Nickel plating can improve your product’s durability, hardness, conductivity, and heat resistance while preserving it from corrosion and improving its aesthetic appeal. However, before you hire a metal finisher to plate your parts, you must choose between two plating methods: electrolytic and electroless plating.
Both procedures are explained in the following guide, along with how they differ and their respective advantages.
What Is the Difference Between Electrolytic and Electroless Nickel Plating?
Traditional electrolytic nickel plating uses a catalyst and a direct current (DC) charge to initiate a chemical chain reaction that coats an object (the substrate) with a thin nickel layer. Electroless nickel plating, on the other hand, requires neither a catalyst nor a charge. On the other hand, Electroless recipes comprise a chemical reducing agent (phosphorous) that allows the user to coat the substrate without any additional processing.
Both processes deposit a thin layer of nickel on the target surface. Still, electroless nickel plating (ENP) outperforms electrolytic nickel plating in wear and corrosion resistance, lubricity, and other performance attributes. In addition, ENP, also known as autocatalytic coating, is easy to apply in uniform layers and can be employed on projects with tight tolerance criteria.
On the other hand, electrolytic plating is often thicker around the substrate’s corners and edges and cannot achieve the same level of precision. Deposit density is controlled during electrolytic plating by the length of time the product is submerged, and the number of amps per square foot applied. Nickel plating is a method of applying nickel to metals.
Before plating, the substrate material must first be cleaned and prepared. Pretreatments differ based on the substrate and the intended use of the result.
The item is then immersed in a plating bath containing positively charged, dissolved nickel-phosphorus. The positively charged nickel ions are drawn onto the substrate’s surface by the substrate itself, resulting in a fine layer of coating. Electroless nickel plating does not require electricity or ongoing filtering to prevent particles from adhering to the surface.
Electroless Nickel Plating is used in the following industries.
- Capital equipment for petrochemicals
- Handling of paper and corrugated materials
- Tooling security (plastic injection ductile iron stamping)
Electroless Nickel Plating’s Benefits
Electroless nickel plating has several advantages versus electrolytic nickel plating, including the following:
More Consistent Deposits Thickness: With tolerances of +/-.0001 inches, electroless plating is more exact than electrolytic plating. It can build intricate shapes and eliminate the “dog bone effect,” which occurs when electrolytic plating is performed with too many amps per square foot, resulting in an uneven deposit.
Superior Corrosion Resistance: Due to the addition of phosphorus to the solution, ENP has higher corrosion resistance.
Phosphorus also has magnetic qualities that allow metal finishers to control the electromagnetic interference around the substrate. This property is essential in electronic applications.
Additional Hardness and Durability: ENP deposits can be heated to achieve a hardness of roughly 90% of chromium. As-plated, low-phosphorus ENP coatings have a Rockwell scale (Rc) of up to 63. ON THE OTHER HAND, type II brilliant nickel deposits formed by electrolytic plating have an as-plated hardness of 50+ Rc.
Improved Lubricity: Electroless nickel plating reduces friction between materials, resulting in improved lubricity and less surface scarring.
ENP is more ductile than typical nickel coatings, which means it’s less likely to crack, break, or shatter under stress. ON THE OTHER HAND, type I pure nickel has equivalent ductility and can meet or surpass SAE International’s AMS2424 requirements.
Greater Coating Versatility: Electroless nickel plating can be applied to almost any metallic substrate, and the thickness of the coating is unrestricted.
ENP is also an excellent option for materials that will be salvaged in the future.
Process of Electrolytic Plating
Electrolytic plating, like electroless nickel plating, starts with cleaning and pretreatment of the substrate. The item is then immersed in a bath containing a conductive base and positively charged nickel. After the object has been submerged, the solution is given an external electrical current or rectifier. Next, the nickel anodes are charged by electricity, which causes them to release ions that adhere to the substrate’s surface, completing the plating process.
Electrolytic Plating’s Benefits
Electrolytic plating, rather than electroless nickel plating, is more appropriate in some cases. Here are some of the advantages of electrolytic plating:
Material Purity: Electrolytic nickel plating can be created entirely of nickel, whereas electroless nickel plating requires the addition of phosphorus. Other metal materials, such as copper, can be used in the plating process.
Electrolytic plating is often less expensive than electroless nickel plating, and it can produce higher production quantities with quicker turnaround times, making the process slightly more productive.
Enhanced Conductivity: When compared to electroless nickel plating, a higher nickel content provides improved conductivity.
Improved Heat Resistance: Nickel deposits can tolerate temperatures of up to 1,832°F after processing.
How to Find a Good Electroless & Electrolytic Nickel Plating Partner
When selecting a new manufacturing partner, make sure to thoroughly investigate them to guarantee you get the service and quality you need. The following are some questions to ask a potential metal finisher:
- What types of substrates can you process or plate?
- What kind of tooling strategy are you aiming for?
- What best practices does your company use to encourage employee loyalty?
- Do you have a track record of following best practices in chemistry and bath control?
- Are you able to meet the baking requirements for hydrogen embrittlement?
- Are the chemicals coming from a chemistry product source that is certified?
- What measures are in place for post-process inspection to assure thickness, adhesion, and conformity to specifications?
Smart Microns has the proven expertise to meet or exceed your metal finishing and plating needs, with over 75 years of experience. On our website, you may learn more about our electroless nickel plating and electrolytic plating services, or you can contact us right now to discuss your specifications.