Sweden's Seco Tools undertook the largest simultaneous launch of cutting tool tips in its history last month, introducing new Duratomic-coated inserts. Subsidiary Seco Tools (UK) is the focal point for this in the UK.

With the simultaneous introduction of three insert grades having a steel turning focus, the cutting tool company is replacing 1,200 existing inserts at a stroke; although new and replaced products will run in parallel for a time. "It's the biggest launch we have ever had; probably the biggest anybody has ever had," informs Seco Tools (UK)'s turning products manager, John McGhee. A grade-at-a-time introduction is the more usual approach.

Although it is not given the name, the new coating is Duratomic mark two. Seco introduced Duratomic, which has a distinctive black finish, in 2007. That was a "revolution", delivering far improved performance and representing the largest ever product launch at that time. This year's Duratomic development is hailed "a game changer" by Seco Tools (UK) managing director Richard Jelfs. What's more, he promises similar such product/service launches every year up to and including 2019, targeting a UK turnover of £50 million in 2019 off the back of that.

But let's stick with Duratomic. First off, it's not black anymore; it's chrome. And that is one of its nine emphasised features, in fact (see box: 'Nine Duratomic benefits'). This colouring, courtesy of a chrome flash coating, makes it far easier to detect a worn-out insert; the blackened wear area showing up clearly against the chrome surface and discourages early disposal of part-worn tips.

Chrome flashing makes wear easier to spot


In addition, this flash chrome coating helps reduce adhesive wear on the insert caused by notching, as well as reducing component surface roughness issues commonly associated with Al203 coatings.

What new Duratomic shares with its predecessor, however, is the 2007 revolution of an improved coating structure that vertically aligns the crystals of the top

The vertical column structure of the Al2O3 coating is visible; better nucleation between the Al2O3 coating and the TiCN coating below is also a feature of new Duratomic

CVD-applied aluminium oxide (think columns), as opposed to a more variable, inclined structure (see image, p. 30). The former is much harder and tougher, and also dissipates heat more effectively. (Think of graphite and diamond – same substance, different properties.) It is this modified structure that allowed Seco Tools in 2007 to claim Duratomic as "the world's first atomically modified coating", in fact.

The upshot of that initial development was inserts that were tougher, more wear-resistant and able to operate at higher cutting speeds in the ISO P application area for steels and stainless steels, but with cast iron (ISO K) machining needs also catered to. And, although the inserts didn't cover all steel machining needs – extremes in fine and rough machining weren't handled – their success can be judged by the fact that Seco Tools has sold 100 million inserts globally over seven years, taking in turning, milling and drilling application areas.

This latest launch sees the turning area covered initially, and while steels are the main focus, stainless steels and cast irons can also be machined with the current grades. So the new Duratomic range of three grades extends application areas of three earlier grades (TP3500 currently remains), as well as enlarging the cutting data envelope (cutting speed, feed rate and axial depth of cut) as well. A fourth grade will extend the supported application areas into unstable cutting conditions, replacing the TP3500 grade with TP3501.

Key to improved performance of the new Duratomic coating has been Seco Tools' 'playing around' with the relative thicknesses of the TiCN coating that sits between the carbide substrate and the outer aluminium oxide coating. There has also been improved bonding (nucleation) between those two coating layers, combating separation tendency. Better coating thickness control, better coating texture control and high energy surface post-treatment also deliver various improved properties, while the carbide substrate has also seen attention.


So, turning to the grades themselves and their operating areas, offering crater wear resistance at high cutting speeds (stable conditions) is TP0501 (replacing TP0500), covering the P3, P5, P7, K1 ISO application areas and designed for peak application in high alloy steel.

Withstanding flank wear at moderate cutting speeds is TP1501, covering the P2, P4, P6 and K4 application areas and tuned for low-alloy steels.

For semi-stable conditions there is TP2501. This covers the ISO application ranges P1 through P7, K1 and K4, plus M1 and M2. (The forthcoming TP3501 will be applicable in the M range only.)

And so to real world benefits. Examples offered by Seco Tools include a 50% boost to tool life and no occurrence of broken edges for TP2501 versus first generation Duratomic TP2500 when longitudinally turning 34CrNiMo6 (SMG P5) with coolant applied, taking in both continuous and interrupted cutting, at 250 m/min cutting speed, 2.5 mm axial depth of cut and 0.35 mm/rev.

For TP1501 versus TP1500, continuous cutting (facing and longitudinal turning) of 20MnCr5 forged steel (SMG P3) with coolant applied saw tool life boosted by 200% at 285 m/min cutting speed, axial depth of cut 2.6 mm and feed rate of 0.38 mm/rev. This application is described as a demanding set-up where there was variation of workpiece properties.

Finally, for TP0501 versus TP0500, continuous and interrupted cutting of 38MnVS6 forged steel, 900 MPa, (SMG P5) with coolant applied saw a 200% increase in resistance to flank wear, despite the interrupted cut conditions. Cutting data was 200 m/min cutting speed, axial depth of cut 1.5 mm and feed rate 0.35 mm/rev.

Additional information:

Nine Duratomic benefits

Seco Tools underlines nine key benefits/ambitions for the new Duratomic inserts:

  • Edge intelligence – crystal-clear indication of used edges, even after just a few seconds. Up to 20% of inserts are thrown away not fully used, Seco Tools (UK) says
  • Thinking green – approximately 30% of each new insert is made from reclaimed or recycled inserts
  • Premium quality – reduced deviation in mean properties gives better tool life, and reduced deviation in shape and size means more consistent insert dimension
  • Adopted grade design – by varying the major product attributes, such as coating thickness and substrate, performance has been optimised and tailored to the target machining area for each Duratomic grade. This approach is an industry first
  • Duratomic mission – to make the "best turning insert in the world" even better, in all turning applications
  • Complete grade chain – the first time Seco Tools has launched three grades simultaneously to cover the full range of steel machining (except, currently, unstable machining)
  • Edge reliability – new post-treatment improves edge toughness and resistance to chip hammering and fatigue properties in dynamic load situations
  • Product support – information at users' fingertips' through My Pages at the Seco Tools website
  • Duratomic technology – longer tool life creating cost reductions and improved productivity. Improved reliability by way of predictable wear, benefiting part accuracy, part quality and surface finish.

More to come in 2015

This year, Seco Tools will launch 3,700 new products, of which Duratomic accounts for 1,200; the greatest number in one year ever for the company. In previous years, 1,000-2,000 would have been more usual, but these new launches may be additions to ranges or grade extensions, rather than a "game-changer" such as Duratomic.

First published in Machinery, May 2015