Manufacturers apply several types of metal plating finishes on custom parts, and each has its unique uses. Some plating finish solely improves the product’s looks, while others signify performance and reliability, or strike a middle ground.
Metal plating finishes continue to be a critical process after fabrication and are still recognized as a cornerstone of contemporary production. They can be employed in almost any application. Different metal finishes are available for prototyping and production, but not all are ideal for use. So, it’s easy to confuse metal plating for metal coating, but this guide will help the reader understand the two terms. A plated finish can be chosen for many reasons and has multiple advantages.
This article provides information on the major metal plating finishes and techniques and useful advice on obtaining a high-quality finish.
What is Metal Plating Finish?
Metal Plating Finish
Metal plating finishes create a surface coating on components by using other metals such as chromium, copper, or nickel among others. The technique works to improve the aesthetic appearance as well as the non-corrosion properties of metals and other substances.
The plating finish brightens the irregular surface of the machined parts. It also enhances the appearance, decreases resistance, increases hardness, and paint adhesion and solderability.
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Metal Plating Finish Process
Metal plating is a process that comes in pretreatment, plating, and post-treatment cycles. Here’s an introduction to the most basic and general metal plating procedures.
Step 1: The pretreatment process typically cleans the substrate before it enters the plating phase. Washing and rinsing reduce unwanted particles on the material surface.
Step 2: The cleaning type needed is defined by the part of nature being cleaned. Some of the plating processes simply call for the removal of bulk contaminants, unlike others which are used for the removal of oils or grease.
Step 3: For electroplating, you require an anode, cathode, rectifier, tank, and a plating bath.
Step 4: Start the plating surface process by passing on the electrical current. If you need a thicker coat to be formed, you need to increase the exposure time. They are temperature, voltage, and immersion duration variables.
Step 5: For Post-treatment, use a cleaner after getting the required coating buildup on the parts. Electrolytic polishing can further improve corrosion protection in the finished parts.
Step 6: Metal plating usually results in hazardous waste products especially those which are heavy metals. Discharge plating wastewater only after it has been through some form of treatment to remove the impacts on the environment.
Different Types of Metal Plating Finishes
Industrial metal plating has many choices depending on the needs of the client. Here are key types of metal plating finishes used across industries:
Zinc Plating
Zinc Plating
Zinc plating is the cheapest form of galvanizing metal. Whether the application is accomplished through dipping or spraying, the molten zinc provides a strong and ductile layer for metal substrates. When electroplating, the metal behaves as a cathode, and the zinc acts as an anode in a zinc salt bath. These methods facilitate thickness control and provide perfect coverage for the substrate with the coating material.
Chrome Plating
Chrome Plating
Chrome plating, also known as chroming or alodine finish, employs chromium baths or chromic acid to create a hard surface-covering layer. It is recognized mainly for its function of enhancing material appearance but also offers increased hardness and effective corrosion protection. It is mostly used in metal works to re-establish worn components to their standard accuracy.
Nickel Plating
Nickel Plating
The electroless nickel plating is commonly used for its appearance and protective qualities, being the most popular technique. It gives wear or a hard surface appropriate for home-use products such as fixtures and cutleries. Nickel has a good affinity for aluminum and copper and its major use is as an undercoat for chrome plating to magnify the degree of beauty.
Copper Plating
Copper Plating
Copper plating is excellent for conductivity and relatively cheap – for the electronics industry, especially in printed circuits. Its high plating efficiency and low material cost are ideal for applications where electrical conductivity and heat dissipation are of essence for instance in sensitive electronic components.
Cadmium Plating
Cadmium Plating
Cadmium plating creates a ductile silver-coloured deposit which is suitable for components that need malleability like bolts and screws. It is highly resistant to corrosion as well as easily solderable. Hence ideal for high-stressed applications such as submarines and military hardware. The plating can also resist chemical reactions, making it optimum for widely corrosive conditions.
Silver Plating
Silver Plating
The process of silver plating offers a physical appearance and has the added benefit of being a good conductor of electric current. Soldered often in place of gold, it is an excellent electrical conductor and, thus adequate for electronics. Many design manufacturers employ silver plating to obtain the high conductivity and strength of copper parts at a reasonable cost.
Gold Plating
Gold Plating
Gold plating is well known for its ability to resist oxidation and conduct electricity. It efficiently redeems these valuable properties to other metals such as copper, and silver. Gold plating plays a critical role in electronic connector applications since conductivity and corrosion are critical to connector performance and durability.
Tin Plating
Tin Plating
Tin is a process of depositing a solderable layer of tin on the material surface using the electroplating process. Tin is relatively readily available and cheaper than some of the valuable metals such as gold or platinum. Tin plating is regularly used to improve the solderability and protect the components from oxidation in electronic components and connections.
Rhodium Metallization
Rhodium Metallization applies a thin layer of rhodium used in jewelry for shine to make a surface more reflective.
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Metal Plating Finishes for Custom Products
The following are industry-standard metal plating methods frequently used:
Electroplating
Electroplating
In Electroplating, a metallic layer is built on the workpiece surface. It typically uses an electric current in an electrolyte with dissolved metal ions. The latter are attracted to the negative ions of the workpiece and so form a shield around it. Electroplating is preferred to produce a uniform coating and modify the surface characteristics to produce a glossy, tough skin on each of the articles to be coated.
