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Process

Electroplating is the application of metallic coatings to metallic or other conductive surfaces by electrochemical processes.

Electroplating is both an art and a science. Although based on several technologies and sciences, including chemistry, physics, chemical and electrical engineering, metallurgy, and perhaps others, it retains in some ways the aspects of an art, in which experience is the only teacher. In fact, of course, all the sciences have elements of art which can be learned only by experience; all the reading of textbooks on chemistry will not produce a chemist. No text on electroplating will produce an expert electroplater; there is no substitute for experience and what is somewhat inelegantly termed know-how.

Anodising

Anodising is an electrolytic passivation process used to increase the thickness of the natural oxide layer on the surface of metal parts.

The process is called anodising because the part to be treated forms the anode electrode of an electrical circuit. Anodising increases resistance to corrosion and wear, and provides better adhesion for paint primers and glues than bare metal does. Anodic films can also be used for a number of cosmetic effects, either with thick porous coatings that can absorb dyes or with thin transparent coatings that add interference effects to reflected light.

Anodising is also used to prevent galling of threaded components and to make dielectric films for electrolytic capacitors. Anodic films are most commonly applied to protect aluminium alloys.

Anodising changes the microscopic texture of the surface and the crystal structure of the metal near the surface. Thick coatings are normally porous, so a sealing process is often needed to achieve corrosion resistance. Anodised aluminium surfaces, for example, are harder than aluminium but have low to moderate wear resistance that can be improved with increasing thickness or by applying suitable sealing substances. Anodic films are generally much stronger and more adherent than most types of paint and metal plating, but also more brittle. This makes them less likely to crack and peel from aging and wear, but more susceptible to cracking from thermal stress.

Anodising is available as rack only.

Enquire about our full colour range

Iridite (a replacement for Alocrom 1200)

Iridite NCP is an innovative new process that offers extremely high resistance to corrosion, tested to 1000 hours on many aluminum alloys. Iridite NCP also has the ability to withstand high temperatures, so it is suitable for use on items with high operating temperatures such as automotive engine components and electronic heat sinks. This unique property, not found in chromates, also allows applicators to increase the temperature of their dry-off ovens prior to painting increasing throughput and productivity. Unlike traditional Chromate treatments that require up to 24 hours to cure to a hard film, lridite NCP provides a hard amorphous crystalline coating as formed.

Key Features

  • Bare corrosion resistance without painting, even after heating or baking
  • Excellent adhesion to paints, sealants and adhesives
  • Environmentally compliant – contains no hexavalent or trivalent chromium compounds
  • Simple application using spray, immersion or flood methods
  • Drop in replacement for chromating – no line modifications needed

Corrosion Performance

Aluminium
Alloy

Salt Spray
Hours

Iridite
NCP

Chromate

5052

 

1000+

1000+

6022

 

1000+

1000+

3003

 

1000+

168

1100

 

1000+

432

6111

 

1000+

432

6061

 

1000+

648

A356

 

576

1000+

Electrolytic Nickel Plating

Electrolytic nickel plating, also known as nickel electro-deposition, is becoming an increasingly popular process for a variety of different manufacturing applications. Electro nickel plating is a process that uses an electrical current to coat a conductive material, typically made of metal, with a thin layer of nickel.

In general, electroplating improves a wide range of characteristics not inherently present in the base material. Some of these benefits include:

  • Increased resistance to corrosion
  • Improved hardness
  • Superior strength
  • Resistance to wear
  • Improved ductility

Nickel is considered useful for electroplating metal items because it provides superior ductility, corrosion resistance and hardness. Electro nickel plating can also improve a products brightness and external appearance. Different nickel-plating chemicals incorporated into the process deliver anything from a semi-bright and fully bright cosmetic effect, to matt, pearl or satin finishes.

Electroless Nickel Plating

Electroless nickel plating is an auto-catalytic reaction used to deposit a coating of nickel on a substrate. Unlike electroplating, it is not necessary to pass an electric current through the solution to form a deposit. This plating technique is to prevent corrosion and wear. Electroless nickel plating has several advantages versus electroplating, free from flux-density and power supply issues, it provides an even deposit regardless of workpiece geometry.

