-free product provides a time and cost-saving solution, as there is no need to break off and remove the tang anymore.

A Screwlock version was made to avoid any involuntary unscrewing and to limit the impact of vibration on the assembly. As a result, the thread insert became a useful component to strengthen and secure assemblies in the aerospace sector, whereas the free-running version allows the screw to be removed, e.g. for maintenance, or for replacement.

But there was a need that had never been fulfilled before: having a thread insert capable itself - without any additional primer or coating - to isolate from electrical current and galvanic corrosion. In 2019, this need has found its innovation with Böllhoff’s Helicoil Primer-Free 2.

Helicoil Primer-Free 2 completely protects magnesium or aluminium components against galvanic corrosion

Helicoil Primer-Free 2 completely protects magnesium or aluminium components against galvanic corrosion. Compared to other coated thread inserts, it has a resin-bonded, Teflon-impregnated fluoropolymer coating that ensures an even, electrically-insulating coating and therefore overall protection against galvanic cell formation.

Primer-Free 2 replaces previous zinc-chromate primers, which had to be assembled in the holding thread before the Helicoil installation. Furthermore, Helicoil insert with Primer-Free 2 can be mounted into the standard Helicoil threads with the corresponding standard installation tool and into holding materials, such as aluminium and magnesium.

This innovation has several advantages and complies with standards NAS1130 and NA0276 and the prevailing torques are defined in technical delivery conditions NASM8846 and MA1565. Not only does it save time, but this RoHS-compliant and chromium (VI)-free fastener also saves money - thanks to its efficient installation and guarantees a strong and reliable assembly.

Being able to innovate on existing technology that has been used for more than 65 years by all the manufacturers of the aerospace and aeronautics industry shows how essential and indispensable it is to always search for a better answer to the needs and constraints of a continuously evolving sector.

www.boellhoff.com

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Bollhoff

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