Coated Fasteners

PTFE Coated Fasteners

PTFE Coated Fasteners (Teflon)

PTFE is a acronym for Polytetrafluoroethylene which is a two-coat non-sticky fluropolymer coating. PTFE has the highest operating temperature among any fluoroplastic polymer. PTFE have extremely low co-efficient of friction, good chemical resistance and medium to fair abrasion resistance. PTFE is suitable as a dry lubricant with low co-efficient of friction. PTFE coated fasteners stands exceptional to Salt Spray Test. It has outstanding release capabilities and can withstand a maximum use temperature of 600°F, higher than any fluoropolymer. This coating is typically applied to a thickness of 1-3 mils. PTFE is also commonly referred by their tradename/brands, teflon, xylan, etc. These fluoro polymers makes excellent choice for agressive environment. PTFE or teflon coated fasteners are widely used in oil & gas platforms for extraction and refinning applications

Hot Dip Galvanised Fasteners

Hot Dip Galvanised Fasteners

Hot dip galvanizing is a method of coating a steel with metallic zinc to prevent it from corroding. Preliminarily the object to be hot dipped galvanized is passed through a chemical solution to remove all rust, oil & surface scales. After the cleaning, the cleaning solutions is rinsed off the surface and the steel is taken further for coating. The steel is then dipped into a bath of hot molten zinc which has been heated to a temperature of 460 ° Celcius. The steel substrate is then removed from the bath and allowed to cool in a quenching tank. When the substrate is cooled, the zinc coating is metallurgically bonded to the steel. High tensile fasteners like B7/2H, Grade 8.8, 10.9 & 12.9 are commonly Hot Dip Galvanized.

Dacromet® Coated Fasteners

Dacromet® Coated Fasteners

Dacromet® is a water based inorganic coating mainly comprising of overlapping zinc and aluminum flakes with an inorganic binder. This Zinc Aluminum flake combination offers 4 way protection: 1) Barrier Protection : Overlapping zinc and aluminum flakes provide an excellent barrier between the steel substrate and the corrosive media. 2) Galvanic Action : Zinc corrodes to protect steel. 3) Passivation : Metal oxides slow down the corrosion reaction of zinc and steel to provide 3 times greater corrosion protection than pure zinc. 4) Self-Repairing : Zinc oxides and carbonates migrate to the damaged area of the coating to actively repair the coating and restore barrier protection. Dacromet® can be applied by Dip-Spin, Spray or Dip-Drain (Spin) using bulk or rack. This type of coating is primarily used in marine, agriculture, construction equipment, wind turbine, aerospace and heavy automotives.

Zinc Phosphated Fasteners

Zinc Phosphated Fasteners

Zinc phosphate coating is a crystalline conversion coating formed on surface of the metallic fastener with reaction to mildly acidic phosphate liquid to form insoluble phosphate crystals on the surface. These phosphate fasteners can be used with or without applying oil over the surface to facilitate reduction in friction on the threaded part of the fasteners. Moreover applying oil over zinc phosphate coating can be beneficial to provide addition corrosion protection. Zinc phosphate coatings are common over carbon steel structural fasteners or alloy steel high tensile fasteners. Zinc Phosphate Fasteners appear dark grey or black in color with topcoat of oil or paint, typically used for anti galling purpose or as a basecoat for further coating formulae.

Manganese Phosphated Fasteners

Manganese Phosphated Fasteners

Manganese phosphate coating is also a conversion coating, involves dissolution of a manganese salt crystal over the surface of a metal fasteners in reaction with phosphoric acid in presence of catalyst. The final product deposited over the fastener is manganese iron phosphate which requires a large amount of metal dissolution so that the formation of mangese iron phosphate is facilitated. Manganese phosphate coating requires high operating temperature and higher processing time. Oil can apply to lubricate reducing the friction over threaded parts. Zinc Phosphate Fasteners appear dark grey or black in color with topcoat of oil or paint, typically used for anti galling purpose or as a basecoat for further coating formulae. Moreover manganese phosphate fasteners show good wear resistance. Corrosion resistance increases with quality of raw material used and scale of coating.