Advantages include:

  • Does not use electrical power
  • Even coating on parts surface can be achieved
  • No sophisticated jigs or racks are required
  • There is flexibility in plating volume and thickness
  • The process can plate recesses and blind holes with stable thickness
  • Chemical replenishment can be monitored automatically
  • Complex filtration method is not required
  • Matt, semi-bright or bright finishes can be obtained

Copper Plating

Copper plating, although traditionally used for electroforming or decorative purposes, copper is an excellent conductor and copper plating can be used for EMI (Electro Magnetic Interference) and RFI (Radio Frequency Interference) shielding purposes.

Our copper plating can be coated with anti tarnish which has been developed to remove the use of additional top coat plating ie. silver plate. Designed for use with microwave and RF technology.

The deposit from copper plating is very bright and has excellent levelling properties. One typical application for copper plating is for large aerials fitted under railway carriages. In addition, copper plate naturally kills bacteria, therefore, copper plating is frequently used to plate laboratory and medical equipment.

Today, copper electroplating or plating copper as a coating onto another metal is a highly refined and effective method many industries rely on. Copper's excellent thermal and conductive properties make it a particularly useful substance in numerous heating, industrial and electrical applications. Copper coatings are also commonly used in corrosion protection.

The many applications of copper plating include use as an undercoat in situations where enhanced adhesion for additional coatings of other materials is desirable as it provides smooth and uniform coverage. Copper electroplating can be used as a treatment for the preparation of surfaces for soldering. It is also common for industries such as aerospace and electronics to apply copper plating on plastic applications.

Available in rack or barrel.

Silver Plating

We undertake many different silver plated electrical components on almost all metal substrates, where silver is specified for its conductive properties. Our silver plating solutions produce a bright, semi bright and dull silver deposit of 99.9% purity. Sterling silver by comparison has a purity of only 92.5%. Bright or satin finishes are available and can be applied to many different base metals. Bright and reflective finishes can only be achieved when the pieces are polished or bright nickel plated prior to plating.

All plating is undertaken to the latest British Standards or to customer supplied plating specifications. We currently run rack and barrel plating service along with anti-tarnish if needed.

Rack & Barrel Plating

We offer both rack and barrel plating.

Rack plating – where larger parts are affixed to metal racks which are placed inside the tank. The parts remain stationary during plating. 

Barrel plating is normally used for smaller parts – the parts are placed inside a barrel and rotated in the tank, which provides a more uniform finish.

Bright Tin Plating

Tin is a silvery malleable metal that doesn't get easily oxidised in air and is used to coat other metals to prevent corrosion. The electrical and electronics industry are heavily dependent on tin and tin alloy coatings for solderability most of which is done by electroplating. Tin plated metal is also used for food packaging giving the name to tin cans which are made mostly of steel.

Tin plating is used extensively in the electrical engineering industry to provide protection and to confer solderability. Tin electroplating is also widely used in manufacturing printed circuit boards (PCBs) and electronic components. Most electronic circuit components are made by soldering therefore the surfaces of the conductors being connected are coated in tin or a tin alloy aiding solderability. Additionally tin coating protects the components and connection from corrosion in aggressive atmospheres.

Tin is one of the easiest metals to electrodeposit and one of the advantages of electroplating is that no limitation is imposed on the thickness of tin that can be applied. The required thickness can be attained by adjusting the bath parameters and time.

Tin is usually plated with a bright or matt finish. Bright tin is obtained from electroplating solutions containing brighteners, ie. organic additives causing formation of very fine grains of deposit. It has excellent cosmetic appearance. Matt tin coatings are made in electrolytes with few grain refiners, but without brighteners. It has a dull appearance but the level of internal stresses in matt tin deposits are much less than in that of bright tin.

Dull Tin Plating

Matt tin coatings are made in electrolytes without the addition of brighteners. Matt tin has a dull appearance, but the level of internal stresses in matt tin depositions is much lower than it is in bright tin depositions. Matt tin (in contrast to bright tin) is characterized by low whiskers growing, therefore, it is used in electronics.

Characteristics:

  • A dull, semi-bright or satin-bright appearance
  • Disperse reflectivity
  • Existence of grains with an average size in the range of a few microns
  • The deposit is free of the co-deposited brighteners found in bright tin plating

Our dull tin is ideal for electronic or precision components. Deposits give good solder ability even after heat or steam ageing.

