Silver-Lube® Corrosion resistant bearing units

Graph 1Retention of Strength (%)Strength Retention After6 Months in WaterTemperature of Water (ºC)23 32 49 54 66 77 85110100908070Valox ® 420073 90 110 130 150 170 185Temperature of Water (ºF)WATER AND STEAM RESISTANCESilver-Lube ® housings are suitable for use in applications wherefrequent washdown occurs. After continuous immersion in water,Valox ® 420 resin exhibits very little loss of strength at watertemperatures up to (65°C) 150°F. Higher temperatures may beendured on an intermittent basis, but are not recommended forcontinuous use due to the associated loss of housing strength,see graph 1.Silver-Lube ® housings are not recommended for prolongedimmersion in, or extended exposure to, water vapour. In applicationswhere prolonged water vapour exposure occurs, some loss ofhousing strength may result. For more information, please contact NSK.Graph 2 Tensile Strength VersusTemperature (Valox ® 420 resin)Stress (psi)30000207Valox ® 420200001381000069Stress (N/mm 2 )ULTRAVIOLET RESISTANCEValox ® 420-1001 (natural coloured) resin has been tested forresistance to ultraviolet ageing by exposure to direct sunlight inFlorida and in Arizona for five years.Valox ® 420-1001 retained approximately 75% of its originalstrength, toughness and flexibility after five years of Florida andArizona exposure.0 100 200 300Temperature (ºF)Table 8(-18) (38) (93) (149)Temperature (ºC)BEARING OPERATINGTEMPERATUREHousing Temperature/Strength FactorsHOUSINGTEMPERATURE/STRENGTHFACTOR–20°C 1.00–10°C 1.000°C 1.0010°C 1.0020°C 1.0030°C 0.8540°C 0.7550°C 0.6560°C 0.5570°C 0.5080°C 0.4590°C 0.40HEAT RESISTANCEThe operating temperature range of Silver-Lube ® Valox ® 420 resinhousings is –20ºC to +90ºC.Higher temperatures may be endured for short periods, for exampleduring cleaning. However, where peak temperatures exceed +100°Cfor an extended period, please contact NSK.The maximum housing loads published in this catalogue are basedon tests conducted at 20°C. The tensile strength of Valox ® 420 resinvaries with temperature, see graph 2, above.Designers and end-users must ensure that housing strength isadequate at the unit operating temperature by adjusting thepublished housing strength at 20°C, detailed in tables 9, 10, 11 and12 by using the ‘Housing Temperature/Strength Factor’ listed intable 8. For example, the maximum housing load for a bearingoperating at 40°C is 0.75 of the published maximum housing load at20°C.When evaluating housing strength it is important to establish thebearing operating temperature and not to consider the ambienttemperature alone. Bearing operating temperature is dependent onambient temperature and bearing load and speed. For high speedapplications bearing temperatures in excess of 60°C are notuncommon. Please consult NSK in case of difficulty.10