Coating Catch-Up

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TOOLING Coating catch-up

Selecting the right cutting tool coating can increase tool life, decrease cycle time and promote enhanced surface finish. Steed Webzell catches up with the ate of the art

here are continual coating multi-layer composition of the HCF be next to benefit from PVD coatings. Tdevelopments, with all of the major coating delivers a high elasticity that has WNT is part of the Ceratizit cutting tool manufacturers keen to the effect of damping cutting forces. consortium, which itself is recognised as launch coated tools that offer new Within the same family of inserts, a pioneer in coating, a recent case in advantages. For example, Horn’s in- WNT has introduced its HCF 3110 grade point being HyperCoat technology, house developed TH35 titanium which, while visually the same as HCF which features a particular resistance to aluminium nitride coating has been 1130, has been developed specifically for heat and a low tendency to stick. developed specifically to combat the machining cast iron. The combination of HyperCoat combines optimised carbide problem of built-up edge. This is the friction-reducing and multi-layer substrates with multi-layer CVD coatings potentially a major problem in sub- attributes of the coating combined with and an innovative final surface miniature machining applications such a K10 carbide substrate provides a treatment to improve the surface as those for which the company’s competitive alternative to ceramics. properties, cutting edge protection and Supermini boring and internal profiling “The move to PVD coating wear resistance of the insert. tools are designed. TH35 provides high technology in the production of cutting hardness and oxidation resistance inserts has resulted in edges that are NANO LAYERS combined with an exceptionally smooth much ‘sharper’ than can be achieved According to Sumitomo Electric surface. Another recently introduced with CVD,” says Adrian Fitts, WNT (UK)’s Hardmetal, today more than 80 per cent coating, WNT’s HCF 1130, comes into its business development manager. “This is of turning operations and 50 per cent of own when turning high tensile steels, ideal for applications in stainless and milling applications are performed with HSS materials and chrome-nickel steels. high alloy steels.” WNT says it will coated carbide, cermet and CBN tools. WNT says that this new coating can continue to introduce innovative This has led the Japanese to develop reduce massively the friction between coatings for its range of cutting tools, super fine levels of coating through the insert and workpiece. placing emphasis on the relationship application of nano-technology Also, the between the coating and the carbide principles. The thickness of each of the substrate. It is fully expected that coating layers – over 2000 of them – parting and grooving totals less than 3 micron. systems will Already a Sumitomo standard, the Sumitomo ZX coatings have a film-like thickness that allows cutting edges to remain sharp after the coating process, enabling high shear geometries to form part of the insert design that reduces cutting force and permits higher feed rates on lower powered machines using higher feed rates. The ZX coating is 4000 Hv, almost as hard as CBN which itself is almost as hard as diamond, yet Sumitomo’s latest

Walter’s PVD Tiger.Tec provides a wear- resistant, defined cutting edge, and maintain a controllable edge temperature

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TOOLING

coated carbide (PVD-AL2O3). Traditionally, aluminium oxide could Coating types only be applied with the CVD process at high temperature, efficient for plain Today’s coatings are typically applied using PVD (physical vapour deposition) or carbon materials but compromised CVD (chemical vapour deposition) techniques. Common coatings include: when cutting chrome or nickel alloys due ❐ Titanium nitride (TiN) – a general purpose PVD coating that increases hardness to loss of cutting edge definition and and has a high oxidation temperature high cutting temperatures. Walter’s ❐ Titanium carbo-nitride (TiCN) – the addition of carbon adds more hardness and PVD-Al2O3 Tiger.tec inserts provide a better surface lubricity wear-resistant, defined cutting edge, ❐ Titanium aluminium nitride (TiAlN) – a formed layer of aluminium oxide gives while maintaining controllable edge this tool better life in high heat applications temperature. ❐ Chromium nitride (CrN) – the anti-seizure properties of this coating Also utilising a basic

make it preferred in situations where built-up edge is common AL2O3 aluminium oxide ❐ Diamond – a CVD process that offers the highest performance structure is Seco’s new available for working non-ferrous materials such as graphite, metal TP2500 turning grade, matrix composites and high silicon aluminium. which is applied using the company’s innovative “Duratomic” process. The grade is targeted at P15- nano-technology coating is called Super covers a range of P30 applications, as well ZX, which has a hardness value of 5300 machining tasks. One as stainless steel turning Hv. Super ZX is a multilayer PVD coating supplier offering an and cast iron turning, that is formed using thousands of ‘umbrella’ solution is Sandvik Coromant effectively machining in the M20 and alternate titanium aluminium nitride – its new GC4225 insert grade is able to K30 application areas. and aluminium chromium nitride film machine steels in the P25 spectrum from layers. Compared with common low carbon through to high alloy. ATOMIC MANIPULATION titanium aluminium nitride coats, this Durability is improved, partly through Seco’s Duratomic process (insert, above) new PVD coating offers improved the insert’s ability to better withstand employs new process methods and hardness and oxidation resistance. both thermal demands and physical crystallographic control to manipulate Another new coating from variations. This is achieved by removing the coating at the atomic level. Sumitomo, the Super FF, is a smooth the gold TiN coating, which has a Duratomic grew out of Seco’s search to multilayer thin film structure comprised number of additional benefits. These develop a grade with a new level of wear of titanium carbo-nitride and aluminium include the reduction in built up edge, resistance and toughness, two oxide film. This gives a higher resistance improved resistance to coating flaking characteristics that have always been to chip adhesion and edge wear than and increased edge line toughness. All diametrically opposed. conventional CVD coatings. Super FF these advantages combine to make it The IMC Group includes Iscar, coated grades are recommended for cast more suitable for wider application Ingersoll and TaeguTec, so its president irons and ductile irons within the broad area of general steel Jacob Harpaz is an important voice in the turning, including extremely tough cutting tool sector and he has his own DIAMOND LIKE CARBON automotive crankshaft forgings, where opinions on the subject of coating trends. Other new coating developments at Sandvik tests show highly advantageous “PVD tooling now accounts for Sumitomo Electric Hardmetal include results. 56 per cent of global cutting tool DLC (diamond like carbon) for the dry Also new from Sandvik is its versatile consumption as opposed to 20 per cent machining of aluminium using its GC4230 insert grade, which is optimised in 2000,” he says. “Uncoated cutting Wavemill Auroracoat inserts. DLC is an for light to heavy milling of alloyed and tools are set to disappear as there is now amorphous film that is more like carbon unalloyed steels. Sandvik says that no real need for them. Why do than diamond. It is a hard, thin film that “stressless” coating technologies help customers still use HSS? There are new features high hardness, superior ensure this new grade brings improved generations of coatings that can be PVD tribology properties and excellent edge line toughness far beyond standard applied to maintain sharp edges on adhesion resistance. It has a low friction CVD grades. tooling – this leaves no excuses.”■ coefficient when used without lubricant. At Walter, recent emphasis has been Many machine shops will be on the development of what it calls the Enter 110 at interested in sourcing a solution that world’s first PVD aluminium oxide www.machinery.co.uk/enquiry

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