Zinc Plating

Rust is the greatest enemy of just about any type of metal and its corrosive effects can be devastating.

A process known as zinc plating is frequently used to protect metals such as iron and steel against the relentless forces of corrosion. Zinc plating involves the electro deposition of a thin coating of zinc metal onto the surface of another metal object, known as a substrate. The zinc coating creates a physical barrier that prevents rust from reaching the underlying metal surface. Zinc is chosen because of its innate ability to fight corrosion. In fact, zinc is often referred to as the corrosion-prevention workhorse.

While zinc cannot quite match cadmium in terms of corrosion protection it is viewed as a more environmentally friendly alternative.

One of the most important benefits of zinc plating is that it will significantly increase the corrosion resistance of the underlying substrate. In addition to forming a physical barrier, the zinc serves as a sacrificial coating. This means that the zinc coating will corrode instead of the metal substrate that it protects.

Additionally, zinc reacts with the oxygen in the atmosphere to form zinc oxide. The zinc oxide subsequently reacts with water to form zinc hydroxide, which bonds with carbon dioxide to produce a thin layer of zinc carbonate. The zinc carbonate adheres to the zinc on the coated metal to provide even more corrosion protection.

We offer rack plating, where larger parts are affixed to metal racks which are then placed inside the tank. The parts remain stationary during plating. We also offer barrel plating which is normally used for smaller parts – instead of a plating rack, the parts are placed inside a barrel and rotated, which provides a more uniform finish.

Zinc Nickel Plating

Zinc nickel alloy plating containing 12 – 15% nickel and 85 – 88% zinc onto steel substrates is highly resistant to corrosion providing over 1000 hours of neutral salt spray from a 10-micron deposit.

The zinc nickel deposit achieves exceptional corrosion protection with high temperature resistance that meets the demands of the automotive industry even after heat treating (Thermal shock). This process also meets with the demands of European Unions "End of life vehicle directive".

The alloy gives exceptional sacrificial corrosion resistance and can be readily passivated with additional top coat sealers or torque and tension fluids.

Advantages of zinc-nickel plating processes:

  • Excellent corrosion resistance
  • Good alloy distribution
  • Excellent deposit distribution (alkaline)
  • Compatible for TriPass hexavalent-chromium free passivates
  • Friction properties can be modified with Torque 'N' Tension fluids
  • Passivations available in clear silver, clear blue and black with available top coats and sealers

Rack and barrel available.

Phosphate – Zinc & Manganese

Karas Plating offer both zinc and manganese phosphate coatings and these can be offered self-colour, ready for paint preparation and rust prevention or with additional top coatings oiled, black spirit stained and molybdenum coated.

Zinc Phosphate is mainly used for rust prevention on ferrous metal and is a lighter alternative to manganese phosphate while providing resistance to harsh elements that tend to wear products quickly. Dark grey in colour zinc phosphate is suitable for paint pre-treatment or can be supplied oiled

Manganese phosphate is a popular coating due to its hardness and wear resistance used to pre treat ferrous metal prior to painting and to increase corrosion resistance. The coating creates a heavy crystalline finish on ferrous surfaces and absorbs oil and other lubricants. Ideal for use with engine components, gears and power transmissions systems. Dark grey in colour manganese phosphate can be supplied as coated or oiled, black spirit stained or molybdenum coated.

Gold Plating & Other Finishes

Gold plating is often used in electronics to provide a corrosion-resistant electrically conductive layer on copper, typically in electrical connectors and printed circuit boards.

Gold coatings are used in engineering applications for the corrosion and tarnish resistance, solderability, wear resistance, bond ability, low and stable electrical contact resistance and infra-red reflectivity.

Gold plating finish benefits:

  • It has a high corrosion resistance
  • It does not form an oxide film on its surface and has a low contact resistance
  • The finish can be either bright or dull
  • In the electronics industry it is used for protection from corrosion to provide a conductive layer on copper or brass
  • To prevent tarnishing, nickel is deposited first to provide a base for the gold and improved wear resistance

Other services available are:

  • Shot blasting
  • Tumble blasting
  • Hand blasting
  • Passivation of stainless steel
  • Ultrasonic cleaning
  • De-greasing