Introduction to Electroplating
An Introduction to an Electroplating process
Here we would like to help beginners understand the most important aspects of electroplating:
The Electroplating process is a method for coating (electro deposition) conductive (metal) objects with any other type of metal such as copper, nickel, gold, rhodium, chrome, silver, brass, bronze, tin, lead, zinc etc.
You will find these processes quiet simple if you know how to carry them out. The electroplating business is becoming more and more popular and there are many different ways in which you can become involved. Most types of electroplating processes are not expensive to set up (in comparison with other types of business) and it is very profitable as well. The electroplating process is widely used in many industries such as jewellery, medical, electronics etc. An electroplating process is fully suitable for the professional coating of many sorts of small car parts, for decorators, craft workers and model makers’ as well as for many engineering, restorers, art and other projects.
First of all we have to acknowledge that in order to achieve experience and skills in this useful and exciting subject you will need to learn it and to get practice of course. This means that you need to be patient and, initially, spend some time on each new item, which you electroplate for the first time. Then you will start achieving excellent results very soon and also you will be able to use that experience in future projects. We would like to recommend you to keep notes each time for the job you do because it will help you later on. Thickness and quality of coating is a complex combination of electric current, voltage, temperature of solution, time of exposure, quality of chemicals, position of plating objects, distance between the object and an anode, your equipment and of your experience as well. Therefore, the more jobs you carry out, the more experience you will gain and you will find the quality improving and you will carry out each project much quicker. In electroplating it is important to understand that a lot of things depend on the material you are using, its form, size, quality, temperature, the solution used and the different times that different processes take. So, it is advisable to keep notes of all those things including the type of anode, the voltage, dimension between anode and cathode etc. Also many videos and other useful information is now available on the internet.
Three different types of electroplating process:
1. Tank plating process is the most popular and useful process that is suitable for all types of electroplating or electroforming processes. It produces a high quality surface of plating objects and allows you to plate many items at the same time. You can also clean or electro-polish the plating objects in a tank as well. Using this process you can plate many objects inside and outside as well. It is very quick (plating time is usually 30-60 seconds) but this process requires equipment such as a power supply (rectifiers), tanks, anodes, cathode turning stands, heating and agitation systems. This equipment is very useful because it allows you to do many additional processes such as electro cleaning, stripping, electro etching and electro polishing. Usually each process, including rinsing, requires one tank with a correct solution. For example: just deep plating objects in a cleaning tank first, then take it out and deep it in a rinsing tank with tap water and finally deep it in a tank with the plating solution. Switch ON your power supply (rectifier) and wait for few seconds (it depends of the process) and then you will find your item fully plated.
2. The Brush Plating process is widely used to plate fixed items like kitchen and bath taps, showers, tubes etc. It gives you a good quality of plated surface if you are experienced enough and if the object for this process has been prepared properly. The chemicals for this process are more expensive (if compared against tank plating chemicals) because they are more concentrated and you will able to plate only one object at a time. However for brush plating process you have to know that objects can be plated outside only. This process is fully suitable only for Gold, Silver, Nickel, Copper and Chrome plating. If you wish to plate your objects in other metal (like zinc, tin, bronze etc) then you will have no choice but to use a tank plating process to get a good quality of plating surface).
3. The Pen plating process can be used to plate very small details, or individual small parts on a large object. For example, you can plate the fingernails or eyebrows on a bronze statue in silver. Pen plating is suitable only for Copper, Gold, Rhodium and Silver plating process.
In simple terms all of these processes consist of allowing an electric current from a rectifier to flow through a solution between metallic or other conducting materials placed in the solution at the positive (anode) and negative (cathode) terminals of a direct current circuit. The current flow in the circuit results in the release of charged metal particles called "ions" into the solution. They pass from the positive terminal (anode). We refer to the object being plated as a "Cathode".
What we should have to start a tank electroplating process?
To answer on this question we need to clarify first four questions:
A. Which process we are going to use - gold plating, chrome plating etc. We need to know this in order to get the right rectifier with correct amperage/voltage options. And we have to decide there if we need an ‘Agitation” and “Heating” options for plating tanks, which chemicals we will need, type of anodes etc?
Useful points on electroplating stations (rectifiers):
* Cathode Rotating Stand (CRS) - helps you to get a better quality of surface of the object that you plating and helps you to save money (because of additional anodes) on solutions. Also it saves your time as plating process goes much quicker.
