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Surface treatment of CNC machining precision parts: basic principles

Still on the basis, let's discuss the basic principles of the electroplating process. There are many steps in electroplating, and some fairly large steps are required from pre-processing to post-processing. There are several plating techniques you need to know, which we'll cover in this guide. However, in this section, we will focus on the basic procedure of the most popular electroplating process, which is electroplating.

Step 1: Metal Plating Surface Preparation

The first step in electroplating is to prepare the substrate. Therefore, you first need to pretreat 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 prevent satisfactory and uniform processing. Depending on your preferred plating or substrate, this step may include several sub-steps. Substeps can range from cleaning to rising and other pre-processing.

Once the substrate is properly finished (if there are welds, burrs, and other surface inconsistencies), you can now clean the substrate. There are various techniques available for cleaning substrate surfaces, it can be run through alkaline or acidic chemicals.

The chemical cleaner you use depends on the type of material you use. E.g,

Alkaline cleaners: These products contain chemicals such as carbonates, phosphates, and borax. They are better at galvanized surface cleaning of steel, copper, nickel, stainless steel, lead and titanium.

Acidic cleaners: These include hydrochloric acid, sulfuric acid, and several others. They are recommended for cleaning metals such as magnesium.

Suppressing Alkaline Cleaners: These cleaners help overcome problems with negative corrosive reactions to zinc, aluminum, brass, bronze and tin.

Also, you should be aware that some substrates only require one cleaning, others may require two or more cleanings. Thoroughly rinsing the substrate with distilled water after each treatment will help remove all chemical cleaners.

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 require the removal of dirt and large pieces of dirt.

Others, on the other hand, require complete removal of oil and grease. So how do you check the cleanliness of the substrate?

Water breaking test. Once the final product is fully raised, hold the substrate and notice how the water pours off its body. If poured onto a large sheet of paper, there is no oily residue. However, if there are beads of water, oil and grease may still be present.

Wipe test. Here, wipe the surface of the substrate with a clean cloth. If you notice 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: Setting Up the Plating Station

Once an adequate level of cleanliness has been achieved, you can now begin the process, which is explained along with the assembly of the station. First, you need a rectifier or other DC power source. Remember that our focus is electroplating, other materials include tanks (or barrels), cathodes, anodes, and appropriate plating baths.

The anode consists of the solid metal sheet you are depositing, and the cathode is your substrate. Most manufacturers use water as the plating solution. Setting up a plating station is fairly easy. First, attach the negative lead of the rectifier to the substrate, then, place the positive lead directly into the plating solution.

Step 4: Plating Process

Once the current is turned on, the deposition process begins. If you want your products to have thicker plating, you'll need to expose them to the current longer. Before electroplating, for different metals, you need to consider some variables, 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 for each factor on the container. In general, higher voltages tend to provide more suitable results so that there are no air bubbles in the solution.

Step 5: Post-Treatment Process

Once proper deposition has been achieved on the metal surface, post-processing cleaning is usually required. This is important to inhibit discoloration, and there are several cleaners on the market. Electrolytic polishing after plating is also an effective technique, which helps improve corrosion resistance.

Step 6: Waste Disposal

Heavy metals are often produced after multiple electroplating processes, which can be dangerous due to their high toxicity levels. Therefore, it becomes important to process quickly and efficiently. Pretreatment of electroplating wastewater is an effective method.