Saffet Kalender, Director at AEON by Pitacs, discusses manufacturing processes to ensure you have all the facts when selecting a radiator for your customer.

The first consideration when manufacturing a premium heating product is choosing a high-quality material. Mild steel is a popular choice for radiators produced in bulk quantity for commercial and residential use, due to its low material and manufacturing costs, and its easy availability, which increasingly allows manufacturers to offer items with designer aesthetics at budget prices, finished in chrome plating or powder paint. However, mild steel products are very susceptible to corrosion, which also causes cracking and discolouration of any coatings applied and, once rusted, cannot be recycled. 

In contrast, a premium 304 grade stainless steel has a high nickel content, making it suitable for use in manufacturing sculptural designs in brushed matt or highly polished finishes. This material won’t suffer flaking or discolouration, as the very low carbon content alloy will not corrode even in very damp conditions. The surface can also be easily re-worked to bring it back to original condition if scratched, and the entire product can be recycled at the end of its usage.

The one area in which stainless steel underperforms mild steel is heat output. At 15.1W/mK, stainless has less thermal conductivity compared to mild steel (80.2W/mK). However, aluminium performs even better (250W/mK in this comparison). Aluminium radiators emit heat and respond to changes in water temperature quickly, giving the consumer greater control over their environment. 

As a non-corrosive, aluminium also avoids the pitfalls of rust discolouration and flaking and, furthermore, the material is lighter than steel, which can make installation requirements easier. Of course, both stainless steel and aluminium can increase costs significantly compared to budget materials.

The next consideration is how to achieve a uniform, precisely constructed product, even with the more intricate shapes and designs. When working in mild steel, traditional welding techniques will leave some evidence behind and negatively affect the aesthetics of the finished product. Laser or projection welding generally give better results, but drastically limit the range of application; in other words, the manufacturer is limited by the number of designs that can be produced in this way. 

At AEON, we employ a TIG (gas tungsten arc) welding process during the manufacture of our sculptural heating solutions. TIG welding allows the manufacturer to operate with a high degree of precision, and create completely seamless, almost invisible, joints that are as strong as the main body, even in stainless steel and aluminium, which typically are harder to work with. 

This process allows the welder a tighter control over distortion, which is particularly important in creating radiators with multiple uniform elements. While the TIG process creates beautiful results, it is slower than most other welding techniques, and requires a higher level of skill from the welder, which can impose a longer lead time. 

Thirdly, while consumers may seek the benefits of stainless steel or aluminium, for stylistic purposes they may not want the silvery colouring of a brushed or polished finish. A quality paint layer finish can offer a range of gloss, matt, metallic, and textured finishes, as well as the possibility to colour and texture match your radiator to other elements in your room design. If perfect matches are desired, ask your suppliers for RAL spot colour codes, so that you can be sure that items from different suppliers will cohere exactly. 

However, even a high-quality paint finish on stainless steel can be susceptible to cracking and wear. At AEON, we recommend opting for a physical vapour deposition (PVD) finish where these are available. PVD, which is also known as thin-film coating, is a specialist manufacturing technique where the coating is vaporised and deposited atom by atom onto the steel surface, forming a bonded, metal, or metal-ceramic surface layer. 

In order to achieve a PVD finish, the coating process has to take place in a vacuum with specialist tooling and equipment, which is understandably more expensive than applying paint layers, and therefore not as available to customisation of colour; the radiator manufacturer will predefine the finishes available, rather than offering an ‘any RAL’ choice to the consumer. However, the end result is a highly durable, beautifully even finish that functions as part of the radiator itself; it will not tarnish, chip or corrode, just as the original stainless steel would endure. 

In achieving this aesthetic versatility, aluminium can also deliver well; AEON’s own aluminium ranges all feature an anodised finish in a palette of metallic tones.

Anodisation is an electrochemical manufacturing process, that converts the surface layer of the aluminium into an anodic oxide, by passing an electrical charge through the material while it is immersed in an acid electrolyte bath. This layer is porous, allowing for colours and sealants to be applied afterwards, while still maintaining a surface that is durable and highly resistant to corrosion. 

Similar to PVD coating, the manufacturing process is more time-consuming, costly, and requires more skill than painting, but the end result offers a far superior finish, both in terms of aesthetic and practical use.