Manufacturing Technology

Atotech tells us its silver zinc flake base coats eliminate the need for a second coat without compromising on performance.

The demand for economic and reliable finishing products is on the rise, especially in the fastener coating industry. The same can be said about the growing need for corrosion protection systems. 

Markets with corrosion performance requirements of up to 720 hours in Neutral Salt Spray Test (NSST according ISO 9227 or ASTM B117) are calling for simplified production processes. Atotech’s silver zinc flake base coat product line, Zintek® ONE, aims to exceed those requirements with only a single application layer. 

Zintek ONE is designed for medium corrosion protection of 480 hours NSST without base metal corrosion and Zintek ONE HP gives the unique performance of 720 hours NSST – all achieved with only one zinc flake layer. Performance is dependent on part geometry, substrate and application method.

Both products are designed to help reduce process costs, handling costs, energy consumption, and coating line occupancy, by removing the need for a second coating step – commonly required for standard zinc flake systems to achieve reliable corrosion protection. This makes the Zintek ONE coatings cost-effective alternatives to multi-layer zinc flake applications, hot dip galvanising and electroplated corrosion protection finishes.

The base coats are applied in a single dip-spin coating step that achieves a typical layer thickness of 6μm – 8μm. This is comparable to the total thickness of common two layer zinc flake coatings. Offering a uniform surface even after mechanical stress, the Zintek ONE product line is well suited for bolts, screws, springs and other parts with standard geometries – used in construction, automotive and heavy industry applications. 

“Successful trials in Germany, Italy, Asia and the USA have raised great interest for Atotech’s one coat system,” says Neil Patton, Atotech business manager, zinc flake coatings. “This is due to numerous coating benefits, including improved throughput capacities, which result in less handling thus reducing potential damage to the customer’s parts in a bulk processing system at the applicator base.” 

Neil adds: “The attractive aesthetics provide a uniform silver appearance combined with outstanding corrosion protection making Zintek ONE, as a single layer system, very appealing to coating companies, parts manufacturers and OEMs alike.” 

“With Zintek ONE’s optimised flow characteristics customers achieve uniform coating thickness distribution,” says Dr Volker Krenzel, Atotech technical manager, zinc flake coatings. “Touch marks can be minimised and the layer thickness distribution made more homogenous, which in turn leads to more reliable and reproducible corrosion protection capabilities.”

Utilising various top coats together with the one coat systems from Atotech enables coaters to individually adapt the process to various OEM requirements (i.e. chemical resistance and enhanced UV stability) while meeting the industry’s coefficient of friction demands and all the while providing superior corrosion protection. Since the zinc flake technology presents no risk of hydrogen embrittlement, the coating is ideal for high-tensile fasteners (Class 10.9 and higher). In-line with Atotech’s approach of providing environmentally friendlier solutions, its zinc flake coatings are also free of Pb, Hg, Cd, Ni, Co, and Cr(VI), and can be cured at moderate temperatures – eliminating concerns over annealing of high strength steel components. 

www.atotech.com