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Lead screws go nuclear

Product News Monday, February 14, 2011: ABSSAC LIMITED

Abssac limited has long been associated with supplying products into the nuclear physics industry and has recently maintained this trend by supplying lead screw and nut assemblies for use within a high vacuum diagnostic tool for particle accelerators.

The leadscrew assembly was used to accurately displace two disk like structures that captivated a precision aperture, which in turn shaped a supersonic gas jet passing through them. Changing the distance between the disks, enabled the tailoring of the shape of the gas jet for diagnosis purposes. Finite repeatable linear accuracy, reliability and required to continuously work in a vacuum environment of 10-6 mbar, were some of the criteria of the application.

The high vacuum environment also meant that out-gassing of the plastic materials employed for the nut could pose a problem to final diagnostics. After some consultation with various material suppliers., the material chosen for the nut was Toray Torelina PPS resin with GFRP. (TORELINA* Polyphenylene Sulfide). This high-performance engineering plastic TORELINA* resin provided excellent heat resistance, flame retardancy , chemical resistance and physical strength.

Abssac was also able to supply the 2mm pitch flanged nut already degassed and certified using a GCMS (Gas Chromatograph Mass Spectrometer) which recorded the emitted compounds by mass number on a certified calibrated graph. After a 2 hour treatment and subsequent GCMS analysis the nuts were ready to be fitted to the 6mm diameter stainless steel screw and shipped in a sealed atmosphere packaging.