This technical information has been contributed by
Nimet Industries

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Composite Coating Dramatically Increases Lubricity
coatings
Teflon-rich autocatalytic nickel plating can be used on a range of substrates.

A leading computer manufacturer had a costly production problem. Small metal screws frequently snapped as they were inserted into electronic components. That meant removing the incomplete assembly from the clean room, repairing it and then preparing it for reentry into the clean room environment.

The solution was to coat the screws with NiCoTef, a high lubricity coating that dramatically reduced the amount of force required to insert the screws. For the manufacturer, the result was less breakage, faster assembly and lower production costs.

How the Process Works

NiCoTef, a new composite coating process available exclusively from Nimet Industries, imparts the following properties to a wide range of ferrous and nonferrous substrates:

In the coating, submicron particles of Teflon are dispersed throughout an autocatalytically applied nickel/phosphorous matrix.

The composite Teflon/nickel/phosphorous coating is deposited through a controlled chemical reduction catalyzed by the metal ahoy being deposited. Because the process does not require electrical current to sustain deposition, the coated part does not exhibit the difference in deposition thicknesses caused by current density variations in electroplating processes.

The uniform coating thickness achieved by NiCoTef makes the process extremely cost-competitive with alternative processes for parts with complex configurations where uniform coating and high lubricity are desired.

Composition

NiCoTef, which incorporates Teflon at 23-25%, yields a lower coefficient of friction than is provided by most conventional coatings.

Because the Teflon is codeposited with the nickel/phosphorous rather than applied to the surface in a subsequent operation, a continuous supply of PTFE (polytetrafluoroethylene) is provided throughout the life of the coating.

Applications

NiCoTef should be considered as a protective coating when these results are desired:

NiCoTefs combination of lubricity, uniform coating thickness and corrosion resistance makes it especially suitable for: valves; fluid power systems; carburetor, brake, engine and fuel injection components; pumps; bearing and material handling surfaces; small gears; cylinders; molds and dies; mixing blades; computer components and many other applications in industries ranging from aerospace and automotive to printing, textiles, electronics and chemical processing.

The coating can be successfully applied to most metals, including iron, carbon steel, cast iron, aluminum alloys, copper, brass, bronze, stainless steel, high alloy steels, and high nickel alloys.

For maximum coating performance, surface conants and imperfections must be removed before plating. If not eliminated, these flaws will result in poor coating adhesion and reduced resistance to corrosion or wear.

Proper coating application begins with an evaluation of the substrate, followed by the chemical cleaning and activation processes required to produce the optimum results for each situation.

Quality Control

In Nimets application of NiCoTef, strict processing and quality assurance procedures are used for each lot of parts. Critical dimensions are verified before, during and after processing. Sampling is per MIL-STD-105,1-1/2% AQL unless otherwise specified. SPC methods are available for continuous large-lot processing.

This stringent quality control assures scrupulous preparation of the substrate, frequent monitoring of the plating bath composition, and close dimensional control during processing for the best possible coating adhesion and part performance.

Sample Processing

To see how NiCoTef will perform on a particular substrate, it is recommended that a prototype representative of the parts to be treated should first be submitted for processing. The sample can the be evaluated for coating adhesion, porosity and performance under the conditions of the application.

For the most satisfactory results, specifiers should provide blueprints and complete information, including the application for which the process is intended, the performance environment, the desired results, critical dimensions and tolerances, and areas which are to be masked.

Nimet Industries provides finishing services for demanding applications in medical instrumentation, aerospace, ordinance and many other industries. The firm's extensive experience includes the development and application of the low-friction coating Nituff a proprietary process which penetrates Teflon.

NiCoTef is a registered trademark of Nimet Industries
Teflon is a registered trademark of DuPont

This technical information has been contributed by
Nimet Industries

Click here to find suppliers

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