Product category:
Fasteners, threaded and non-threaded
News Release from: Cross Manufacturing Co (1938) | Subject: Spiralock wire thread insert
Edited by the Engineeringtalk Editorial
Team on 13 September 2006
Wire thread inserts pass
high-temperature test
Testing proves that the Spiralock wire thread insert can withstand repeated exposure to high temperatures and vibration with virtually no deterioration in its performance.
An arduous programme of high temperature and vibration testing has proved that the Cross Spiralock wire thread insert can withstand repeated exposure to these conditions with virtually no deterioration in its free running and thread locking performance By comparison, a conventional prevailing torque insert failed completely after the very first heating and vibrating test cycle
This article was originally published on Engineeringtalk on 28 Nov 2003 at 8.00am (UK)
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The results are all the more remarkable since the Cross Spiralock insert used was a standard stainless steel version whilst the prevailing torque insert was made of expensive Nimonic 90 and silver plated.
This version is specifically sold for high temperature applications.
For the test a 0.25 UNFx1.5D insert was first fitted with an Inconel 718 bolt, tightened and vibrated on a Junkers transverse vibration rig for three minutes.
After confirming that the bolt was still locked, it was then removed and the breaking torque recorded, after which the bolt was retightened and the assembly heated to 650C for 6h.
The assembly was allowed to cool, the bolt removed and the breaking torque recorded as before.
The complete procedure was repeated five times.
Throughout the five test cycles the bolt remained locked in the Spiralock insert whilst the breaking torque increased to approximately twice the initial value before levelling out, thus proving that the bolt was not seizing-up.
In a subsequent test, an identical Spiralock insert and bolt assembly was heated to 650C and cooled five times without disassembly until the end of the test cycle.
Comparison of the breaking torque once again confirmed that the locking performance of the insert was virtually unaffected by the repeated heat cycles.
The Cross Spiralock wire thread insert is already used in various high temperature applications, including turbochargers for petrol and diesel engines.
It is hoped that these test results will give confidence to potential users in other engineering "hot spots" who may be experiencing problems with prevailing torque insert performance.
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