Zinc Plated Fasteners

Metallic Zinc Plated Fasteners

Zinc plating is identical to electro-galvanizing in principle because both are electro-deposition processes. However, zinc plating is used on small parts such as fasteners, crank handles, springs and other hardware items rather than sheet metal. The zinc is applied as an expendable electrode in a cyanide, alkaline non-cyanide, or acid chloride salt solution. Cyanide baths are the most operationally efficient but can potentially create pollution and are hazardous. After alkaline or electrolytic cleaning, pickling to remove surface oxides followed by rinsing, the parts are then loaded into a barrel, rack, or drum and immersed in the plating solution. Various brightening agents may be added to the solution to add luster, but careful control is needed to ensure a quality product. Post-plating treatments may be used to passivate the zinc surface as well as impart various translucent colors or to extend the life of the coating.

Nickel Plated Fasteners

Nickel Plated Fasteners

Nickel plating a.k.a Nickel Electroplatng is a chemical deposition method of covering a metal object with a layer of nickel. Nickel plating is usually performed for decorative purpose i.e to provide a aethethic look to the fasteners or any other object. Nickel electroplating also provides corrosion protection, wear resistance or to build up undersized or worn parts. Bolts or nuts to be electroplated are firstly cleaned to free of dirt, rust and defects before plating. Cleaning process may be a combination of heat treating, masking, pickling and etching. Once the part is cleaned, it is immersed into an electrolyte solution and is used as a cathode. The nickel rod acts as a anode and is dissolved into the electrolyte in form of nickel ions. The nickel ions travel through the solution and gets deposited over the substrate.

Chrome Plated Fasteners

Chrome Plated Fasteners

Chrome plating or chromium plating is a electrolytic method of depositing a thing layer of chromium over a metal or plastic object. Chrome plating is mainly used for decorative purpose, giving the substrate an aesthetic look. Chrome plating is less cheaper and alternative to nickel plating in terms of providing decoration. Chrome plated surface provide corrosion resistance, increased surface hardness, easy cleaning of parts, etc. Deposits can be applied from 0.25 - 1,000 microns thickness for a wide range of applications. The thinner deposits being used to substantially increase the life of components in wear applications or corrosive environments, and the thicker deposits being used for salvage and repair of worn, damaged or mis-machined components. Hard Chrome is classed as a "COLD" process, the operating temperature of 50 - 60°C ensures no detrimental effects to the physical or mechanical properties of the base materials. Hard Chrome can be deposited successfully and advantageously onto most metallic substrate materials.

Cadmium Plated Fasteners

Cadmium Plated Fasteners

Cadmium coating alike zinc coating provides sacrifical protection to steel by being prefentially corroded when the coating is damaged and the portion of the steel is exposed. Cadmium coatings are applied to iron, steel, brass & aluminum to five excellent resistance to corrosion in most conditions including marine & alkaline environments. Cadmium coatings have low coefficient of friction, good lubricity and predictacle torque characteristics, good electrical conductivity and protection from galvanic corrosion. Cadmium coatings are particularly useful in the electrical, electronic, aerospace, mining, offshore, automotives and defense industries where they are applied to bolts and other fasteners, chassis, connectors and other components. Cadmium coating is normally specified in thickness between 5 and 25 µm depending on the severity of the atmosphere. Chromate post-treatment of the coating can increase coating life.

Silver Plated Fasteners

Silver Plated Fasteners

Silver coated fasteners are produced by means of silver electroplating or silver immersion plating. In silver immersion plating method, the fastener piece is immersed in a silver solution, traded by many proprietory names. In a more effective method, called silver electroplating, metallic silver is electrochemically deposited over a fastener dipped in a electrolytic solution in the presence of a electric current. Silver plated fasteners have distinguished look over other metallic coatings but relatively higher in cost. Though it is least expensive over other precious metals. Referring to binding properties and atomic depostion process, silver plated fasteners can be thoroughly cleaned up without leaving any contamination. Excellent lubricity, etc. Silver plated fasteners find excessive use for electronics and electrical component fastening. Silver plated fasteners are costly due to high commodity prices.

Tin Plated Fasteners

Tin Plated Fasteners

Tin Plated Fasteners are well distinguished for their aesthetic looks, high degree of corrosion resistance, least toxic nature, etc. They find good use in marine fastening and food-beverage processing units. Tin is electroplated over fastener surface in presence of a electric current. The solvent contains metal solution used to extract the metallic coating over to the substrate. Tin plating can be performed over a large number of carbon steel, high tensile alloy steel, and stainless steel as well for enhance aesthetic look. Tin coating appears whitish mirror like with high corrosion resistance, no known toxicity, superior aesthetic look, excellent solderability, low cost compared to silver plating.