Henkel’s portfolio of products for the hot dip galvanising (HDG) market now includes a number of new-to-the-UK surface solutions for many stages of the process, including acid/alkaline cleaning, pickling and pickling inhibitors, passivating or conversion coating prior to painting.
Cleaning is the vital first stage in any HDG process. For acid-based cleaning, which typically take place at temperatures up to 45°C, Henkel now offers BONDERITE C-IC HDG 21 Plus, a high-efficiency, low consumption, mono-component cleaner that offers easy management for users.
Similarly, for alkaline-based cleaning, which takes place at temperatures of between 45 and 80°C, BONDERITE C-AK 4181L is a high efficiency cleaner that has the capability to accelerate the subsequent pickling stage. Again a single part product offering easy management, C-AK 4181L can remove rust, paints, greases and carbon residues from ferrous and chrome nickel alloys, as well as titanium, when used as directed.
After cleaning and rinsing, pickling and inhibitors form the next phase of most HDG processes. Although acids are used typically to remove oxide in the HDG process, these attack base materials and cause metal loss and reduced strength. The solution lies in the use of inhibitors, which not only reduce metal loss, but acid consumption and hydrogen development (bubbles during pickling), thus offering extended bath life. In short, inhibitors reduce attacks and impede embrittlement caused by the absorption of hydrogen. The most recent development in this area is the introduction of BONDERITE S-AD 60500, a high concentration product suitable for use in baths up to 80°C. This advanced inhibitor is formulated specially to deliver cost-saving dependability, without slowing production.
With regard to pickling bath additives, Henkel can now offer the easy-to-use BONDERITE C-AD N, which reduces and controls fume emissions from tanks by up to 80%. The upshot is a healthier environment for workers and less structure corrosion.
Following another rinse stage, material then enters the flux tank, which prepares the surface for HDG deposition and protects against flash rust and thermal shock. Products such as BONDERITE C-AD HDG 35 provide benefits that include a reduction in salts consumption, homogenous deposition of salts, pH stabilisation and homogenous Zn deposition/consumption.
After galvanising and mechanical cleaning, the final stage in most HDG processes is passivation or conversion coating, which protects the HDG coating against corrosion. Here, BONDERITE M-NT 5992 is free of both Chrome-VI and organic compounds, and offers the potential to be used as a conversion coating of the formed layer. Furthermore, the product has a wide working temperature range (up to 45°C) and offers low consumption thanks to a proportionally small working concentration – all with better performance than Chrome-VI passivation.
All of these BONDERITE HDG products from Henkel have been proven at installations across Europe. For instance, the introduction of BONDERITE C-IC HDG 21 Plus cleaner at one particular plant led to a host of benefits, including very low consumption rates of around 1kg per 1000kg of material processed. In addition, the customer enjoyed further cost reductions due to lower inventory levels on chemicals and automatic dosing, while sludge levels were also reduced.
Elsewhere in Europe, a customer needed to export 70 tonnes of galvanised material to South America by sea, with a requirement for no white marks upon arrival. By adopting BONDERITE M-NT 5992 passivation/conversion coating, not only was this requirement met, but tank life was extended to in excess of one year.
Ultimately, the BONDERITE range of HDG products from Henkel is designed to enhance product performance, increase reliability, improve the overall manufacturing process and reduce costs – as increasing numbers of plants are discovering.