Unasis XtrMD coating is a Molybdenum disulphide based coating which can be applied to a variety of components.
Molybdenum disulfide (MoS2) is a naturally mined inorganic material which has become extremely popular as a dry film lubricant due its availability, price and advantages over comparable dry film lubricants. By reducing the coefficient of friction, moly disulphide can increase speed capacity and increase the life by acting as a sacrificial lubricant which will coat all surfaces.
However it is possible that in ultra high vacuum applications if the bearings are running at high speed the coating may create small particles which will contaminate a vacuum. Molybdenum Disulphide
coating can be applied to stainless steel hybrids.
|Molybdenum Disulphide||Tungsten Disulphide|
|Colour||Blue-Silver Gray||Silver Gray|
|Appearance||Crystalline Solid||Crystalline Solid|
|Density||7500kg m-3||5060kg m-3|
|Thermal Stability in Air||COF < 0.1 310oC||COF < 0.1 600oC|
|Coefficient of Friction||0.16 Dynamic, 0.19 Static||0.03 Dynamic, 0.07 Static|
|Chemical Durability||Inert, Non-toxic, Non-Magnetic||Inert, Non-toxic, Non-Magnetic|
|Corrosion Resistance||Will not prevent corrosion||Can slow corrosion but will not completely prevent corrosion|
Heavier and more stable than Moly disulphide, tungsten disulphide has been extensively used throughout a number of NASA, military and aerospace applications. With an even lower friction coefficient and ability to slow corrosion on some materials tungsten disulphide has been the coating of choice for a number of high-end applications and used as a solution to issues such as excessive wear, seizing, galling and fretting.
The coating itself once applied is only 0.5microns thick and will not bond to itself negating issues such as build up. Like moly disulphide, tungsten disulphide is inert, non-toxic and nonmagnetic but unlike moly will not cause particulate contamination of an ultra high vacuum. Tungsten disulphide can be used to coat hybrid bearings.
Greases and Oils
Grease and Oils are standard lubricants applied to the majority of bearings in order to increase lubrication and decrease wear on rolling elements but can be altered in order to meet the demands of various applications.
All Unasis hybrid bearings can be greased to suit specific application requirements. For special requirements grease specification can be changed. Whether it is for a high temperature, high load or high speed application they all demand very different requirement from their lubricants. Grease and oil lubricants can also be added to full ceramic bearings as well as hybrids in order to change performance characteristics such as increase speed, reduce ball skidding or reduce noise. Grease specifications are subject to application in order to decide which grease type is most applicable to your application contact Unasis sales team.
XtrPoly fills the space between the rolling elements and races in a bearing, providing constant and consistent lubrication. There is no need for additional lubrication during the life of a XtrPoly filled bearing. Because it is a solid, XtrPoly can help block debris and reduce foreign contamination of the bearing.
Reducing the incursion of debris into the bearing can significantly extend the bearing’s life. The solid structure of XtrPoly also makes it suitable for environments where grease and oil leakage cannot be tolerated, as it will not drip out of the bearing and contaminate the environment.
XtrPoly filled bearings have speed limitations lower than standard oil or grease lubricated please contact Unasis for information on your specific size of bearing.
Filling bearings with XtrPoly does not change the dimensional tolerances of the bearing in any way it simply fills the spaces between the rolling elements and the cage.
XtrChrome Coated Bearings
XtrChrome is a thin dense chrome coating applied to the bearing components in a process which ensures precise coating deposit giving a satin chrome surface finish. The process offers many advantages including corrosion resistance, increased bearing life, cost reduction, reduced production lead time and energy saving properties due to reduced surface friction XtrChrome is used across a variety of industries including aerospace, naval, oil & gas, semicon, chemical, pharmaceutical and food processing.
It is particularly useful as a coating for bearings and bearing surfaces made of 52100, M-50, M-50 NIL, BG-42. 440C, and all pH basis metals. XtrChrome enables bearing surfaces to run longer and cooler. US Airforce tests have shown that XtrChrome enhances both ball and roller bearings and does not affect or induce fatigue or change base metal characteristics.
The surface texture gives exceptional performance in extreme environments especially if used in conjunction with ceramic rolling elements. The nodular microscopically surface holds lubrication within the surface structure giving advantages in the following environments: Fast acceleration without full ball loading, oscillating movements which do not complete a full revolution, emergency rundown due to loss of lubrication, low rotational speeds, environments which do not allow for lubrication. Speeds capabilities at lower operating temperatures are significantly increased.
Fretting corrosion which is caused by micro displacement of the bearing rings can be greatly reduced.
XtrChrome Coating Benefits
- Corrosion resistance exceeding 440C stainless steel, with additional chemical resistance
- Increased wear resistance due to 78HRC surface hardness
- Reducing wear and friction in application
- Absolute adhesion to basis metal: no chipping, cracking, flaking or peeling
- Reduced maintenance and part replacement costs
- Longer running capabilities with lower coefficient of friction
- FDA approved for product contact
- Nodular surface gives better adhesion strength of lubrication film
- Reduction of microweld adhesion
- XtrChrome coated components are more economic and readily available the 440C Stainless Steel
For more information please contact us »