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Identification & Functionality
- Technologies
- Product Families
Features & Benefits
- Ready-to-Use Product Features
- Product Highlights
The Vitro-Lube process offers reproducibility and quality assurance never before attained in the industry. This is a must if the designer is to rely on a thin film as the only means of lubrication in a particular device or system. Vitro-Lube NPI-1220 is a high load lubricant and is composed of lubricating pigments in a ceramic binder, and carried in a common solvent. It is fired for a short period of time in a high heat recovery kiln until the surface of the lubricated part reaches 975°F and held there for one minute. A top coat of MoS₂, graphite and a phenolic resin is then applied and cured for one hour at 300°F. Vitro-Lube NPI-1220 is supplied only as a finished material that is applied to customer furnished hardware by NPI.
Changes to the basic 1220 formula have been attempted both with the base coat and the top coat. The most successful modification was found to be a slight change to the top coat requiring a cure of 575°F with no change to the base coat. This became our Vitro-Lube NPI-1220C in 1995 and provides significantly longer wear life as well as significantly lower overall friction.
Applications & Uses
- Markets
- Applications
- Application Area
- Intended Use
As originally conceived, the Vitro-Lube coating was intended for use as a high temperature lubricant (to +650°F) in plain journal (bushings) and plain spherical bearings applications involving low velocity oscillatory motion at high units stress loads (10,000 to 50,000 psi). It was to be used in applications where more conventional grease type lubricants or TFE liners were not suitable either because of temperature limitations or other design considerations. As more test data was accumulated, the exceptional cryogenic and room temperature capabilities of the coating became apparent and its use is no longer limited to high temperature applications. The very stringent quality control necessary for the manufacture and processing of this coating provides a more reliable product in applications where conventional resin bonded coatings have been used in the past. Vitro-lube is that very unique lubricant that should be specified after the greases, TFE liners, and conventional dry film lubricants have proven inadequate.
- Suggested Applications
The following list indicates some of the successful applications for Vitro-Lube:
- Gimbal bearings
- Flex duct bearings
- Journal bearings
- Acme screw threads
- Slides
- Ramps
- Hinges
- Splines
- Shafts
- Bushings
- Gears
- Ball screws
- Rolling elements
- Static pins
- Reverser linkage
- Latches
- Rollers
- Clevises
- Threads,
- Seals
- Poppets
We do not infer success in all applications, but we can state that if a solid film dry lubricant will satisfy your requirements, Vitro-Lube would be the lubricant most likely to provide optimum performance over a wide temperature range and substantially longer wear life.
- Metal Substrate Selection
The selection of a compatible material to accommodate Vitro-Lube has never posed a problem as it lends itself to almost all metals common to the airframe and engine industry today. For best results, we suggest a hard, reasonably smooth surface (RHR 32) that in itself possesses the required corrosion resistance.
- Clearance
When mating parts of an assembly are to be coated with Vitro-Lube, such as a plain journal bearing and it’s mating shaft, a minimum clearance of .0005″ should be maintained. The end of the shaft and the inside edge of the bushing should be radiused to facilitate assembly without damage to the Vitro-Lube coated wear surface.
- Environment
Vitro-Lube was originally developed for a maximum temperature environment of 630°F; however, we feel it is within its capabilities to be specified for environments up to 900°F, although wear life will be significantly reduced. It has been exposed to cryogenic temperatures and sodium vapors with no apparent deleterious effect. Vitro-Lube has an established compatibility with the space environment as it remains stable in a hard vacuum; it does not volatilize or outgas. Vitro-Lube has been certified as non-impact sensitive.
- General Design Suggestions
- Vitro-Lube should be applied to both mating wear surfaces whenever possible for maximum wear life. Coating of both surfaces increases wear life by a factor of three based on a number of test procedures
- Where used to prevent fretting or in a static pin joint, Vitro-Lube may be applied to only one surface
- Where only one surface can be coated it should be applied to the continuously loaded member
- To order the application of Vitro-Lube to a specific area of a detail part, the following must be shown on the manufacturing drawing: Apply Vitro-Lube NPI-1220 to the area shown. Source: National Process Industries, 42250 Baldaray Circle, Temecula, California 92590
- In those cases where a company specification exists, that shall be the controlling document. Companies that have prepared their own specifications include: Arrowhead Products, Astro Aerospace Northrop Grumman, Boeing, Boeing Integrated Defense Systems, Lockheed Martin, MD Robotics, Aerojet Rocketdyne and Raytheon (Hughes).
Properties
- Typical Properties
- Appearance
In its finished form, Vitro-Lube is similar in appearance to more conventional dry film lubricant coatings. It is dark gray to black with a matte finish. It is a continuous smooth coating that burnishes readily when handled.
| Value | Units | Test Method / Conditions | |
| Thickness | 0.0005 - 0.0009 | inches | — |
Technical Details & Test Data
- Cure Cycle
The heating cycle required to bond the Vitro-Lube base coat to the metal surface is critical and consequently very precise. In order to soften the ceramic frit and allow proper bonding, the surface of the coated part is brought to a temperature of 975°F and held for one minute. This is accomplished in high heat recovery kilns in an oxygen atmosphere. Failure to reach the proper temperature will prevent adequate softening of the ceramic frit causing a total lack of adhesion. Excessive time at temperature can result in burning of the coating which causes a degradation of the coating and a loss in wear life. The top coat is subsequently applied over the base coat and cured for one hour at 300°F for the NPI-1220 and 575°F for the NPI-1220C.
- Contaminants
For optimum results, contamination of the Vitro-Lube coated bearing surface should be avoided. Abrasive substances such as sand or metallic powder (from grinding) will definitely shorten the wear life of the coating. Fluids of any type that are on the coated surface during motion of the part will seriously degrade the wear life of the coating. This is true of all known dry film lubricant coatings and Vitro-Lube is considered to be less affected than most other dry films. The coating will withstand immersion in all fluids common to aircraft and space vehicles without washing off. No significant damage will result provided the fluids are removed prior to use. Some fluids used in typical machining operations are especially harmful to the coating and extreme care should be taken whenever any type of machining is contemplated on parts that have been coated with Vitro-Lube (such as machining of outer races of swaged plain spherical bearings).