Plating puts a thin layer of one metal onto another, which is what stands between a steel part and rust.
Electroplating also buys wear resistance, electrical conductivity and reflectivity, so the coating gets chosen around the job rather than the look.
Tell us the environment the part lives in and the salt spray hours the build has to meet, and we will match a coating to it.
For advice or more information call us today on +44(0)1827 712910 or email us at sales@coler.co.uk
Zinc, Nickel and Chrome Plating
Metal electroplating is a technical but intriguing process where a thin layer of metal is coated onto another metal surface. This technique has several benefits, including improving appearance, resistance to corrosion, and electrical conductivity.
The process starts with the thorough cleaning of the metal to be plated, known as the substrate. Any dirt, grease, or oxidation on the substrate can affect the quality of the electroplating, so this step is crucial. Once cleaned, the substrate is immersed in a chemical bath containing a solution of the desired plating metal, such as gold, silver, or copper.
Next, an electric current is applied to the bath. The substrate acts as the cathode (negative electrode) and the metal for plating acts as the anode (positive electrode). When the current flows, metal ions from the solution are attracted to the substrate and begin to deposit on its surface, creating a thin and even metal coating.
The thickness of the plating depends on how long the substrate is left in the bath and the strength of the electric current. After achieving the desired thickness, the substrate is removed from the bath and may undergo further processes, such as rinsing, drying, and polishing, to enhance the finish.
Electroplating is widely used in various industries for different purposes. In the automotive industry, it's used to plate parts for both aesthetic and protective reasons. In electronics, it's used to plate components for improved electrical conductivity and resistance to corrosion.
Plating sits alongside anodising and blasting on our finishing services line, so parts leave finished rather than going out to a separate plater.
Plating
Wet Plating
Wet plating is a technique where an object is submerged in a liquid solution to initiate the plating process through electrolysis and chemical reactions. This method primarily encompasses electrochemical plating and chemical plating.
Electroplating
This method involves dipping metal objects into a solution that contains metal ions intended for plating. The metal ions are then deposited onto the surface of the metal through direct current electrolysis.
Key properties of the electroplated layer include its appearance, thickness, porosity, corrosion resistance, hardness, and internal stress. The quality of the finishing on the electroplated parts and the conditions under which electroplating is done largely determine the appearance of the final product. The thickness of the plating is a function of the current intensity and the duration of electrolysis. The hardness and internal stress of the plated layer can vary based on the additives used and the specific plating conditions.
Chemical Electroplating
Chemical electroplating involves coating the surface of various materials with metal ions using a reactive plating solution. This process employs reducing substances and metal ions but does not require the use of electricity.
Dry Electroplating
Dry plating encompasses methods such as vacuum electroplating, vapor phase electroplating (also known as vapor deposition), and melt electroplating.
Vacuum Electroplating
Vacuum electroplating is a process where metals or chemicals are heated or evaporated under high vacuum conditions. This process allows evaporated atoms or molecules to coat electroplated items, forming a thin film of metal or chemicals, typically less than 1μm thick.
Vapor Phase Plating
Vapor phase plating is a technique that involves creating metal coatings by thermally decomposing or reducing metal halides and carbon-based compounds. Despite its effectiveness, this method requires complex equipment, incurs high costs, and operates at high temperatures using potentially hazardous chemicals. Additionally, it involves heating the materials to be plated. Due to these factors, vapor phase plating is typically reserved for specialised applications.
Melt PlatingThis method involves dipping items that need plating into molten metal and then lifting them out to form a metal film on their surface. When employing this technique, it's important to use materials with a melting point higher than that of the metals being used for plating. This requirement limits the choice of metals and alloys available.
Most of what we plate is our own work: fasteners and spacers, banjo bolts and metal pressings. Tell us the salt spray hours the build has to meet and we will match a coating to it.
Methods for Removing Electroplated Layers
Various methods exist for removing electroplated layers, each suitable for different types of materials and settings. Here are some of the most common techniques:
Abrasive Blasting: Utilising abrasive blasting machines, like those found in automobile beauty stores and construction shops, can effectively remove chrome plating layers. Techniques such as sandblasting and shot blasting, which employ micro particle powder or fine particles, are often used. However, these methods may leave hard-to-reach areas untreated, requiring separate attention.
Ultrasonic Cleaning: Specialised for cleaning delicate items, ultrasonic cleaning machines can also be effective in removing chrome plating, especially when used as a follow-up to other methods. Items are submerged in a cleaning solution, often just running water, and the ultrasonic waves help loosen and remove the chrome coating.
Hydrochloric Acid: Being a highly corrosive strong acid, hydrochloric acid can strip away chrome coatings from metal items. A concentration of 30-40% is usually sufficient, but caution is advised due to its corrosive nature.
Sodium Hydroxide Solution: This strong alkali, also known as an alkaline solution, can dissolve metal coatings like chrome. However, it reacts dangerously with water and aluminium, producing flammable hydrogen gas and corroding aluminium products. Therefore, it should only be used on materials without aluminium.
Reverse Plating: This process involves using electroplating in reverse. Chrome binds to metal at the molecular level through electric current during plating. By reversing this process, the chrome layer can be removed. However, this technique involves electrical hazards and toxic byproducts, such as hexavalent chromium, and should only be performed by professionals.
Oven Cleaner: Some types of chromium plating, particularly on plastic surfaces like automobile models, can be removed with commercial-grade oven cleaners. These potent degreasers, available in foam or liquid forms in spray cans, are applied to the chrome-plated parts. After waiting for about 10 minutes, the chrome coating can be wiped off with the cleaner.
Each method has its advantages and potential risks, so it's crucial to choose the appropriate technique based on the material and the specific requirements of the job at hand.