Henkel Adhesive Technologies has sharpened the market fit of its Bonderite L-FM FL portfolio of polymeric coatings for the surface conversion of metals used in cold forming operations. The optimised Bonderite L-FM FL process reduces the number of treatment steps from as much as ten to one or two and is fast emerging as an attractive alternative in the production of high-performance automotive bolts and screws.
Medium carbon or alloy steel grades designed for cold formed threaded fasteners in property classes such as 8.8, 9.8, 10.9 and 12.9 generally require a prior surface conversion process to create a thin, adherent coating that will facilitate deformation and ensure the high-quality of the final products. In the automotive industry, these cold formed screws and bolts are used in a wide range of engine, powertrain, suspension, wells and other demanding applications.
Traditional zinc phosphating and reactive soap processes, although well established in metal pretreatment for cold deformation, are associated with a number of potential drawbacks, including high acidity as well as high energy consumption and phosphate sludge. Moreover, they can involve up to ten individual steps, from initial degreasing and pickling to activation, phosphating and soaping with frequent intermediate rinsing.
“With Bonderite L-FM FL, Henkel has developed an innovative solution to all of these challenges, which provides a flexible one-step process with superior cost performances, reduced CO₂ impact and a much smaller water footprint,” says Emilio Bucci, Henkel’s business development manager for Cold Forming in Europe.
Bonderite L-FM FL is a non-reactive, water-based polymeric coating that enables a sustainable surface conversion process. Since the coating adheres to the surface physically without any reaction, the only evaporation produced in the subsequent drying step prior to cold deformation is aqueous. As a one-step process, Bonderite L-FM FL eliminates all rinsing steps, which saves water and has a reduced energy demand with appropriately lower CO₂ emissions. Furthermore, when the cold formed screws are dephosphatised for final heat treatment, the polymeric coating is easier to remove, which permits the use of a dephosphating cleaner in much lower concentration, resulting in less consumption.
In addition to these environmental benefits, the Bonderite L-FM FL technology is characterised by its greatly reduced complexity over zinc phosphating. As a single bath process, it minimises equipment footprint and maintenance. Raw material surface properties require initial sand blasting or pickling and neutralising, but the conversion cycle is essentially simplified to one single step and operates at a temperature between 40°C and 50°C, providing significant time and energy cost savings. Overall productivity is also enhanced by the high lubrication and pressure resistance of Bonderite L-FM FL in comparison with traditional zinc phosphating processes, which results in a longer lifespan and has been confirmed in numerous industrial scale applications, according to Henkel.
“With its proven cost advantages and sustainability, Bonderite L-FM FL is considered the single most efficient and responsible surface pretreatment process in metal cold forming and is fast emerging as the industry’s preferred technology, especially in the global market segment of demanding automotive bolts,” Bucci notes, adding: “The simplicity of the process also means that it can easily be integrated in-line as well as in batch production lines.”
To help cold forming manufacturers maximise the productivity of their Bonderite processes, Henkel recommends the use of its dedicated Lineguard Automatic Line Control system. Lineguard is available in modular hardware and software configurations that enable precise and efficient bath management up to fully automated pretreatment control. It features state-of-the-art PLC, sensor and HMI technology that is integrated by the company’s specialists to provide a total system solution tailored to each customer’s individual needs, including process data acquisition and comprehensive documentation.
Will joined Fastener + Fixing Magazine in 2007 and over the last 12 years has experienced every facet of the fastener sector – interviewing key figures within the industry and visiting leading companies and exhibitions around the globe. Will manages the content strategy across all platforms and is the guardian for the high editorial standards that the brand is renowned.
