8 Popular Fastener Finishing Treatments

Fasteners are used to fasten things ranging from toys to containers.  Fastener finishes are often done to provide a decorative finish, as well as improve their resistance against corrosion. Also the surface finishing treatments will help reduce failures of fasteners in various environments.  In this post, we will discuss 8 popular fastener finishing and coating types.

Types of Fastener Finishing Treatments

The trends in fastener finishing vary across industries. For example, fasteners that are used in cars and other automobiles are exposed to high physical stress levels and extreme temperatures. However, fasteners used in food and pharmaceutical applications need to withstand daily cleaning. Hence depending upon the usage there are various kinds of fastener finishing and coating types available in the market. They are as follows:

  1. Anodizing: A thin, transparent oxide layer is created on the fastener by electrolytic passivation. The oxide layer provides excellent adhesion for secondary processes like coating.
  1. Black Oxide: This treatment is performed over stainless steel and ferrous metal fasteners to produce a black finish. During the process, the fasteners are dipped into the oil which improves it’s corrosion resistance. 
  1. Zinc electroplating: This treatment involves the depositing of zinc coating over the metallic surface by immersing it in a plating bath and passing an electric current through it. The zinc electroplating improves the visual brilliance of fasteners. 
  1. Dip-Spin Coatings: As the name suggests, a fastener is placed in a mesh basket, dipped in coating solution and spun to remove excess coating. This finishing treatment helps in improving the corrosion resistance of fasteners.
  1. Chromate Coating: Zinc and aluminum fasteners require chromate coating to improve their resistance against corrosion. This treatment helps minimize their surface oxidation.  It is commonly used for adhesive applications due to the excellent bonding properties it provides.
  1. Hot Dip Zinc: The finishing produces a heavier and an irregular coating in the thread roots and internal corners of the metals. It involves dipping the metals into pure molten zinc. The process also provides a distinct advantage over other corrosion protection methods. 
  1. Iridite: For the zinc and cadmium coated metal part, iridite coating produces a protective chromate conversion film for additional corrosion protection. This coating has an olive drab or a dull gray. 
  1. Passivation: This process produces a passive corrosion-resistant finish. It involves dipping the stainless steel parts in nitric acid, which in turn removes the particles, and brightens the finish.

The aforesaid methods aid in accomplishing a better finishing treatment for the fasteners. Fastener finishing has been catching up with the advancements in the fastener types and sizes with the specifications varying across industries. If you wish to invest in high quality finishing treatments, you can consider a reputed service provider like Norwood Screw Machine. The company provides custom fasteners in various surface finishing treatments, which are recommended on the basis of their application, and operating environment.

About Norwood Screw Machine

Norwood is a privately owned custom screw machine parts manufacturer. For over 59 years we serve some of the largest corporations to the small company with a new product to develop. Whether a unique item with a one time requirement or a long running contract order with scheduled deliveries, Norwood Screw Machine Parts is the right choice for the job.


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