Electroplating: Surface treatments by electroplating
Whether corrosion protection for steel components, wear resistance for pressure cylinders or conductivity for connectors, electroplating is one of the most versatile and economical methods of surface finishing in modern manufacturing. This article provides the specialist knowledge required for purchasing decisions, discussions with suppliers and design engineering.
What is electroplating?
Electroplating is also known as electroforming or electroplating. It is an electrochemical process in which a metallic coating is specifically deposited on metallic surfaces. It is based on controlled electrolysis. An electric current is passed through a galvanic bath containing the ions of the coating metal.
The workpiece to be coated forms the cathode (negative pole), while an anode made of the coating metal forms the positive pole. In the electric field, positively charged metal ions migrate to the cathode and are deposited there as a uniform coating. Depending on the electroplating process, coating thicknesses of a few micrometres to several tenths of a millimetre can be achieved.
The metallic coatings produced specifically influence the following properties of the base material:
- Corrosion protection: Protection against attack by moisture, salts and chemicals
- Wear resistance: Increased hardness on the surface and reduction of friction wear
- Conductivity: Improvement of contact resistance and transmission quality
- Mechanical properties: Increased tensile strength due to metallic sheath around the base body
- Look and feel: Decorative surfaces, gloss, color (gold, chrome, copper)
- Solderability: Improved connections in electronics
Galvanization vs. electroplating?
Both processes are based on electrolysis - but the aim and result are fundamentally different. In industrial procurement, clear differentiation is crucial. This allows you to select the right process and avoid misunderstandings with suppliers.
| Features | Galvanization | Galvanoplastics |
| Goal | Coating of an existing component | Production of a new metal part |
| Substrate | Remains in the end product | Removed after the process |
| Layer thickness | 1-50 µm (functional to decorative) | 100 µm to several mm |
| Typical application | Corrosion protection, wear protection | Molded parts, replicas, electronics |
| Economic efficiency | High quantities efficiently | Flexible, even for individual pieces |
Decision support: If you want to give an existing component specific properties (corrosion protection, conductivity, hardness), electroplating is the right choice. If you want to reproduce a filigree metal part without machining - e.g. molds, reflectors or record matrices - electroplating is the right process.
Galvanic processes
Electroplating technology comprises different variants that vary according to the metal, system concept and intended use.
Electroplating processes according to system type
- Rack electroplating: Workpieces are mounted on racks and guided through the process chain. Ideal for large, sensitive or geometrically complex components. Higher set-up costs, but precise control over coating thickness and quality.
- Barrel electroplating: Bulk parts (screws, nuts, small parts) are electroplated in rotating drums. Very economical for high quantities, but with less uniform coating thickness across the component.
- Strip electroplating: Continuous coating of metal strips or wire. Standard for contact strips and connectors in electronics.
- Brush plating (brush electroplating): Local coating without immersion bath. Used for repairs, on-site maintenance of large components or selective coating.
Functional vs. decorative electroplating
Functional electroplating technology The aim is to achieve technical properties: corrosion protection by galvanizing steel components, hard chrome plating of pressure cylinders or nickel as a barrier layer. The coating thickness is typically 5-50 µm, with hard chrome plating up to 500 µm.
Decorative electroplating prioritizes look and feel. Typical applications: Chrome plating of bathroom fittings, gold plating of jewelry and furnishing elements, copper plating for a vintage look. Layer thicknesses here are often in the 0.1-5 µm range.
Related surface technology processes
In addition to classic electroplating, other processes are offered in practice by the same companies:
- Anodizing or anodizing electrochemically converts the surface of aluminum into a protective oxide layer.
- Sheet metal is mostly used for Hard anodizing The same is done with a thicker layer for components subject to heavy loads.
- Black finishing uses chemical processes to produce a black oxide layer on steel, primarily for optical reasons.
- Passivating strengthens the natural protective layer of stainless steel by chemical cleaning without applying a new layer.
- Phosphate conversion coating finally serves as a primer before painting or oiling.
Materials in electroplating
The choice of base material is the key decision in electroplating. It determines properties, costs, environmental relevance and legal requirements.
| Metal | Main property | Typical application |
|---|---|---|
| Zinc | Corrosion protection (cathodic protection) | Steel components, screws, body parts |
| Nickel | Hardness, wear resistance, corrosion protection | Tools, electronics, automotive parts |
| Chrome (hard) | Extremely high hardness (1,000-1,100 HV) | Hydraulic cylinders, pressure rollers, molds |
| Chrome (decoration) | Gloss, aesthetics | Sanitary, design elements |
| Copper | Electrical conductivity, adhesive primer | Printed circuit boards, pre-treatment layer |
| Gold | Contact reliability, conductivity, corrosion resistance | Connectors, microcontacts |
| silver | Highest conductivity, reflection | High-frequency technology, contacts |
| Tin | Solderability, food safety | Electronic components, tin cans |
| Zinc-nickel | Improved corrosion protection, RoHS-compliant | Aerospace, Automotive |
Substrates and pre-treatment
In principle, all electrically conductive materials are suitable as substrates. Steel, copper, brass and aluminum are the most common base materials. Plastics can be made electroplatable through conductive coating (electroless copper or nickel pre-plating). This is relevant for lightweight construction in automotive and electronics.
