CNC parts machining often involves surface treatment processes, one of which is more common during electroplating. The so-called electroplating is the process of plating a thin layer of other metals or alloys on the metal surface using the principle of electrolysis. The metal plating layer is plated on the substrate, and the purpose of electroplating is to modify the surface properties or dimensions of the substrate. In the process of CNC parts machining, what is the effect of the surface treatment skill of electroplating? In this article, we will focus on metal plating.
Metal Plating And Advantages
The electroplating process is a post-production process. It involves coating or covering the surface of the workpiece with a thin layer of metal. The basic understanding of electroplating is to plate a thin layer of metal on the substrate. Therefore, the goal is to improve the overall quality of the product. The many benefits of metal plating include:
- Improve corrosion resistance
- Material surface hardening
- Improve paint adhesion
- Improve solderability
- Improve the wear resistance of parts
- Reduce friction
- Change conductivity and conductivity
- Improve heat resistance
- Provide shielded radiation
Metal Coatings: Basic Principles
There are many steps in electroplating, and some considerable steps are required from pre-treatment to post-treatment.
Step 1: Pretreatment Of Metal Plating Surface
The first step of electroplating is to prepare the substrate. Therefore, you first need to pre-treat it to prepare the substrate for metal plating. This is an important process designed to remove all harmful contaminants, grease and oil. These materials may hinder the electroplating process and hinder satisfactory and uniform processing. Depending on your preferred plating or substrate, this step may include several sub-steps. The sub-steps can range from cleaning to ascent and other pre-treatments.
Once the proper finishing of the substrate is complete (if there are welds, burrs, and other surface inconsistencies), you can now clean the substrate. There are a variety of techniques that can be used to clean the surface of the substrate. It can operate with alkaline or acid chemicals.
The chemical cleaner you use depends on the type of material you use. For example,
Alkaline Cleaners:
These products contain chemicals such as carbonates, phosphates, and borax. They are more effective for electroplating surface cleaning of steel, copper, nickel, stainless steel, lead and titanium.
Acidic Cleaners:
They include hydrochloric acid, sulfuric acid and several others. It is recommended to use them to clean metals such as magnesium.
Inhibition Of Alkaline Cleaners:
These cleaners help overcome the problem of negative corrosive reactions to zinc, aluminum, brass, bronze, and tin.
In addition, you should be aware that some substrates only need to be cleaned once. Others may need two or more cleanings. After each treatment, thoroughly rinsing the substrate with distilled water will help remove all chemical cleaning agents.
Step 2: Determine The Effectiveness Of The Cleaning Process
The requirements of your part will determine the plating process. At the same time, it determines how clean your substrate should be. For example, some CAD electroplating techniques only need to remove dirt and large pieces of dirt.
On the other hand, others need to completely remove oil and grease. So how to check the cleanliness of the substrate?
Water Breaking Test.
After the final product is fully raised, hold the substrate and pay attention to how the water pours out of its body. If poured on a large piece of paper, there is no oily residue. However, if there are water droplets, oil and grease may still be present.
Wipe Test.
Here, use a clean cloth to wipe the surface of the substrate. If you find dirt or residue on the cloth, you may need to clean the substrate further.
Reflectivity.
The reflectivity of some products helps to easily measure their cleanliness.
Step 3: Set Up The Electroplating Station
Once a sufficient level of cleanliness is reached, the process can begin. First, you need a rectifier or other DC power supply. Remember, our focus is on electroplating. Other materials include tanks (or barrels), cathodes, anodes, and appropriate plating solutions.
The anode includes the solid metal sheet you want to deposit, and the cathode is your substrate. Most manufacturers use water as the plating solution. It is quite easy to set up a plating station. First, connect the negative lead of the rectifier to the substrate. Then, put the positive lead directly into the electroplating solution.
Step 4: Electroplating Process
Once the current is turned on, the deposition process begins. If you want to coat your products with thicker coatings, then you need to expose them to electric current for a longer period of time. Before electroplating, you need to consider some variables for different metals. These variables include voltage level, temperature, immersion time, etc.
In some cases, a plating solution may already be prepared. In this case, you will print the settings of each factor on the container. Generally, higher voltages tend to provide more suitable results. In this way, there will be no bubbles in the solution.
Step 5: Post-plating Process
Once proper deposition is achieved on the metal surface, post-treatment cleaning is usually required. This is important to suppress discoloration. There are several cleaners on the market. Electrolytic polishing after electroplating is also an effective technique. This helps to improve corrosion resistance.
Step 6: Waste Treatment
After many electroplating processes, heavy metals are usually produced. Due to their high levels of toxicity, these metals can be dangerous. Therefore, it becomes important to be fast and effective. It is an effective method to pre-treat electroplating wastewater before treating it.
Standard Electroplated Finishes Available For Industrial Grade
Zinc Plating
Zinc is one of the cheapest materials to provide galvanized coatings on metal substrates. The application of zinc is through molten bath dipping and spraying. The substrate is the cathode, and the metallic zinc is the anode in the soluble zinc salt electrolyzer. The galvanizing process produces a very ductile coating. For this kind of metal coating, it is easy to control the thickness and uniformity.
Chrome Plating
This electroplating process usually involves the use of chromic acid and a trivalent chromium bath to create a coating on the metal part. The main purpose of chrome plating is to improve the aesthetics of the material. However, the chromium metal coating also increases the corrosion resistance and hardness of the material. These chrome-plated parts are suitable for industrial applications. Sometimes, it also helps to restore the tolerances of worn parts.
Copper Plating
When your application requires cost-effectiveness and high conductivity, copper plating is the best choice. This procedure is usually used as the main coating pretreatment for subsequent electroplating surfaces. It is one of the most popular metal plating finishes for electronic components such as circuit boards. Because of its low material cost and high plating efficiency, it is a popular choice.
Nickel Plating
Another popular plating metal is nickel because it can be used for electroless plating. Nickel plating helps to coat household products such as tableware, showers, door handles, etc., to enhance aesthetics and wear resistance. This electroplating technique is most suitable for aluminum and copper. However, it is applicable to several other metals. It is also used for bottom plating of chromium.
Gold Plating
Gold is popular because of its high conductivity and oxidation resistance. A simple way to impart these important properties to silver and copper metals is gold plating. It has a wide range of applications in improving the conductivity of electronic parts such as electrical connectors.
Silver Plating
Similar to gold plating, silver plating also improves the beauty of related materials. When it comes to silver plating, conductivity also plays a role. Many manufacturers choose silver plating because it is cost-effective and cheaper than gold. It can also more fully electroplate parts made of copper.
There are many methods for different metal electroplating techniques to impart metal plating on metal parts. A smooth, fast and uniform coating is formed on the electroplated material. This effectively provides protection and decorative appearance to metal parts. Electroplating can also improve the physical, chemical and mechanical properties of parts, thereby affecting their behavior during processing.