While the crucial practice of metal finishing is not new to the steel industry, the demand for faster, cheaper, sustainable and more resilient finishing is picking up speed and driving innovation. And as manufacturing grows and the market expands, producers are finding more need for a variety of metal finishing processes for their projects.
Metal finishing is the part of the manufacturing process that treats, coats or cleans the metal to improve its performance, corrosion resistance or aesthetics depending on what is required.
Polishing, grinding and brushing are the simplest forms of metal finishing and involve smoothing the surface of the meatal using abrasive materials. Blasting and vibratory finishing achieves a similar effect but uses more advanced methods.
Hot blackening and heat-treating both use high temperatures to create more durability in the metal. Heat treating hardens the metal whereas hot blackening deposits a layer of black oxide onto the metal to improve its abrasion resistance.
Powder coating and electroplating are generally the most advanced forms of metal finishing. Powder coating uses UV or heat curing to form a layer of plastic powder over the surface of the metal while electroplating uses chemicals and an electric current to adhere a thin layer of metal over the finished product.
3 Exciting Metal Finishing Innovations
Hydrophobic and Hydrophilic Pre-painted Metal
Pre-painted or coil-coated metal involves applying even layers of paint onto the metal before fabrication. This ensures a more even and durable finish. While this technique has been around since the mid-20th century, new technologies have made it more valuable by offering hydrophobic and hydrophilic coatings.
Hydrophobic pre-painted metal repels water, making it difficult for other materials to stick to its surface. This property enables quick and easy cleaning and is especially useful for businesses and public services that become targets of graffiti artists among other things.
Hydrophilic coil-coating, by contrast, attracts and retains water thereby reducing friction. This metal finishing technique is useful for applications such as protecting water pipes against corrosion by abrasives like salt and other minerals. Hydrophilic coil-coating has also become a popular coating for medical devices to minimise the risk of tissue damage.
New technologies have enabled nano-scale coatings which are between 1 and 100 nanometres thick which is microscopic in comparison to a human hair which is 80,000 to 100,000 nanometres wide. This minuscule scale gives manufacturers more control over metal properties while providing desirable qualities with minimal mass increases.
A valuable application of nanotech metal finishing is improving durability. In the car manufacturing industry, for example, repairing a scratched surface can cost a lot of money. While traditional scratch-resistant finishes can affect the material thickness or the final paint colour, nano-coatings are able to make car surfaces more resistant to abrasion without compromising these qualities.
Nanotech coatings can also make metals hydrophobic or hydrophilic, improve the electrical conductivity and in some cases, even make them anti-microbial. The possibilities for nanotech coatings are endless as nanoscience continues to advance.
Traditional electroplating methods are often energy-intensive and far from environmentally friendly as the improper use and disposal of toxic solvents can cause havoc in the soil and groundwater. The good news is that recent innovations are changing this and making electroplating a more sustainable practice.
One method of green electroplating involves dissolving aluminium in water instead of solvents. Aluminium is less harmful to the environment than chrome and cadmium and the use of water removes the risk of chemical leaks. Greenhouse gas emissions are also reduced as this process doesn’t require energy-intensive machinery.
Other growing methods of electroplating avoid wet surface finishing entirely and completely cut potentially harmful solvents out of the equation. This dry process also minimises industrial waste, making it even kinder to the environment.