A clean, oxide-free surface is a basic prerequisite for an adhesive thin layer. Typical preparation steps: degreasing (alkaline or electrolytic), pickling (acid), activation. Errors in pre-treatment lead to coating defects such as bubbles, delamination or uneven coating thickness.
Galvanizing: Advantages and disadvantages
| ✓ Advantages | ✗ Limitations & risks |
|---|---|
| Significant extension of component service life | Complex process chain (pre-/post-treatment required) |
| Precisely adjustable layer thicknesses (µm range) | Environmental regulations (chromium VI, waste water disposal) |
| Combination of several metals possible (multilayer) | Poor layer thickness distribution for internal geometries |
| Almost any component geometry can be coated | Hydrogen embrittlement possible with high-strength steels |
| High process repeatability for series production | High investment costs for own electroplating plant |
| Economical for high quantities | Quality assurance requires specialist know-how |
| Improvement of electrical and thermal properties | Chromium VI restrictions due to REACH regulation |
Important regulatory information for purchasers
REACH Regulation (EU): Hexavalent chromium (chromium VI) has been subject to authorization in the EU since 2017 (SVHC). Many companies have switched to chromium III or zinc-nickel. Check conformity during procurement and actively ask suppliers about the chromium system used.
RoHS Directive: Cadmium coatings (formerly standard in the aerospace industry) are prohibited for most applications. Alternative: Zinc-nickel alloys.
Hydrogen absorption in high-strength steels: Steels with a strength of over 1,000 MPa can absorb hydrogen in the galvanic process. Heat treatment for de-embrittlement (at least 4 hours at 190-220 °C, in accordance with DIN EN ISO 4042) must be specified.
Galvanizing: Applications
Electroplating technology is used in almost every manufacturing sector.
- Mechanical engineering & printing technology: Hard chrome plating is the standard for pressure cylinders, piston rods, rollers and guide rails. Coating thicknesses of 20-500 µm significantly increase the service life of these wear parts. Alternatively, nickel composite coatings (e.g. nickel-SiC) are becoming increasingly important for extreme abrasive wear.
- Automotive: Electrolytically galvanized steel (EG steel) is the basic material for bodywork and chassis. Zinc-nickel coatings are increasingly replacing pure zinc and offer significantly better resistance to corrosion (≥ 720 hours salt spray test in accordance with DIN EN ISO 9227).
- Aerospace: Highest demands on coating quality and verification. Cadmium-free coatings (zinc-nickel, IVD aluminum) are standard. All electroplating processes must be qualified and audited in accordance with aerospace standards (AMS, NADCAP).
- Electronics & electrical engineering: Gold contacts on connectors, tin coatings for solderability, copper on printed circuit boards - electroplating is indispensable in electronics. Strip electroplating enables highly efficient inline coating with tight tolerances (layer thickness ± 0.1 µm).
- Medical technology: Implants, surgical instruments and imaging devices benefit from electroplating. Nickel- and chromium-free coatings (titanium, gold, PTFE dispersion layers) are prescribed for implants. Compatibility with the human body in accordance with ISO 10993 must be proven.
- Energy & e-mobility: Electroplated copper layers on current collectors play an important role in the production of battery cells. Bipolar plates coated with nickel are used for fuel cells.
Electroplating technology at FACTUREE
As a digital procurement platform for drawing parts, FACTUREE offers access to a qualified network of electroplating and surface treatment companies - from the coating of individual components to series production.
Whether galvanizing steel, anodizing aluminium, nickel-plating or galvanizing components: at FACTUREE, we find specific partners with the right process, the right certification and free capacity.
Metals such as copper or nickel, silver or gold, zinc or zinc-nickel alloys are covered, as are special coatings for special requirements in the automotive, aerospace and medical technology sectors.
Your advantages with procurement via FACTUREE: Qualified network of certified electroplating companies (DIN EN ISO 9001, NADCAP, etc.) Quick quotations for standard and special coatings | Transparent specific requirements directly in the inquiry Support with the selection of standards (DIN EN ISO 4042, DIN 50961 etc.) Flexibility with quantities: Prototype to large series
