Product category:
Mechanical fasteners, fixing and joining, and equipment
News Release from: Arnold Umformtechnik | Subject: Taptite thread-forming screws
Edited by the Manufacturingtalk Editorial
Team on 14 March 2007
Selecting thread-forming screws for Al
components
A comprehensive study into the design and performance of thread-forming screws in aluminium alloy distributor gear units has proved the capabilities of a screw design choice.
Working jointly with Magna Powertrain AG, Arnold Umformtechnik, a leading manufacturer of intelligent fastener solutions, has carried out a comprehensive study aimed at measuring the requirements of thread-forming screws combined with aluminium alloys The world's leading manufacturer of distributor gear units has proved the capability of this screw profile in the form of Arnold's cost-busting Taptite 2000 when used in light-metal gear housings
This article was originally published on Manufacturingtalk on 20 Feb 2004 at 8.00am (UK)
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Fastener gives anti-cross threading geometry
A spherical point at the end of a rotating fastener's shank locates the tapped hole and provides proper alignment to ensure a positive thread engagement.
Thread forming screws make assembly easier
Thread forming screw geometry allows the mating material to flow much easier and closer to the core of the screw, at a much reduced installation torque and giving an improved clamping force.
The results of the study confirm the trend that thread-forming versions will soon be strong challengers to their metric equivalents.
The comprehensive screw-in tests demonstrably indicate a relatively even pre-tensioning force window for both initial and repeat screw fastenings.
Even at maximum core hole tolerance the method achieves acceptable breakaway moments.
And under the effects of temperature too the thread-forming screws are able to substantiate their capability.
Despite widely varying temperatures the fall in pre-tensioning force on the distributor gear unit housing remains at a low level.
Furthermore, the triangular profile of the Taptite 2000 reduces tapping torque to a reliable 12Nm.
According to the two people who conducted the study, Christian Hinteregger of Magna Powertrain, and Thomas Jakob of Arnold, optimised aluminium alloys - such as GD-AISi9Cu3 - provide an excellent thread-forming structure, which, together with the triangular shaft cross-section of the Taptite system, creates low tapping torques and high overtorques.
The separation achieved between these two parameters ensures high and at the same time lightly dispersed pre-tensioning forces.
The study shows that in the distributor gear unit application in question, a thread-forming Taptite 2000 screw can replace a metric screw without problem.
And when it comes to assembling gear units and engines, the Taptite screw plays a full part in providing processing and cost benefits.
* About Arnold - the Arnold Group is a wholly owned subsidiary of the Wurth Group, which, with over 54,000 employees and with 370 companies world-wide operates on a global basis with earnings of over EUR 7.7 billion.
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