* Agitation Systems (Air or Mechanical) - widely used to stir a plating solution inside a bath. It saves your time and it requires less solution as usual.
* Heating system - allows you to get a high quality of surface (plating area) and saves your time on plating process. For example: if you try to plate copper ring in solution with room temperature - it may take several minutes but if you plate the ring in solution with temperature about 35-70 C - it will take about 30 seconds only.
* Stripping option - allows you to change the polarity (positive and negative) in your plating tank without hands - just turn the switch in correct position. Very safety and healthy option when you plate large quantity of objects (work with high level of amperage).
B. How many items we want to plate at the same time? We need to know this in order to get the correct sized plating tank and anodes.
C. What is a maximum size of items we intend to plate? We need to know this to ensure that we have a correct sized plating tank, anodes and if we have a powerful enough power supply (rectifier).
D. Are we going to plate old or new objects? If we going to plate an old object we need to choose a rectifier with stripping option because it takes off the old surface first for the re-plating process.
Below is an example of the equipment and accessories required to plate a copper ring in 22 Ct Gold:
a) The power supply (rectifier) with 3 tanks for electro cleaning, rinsing and plating processes. As we mentioned before there should be an agitation and heating options in the plating tank for a best result.
(If you plan to re-plate old objects - you will need one more tank for electro stripping process and a rectifier (electroplating station) with a "stripping" option).
b) Gold plating/stripping anode.
c) Chemicals to make up the cleaning, stripping and plating solutions.
How to choose amperage of power supply (rectifier):
Most beginners are incorrectly trying to choose the correct amperage of power supply (rectifier) for their work from the size of plating tank. It is not the correct way as you will order much more powerful machine than you will required in reality. There is just one correct way for this purpose - to choose the correct power supply (rectifier) from the area of all plating objects that you are going to place in a plating tank at the same time. For example if you have a tank 250 x 250 x 250 mm (10 x 10 x 10 inch) for gold plating process (that require minimum amperage just 1 A per sq.inch) you will require a rectifier that will supply you amperage of 100 A, but in reality, if you place in the tank just a few objects with total plating area of 5 sq.inch then you will require a rectifier just on 5 A. No matter - how big your tank is: important is only a plating area. Unfortunately we cannot use car batteries or other non-regulated power supplies and adaptors if we want to achieve a good quality of surface. We must have a facility to regulate the voltage/amperage depending on the type of plating process (Gold, Chrome, Nickel etc), the type of object needs to be plated (round, square etc), their sizes and other factors such as the type of chemicals, quantity of objects, temperature of solution etc.
How to choose an anode for your work:
It depends on the material, size and the shape of the item that needs to be plated. These three things determine the anode and solution that you will require. The anode is the positive (‘+’) electrode, which is placed in the tank opposite the object that you are going to plate (cathode) which is a negative (‘-‘) electrode. Anodes should perfectly suit the item being plated so they must be chosen accordingly.
The most popular types of anodes for most popular processes are:
1. Copper anode for the copper plating process.
2. Gold or 316+ stainless steel anode for the gold plating process.
3. Silver or 316+ stainless steel anode for the silver plating process.
4. Nickel anode for the nickel plating process.
5. Brass anode for brass plating process.
6. Rhodium (or rhodium plating) anode for the rhodium plating process.
7. Peroxide Lead Anode for a chrome plating process.
It’s also necessary to choose the correct size of anode. It should be approximately twice bigger then size of a cathodes (plating objects) and anodes should be placed on two sides of the tank or (better, if you do not use a cathode rotating stands) on all four sides. Also, if your item is not flat, then it may be necessary to shape the anode to suit the form of the object being plated. Again: if you have a CRS (Cathode Rotating Stand) in your tank - you do not need any special anodes or anodes in big quantity as the CRS allows you to plate any object in a high quality with one flat anode only. It will also help you to make your work much quicker and it will save your solutions that you plane to use for this process. Please find any type and size of the CRS you may require in our Internet-shop ("Accessories").
In the end... there are 3 vital things that guarantees the success of the process that you are doing:
The plating process is only possible with the correct anode.
Size of anode MUST BE twice bigger than an area of objects that you are going to plate.
We may required a CRS, heating or/and an agitation system in a plating tank to get a good result.
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