WS2 coating brings 'relief' to punctual precision tooling

Citation

(1998), "WS2 coating brings 'relief' to punctual precision tooling", Industrial Lubrication and Tribology, Vol. 50 No. 6. https://doi.org/10.1108/ilt.1998.01850fad.026

WS2 coating brings 'relief' to punctual precision tooling

WS2 coating brings "relief" to punctual precision tooling

Keyword: Coatings

Tungsten Disulphide (WS2) was developed by NASA as a lubricant coating for the Mariner deep space probes (see Plate 12). The low friction coating is factory applied at ambient temperature to form a molecular bond with the substrate material, which can be metal or plastic. The coating cannot chip or peel. Parts need no special engineering as its 0.5 micron thickness is well within the normal engineering limits of fit. The material does not bond with itself so cannot be "built up". Small holes, slots and fine surface detail can be coated. Ball and roller bearings can be coated in the assembled condition. Linear slides and recirculating ball screws may need to be dis-assembled, coated, then re-assembled, which can be carried out at the processing factory. The coating is claimed to enhance the performance of conventional lubricants on applications such as machine tool spindles, bearings, liner slides, actuators, valves, gears, internal combustion engines, pumps, cutting tools, and will tolerate high vacuum conditions and high temperatures. The coating may be used in clean room environments, for food processing equipment, and as a release agent for investment casting cores, zinc casting dies and plastic moulding, and in metal-to-metal contact situations to reduce friction, wear, fretting, galling (especially stainless steel on stainless steel), seizing or lubricant contamination.

Plate 12 Example of unscrewing sleeve coated with WS2

Many examples of performance improvement in practice are quoted. For example, Punctual Precision Tooling of Horsham have reported a series of remarkable improvements following the coating of mould parts with WS2 tungsten disulphide dry lubricant supplied by WS2 coatings Ltd. One of the latest of these concerned the significant response from the tools they manufacture for producing Lever Brothers "Comfort" fabric conditioner bottle closures. A number of six-year-old 12-impression unscrewing tools that were beginning to show their age had been returned to the factory for refurbishment; the main problem being that parts being produced were sticking in the mould. This was solved by having the central steel cores and the beryllium copper unscrewing sleeves from the mould coated with WS2, which was offered by WS2 coatings on a same-day basis. Other users of the effect of the WS2 coating on unscrewing cores reported significant reductions in cycle time, e.g. from 21 seconds to 17 seconds, together with a reduction in the torque required to unscrew the cores. Quality was also improved and downtime reduced.

Modified tungsten disulphide (WS2) in laminar form has a coefficient of friction of 0.030 (dynamic) and 0.070 (static) and lubricates up to 650°C. It is inert, non-toxic, and will not chip or peel. At 0.5 microns thick it requires no engineering changes to mould parts.

Further information from: Steve Hall or Dave Clark at WS2 Coatings Ltd. Tel: +44 (0)1430 861222; Fax: +44 (0)1430 861110.