Electroless (Autocatalytic) Plating
Electroless plating
Electroless plating is an autocatalytic plating that doesn’t require electric current. Instead, it employs a chemical treatment that electroplates metals such as nickel or copper on the substrates. The process is comparatively cheap as it does not involve the use of complex machinery. Electroless plated components do not corrode over time and hence are suitable in oil and marine industries, where the component is likely to be used for decades.
Immersion Plating
Immersion plating occurs when a noble metal layer is placed on a base material by partially immersing it in a solution containing noble metal ions. The actual process is based on the inherent displacement reaction of the metals and yields a consistent and thin layer. This type of plating is most suitable for noble metals like platinum, silver, and gold due to their stability.
Carburizing
Carburization
Carburizing strengthens and hardens a workpiece’s surface while leaving its core soft. Also known as case hardening, the method entails adopting carbon into the surface layer to form a thick, thin shell. Carburizing is widely used to develop additional strength, help avoid rust, and improve the material’s abrasion resistance, especially in the usage of heavily loaded equipment.
Physical Vapor Deposition (PVD)
PVD Deposition
PVD deposition allows a thin layer to be coated on a substrate in a vacuum. The material in vapor deposits onto a surface through sputtering, ion plating, and vacuum evaporation. PVD is appreciated for its high adhesion rate and fast deposition, therefore widely used in the precision machining industry.
Plasma Spray Coating
Plasma Spray Coating
A coating technique in which a surface is coated with particles heated to a plasma spray coating. Usually, plasma sprays can be applied to ceramics, metals, or any composite material. This intensive method offers a tough, sealing shield to intensify the product’s heat, wear, and oxidation performance. The aerospace industry uses plasma coating to shield components from the environment to increase durability.
Limitations and Benefits of Metal Plating
Metal plating increases the surface characteristics of components, offering multiple advantages for various industries:
- Increases material beauty since there is an additional layer on the surface.
- A variety of metal plating finishes are available for different types of material.
- Shields parts of a system from wearing out and corroding.
- Relatively economical solution.
Despite its benefits, metal plating has some limitations:
- Plating must chip or crack under some conditions.
- Process may take time hence disrupting the production cycle.
Applications of Metal Plating Finishes
Metal plating finishes are used in many industries: Industrial and automotive Technology, Aerospace and Aviation, marine, automotive, construction, manufacturing, and many others. Here are some primary applications:
Aerospace
In aerospace, electroplating protects material surfaces being exposed to harsh conditions by offering a thin sacrificial layer that will corrode instead of the base material.
Automotive
Automakers employ metal plating for special pieces and use nickel and decorative chrome plating for car accessories and bike accessories. Black oxide coatings are applied primarily to machined parts to provide more reliability.
Dental and Medical
In the medical field, it enlarges and reinforces tools while also making them resistant to rusting. Gold plating, in addition, is applicable in dental inlays and so many ways to aid different procedures.
Jewelry
Electroplating makes jewelry pieces such as rings, pendants, and bracelets look more attractive and durable.
Key Considerations for Metal Plating Surface Finishes
To ensure metal plating finishes results, several key factors must be considered during the process:
Pre-Plating Material Condition
Materials to be plated should be in their best state before it is plated. Substances like heat treatment scales, oxide layers, or oil films can prevent proper plating. It is important to remove these from the component’s surface. These contaminants must be pretreated to guarantee good adherence to methods including; acid pickling, bead blasting, vapor blasting, use of deoxidizers, and alkaline presoaks.
Thickness Tolerance
Coating thickness also can be challenging for plating if the thickness of the coating is too large or too small. Setting up of right thickness parameter is essential to achieving repeatable outcomes.
Consider the following when determining thickness:
- In any case, when electroplating, you normally get a uniform layer, thus the tolerance issues may not be problematic.
- Identify workpiece areas that should be plated to a precise thickness; such as corners and areas in between intricate shapes.
- Electrolytic plating is often characterized by thicker deposits on flat surfaces, and thin deposits on recessed surfaces, so it may be difficult to meet very strict dimensional requirements for a specific shape.
- Thickness control must be checked regularly, and the best way is to set checkpoints where thickness control can be easily checked to conform with the required specifications.
Thread Inclusion
When threaded surfaces are the part being plated, there is an added thickness requirement for the plates, screws, and hydraulic fittings. Because plated threads tend to be about 4 times thicker than flat threads. The intended buildup should be integrated into the plating process so that the thread components achieve the necessary specifications to enable proper fitting.
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Custom Metal Products Plating Service Offered by ProLeanTech
For your metal plating projects, trust the professionals at ProLeanTech. They’ll help you get the best value for your money. In the industry for several years, ProLeanTech provides a wide range of metal plating services to increase the performance and reliability of your parts. Our services are affordable as we always strive to give you the best possible outcomes not solely to meet your needs but to ensure long-term collaboration. Contact us today and we will assist you begin your custom metal plating projects!
Final Summary
Metal plating finishes are crucial for the appearance of your products while increasing the products’ life span and decreasing their vulnerability to wear and corrosion. Knowing your specific requirements and the right type of plating will help you get the most out of your project.
FAQ
Q1. Does gold plating wear off?
Of course, gold plating can fade or turn black, and thus becomes not so shiny anymore. Vulnerability to wear and tear is expected irrespective of the quality of the component used.
Q2. Can rust be stopped with metal plating?
Yes, metal plating assists in preventing the formation of rust on the tools and other machinery to improve their performance. Since a layer is formed on the surface to minimize resistance effects.
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