Services - Finishing - Passivation

Passivate leadscrews for extended service life

Maximize corrosion resistance and reduce leadscrew surface impurities remaining from processing. Remove surface contaminations, such as iron particles left by cutting tools, that can form rust or act as initiation sites for corrosion with passivation.

Origins

Generally speaking, passivation is the process of making a material passive or inert in relation to another material prior to using the materials together. The primary purpose of passivation for leadscrews is to remove surface contamination, that can foster corrosion. The thread rolling dies and cutting tools can impart these contaminants and should be removed for optimal longevity and service life of your leadscrews.

Characteristics

In the context of corrosion, passivation is the spontaneous formation of a hard non-reactive surface film that inhibits further corrosion. This layer is usually an oxide or nitride that is a few atoms thick. Under normal conditions of pH and oxygen concentration, passivation is seen in such materials as aluminum, magnesium, copper, stainless steel, titanium, and silicon.

Applications

To ensure that machined parts have optimum corrosion resistance, they should be properly passivated. Passivation can remove sulfides exposed on the surface of free-machining alloys, which also may act as initiation sites for corrosion. Increasingly, citric acid passivation has become a viable alternative to traditional nitric acid passivation, particularly in the stainless steel industry.

Note: ASTM A967 provides advice for the passivation of stainless steel parts. The conditions necessary for passivation are recorded in Pourbaix diagrams. Some corrosion inhibitors help the formation of a passivation layer on the surface of the metals to which they are applied. Passivation is not a scale-removal method. Any particles of oxide or heat tint must be removed before passivating. Passivate the lead screw to extend the service life of your motion drive assembly.

Passivation Benefits:

• Maximizes corrosion resistance.
• Dissolves contaminates from metals.
• Enhances surface appearance.
• Removes impregnated metals out of threads.