# Seco Adds TP3502 CVD Grade for Interrupted Steel Turning https://cncoutlook.com/news/seco-tp3502-duratomic-steel-turning/ By CNC Outlook Editorial · 2026-09-29 Seco has added TP3502 to its Duratomic range of carbide turning grades, targeting ISO P steel operations in which cutting conditions change during a pass. The September 29, 2026 release positions the CVD-coated insert grade for variable material hard Seco has added TP3502 to its Duratomic range of carbide turning grades, targeting ISO P steel operations in which cutting conditions change during a pass. The September 29, 2026 release positions the CVD-coated insert grade for variable material hardness, interrupted cuts and mixed turning conditions. Those operating conditions can be harder to manage than an uninterrupted finishing cut, because the cutting edge experiences changing mechanical and thermal loads. The announcement is therefore most relevant to shops machining forgings, cast features, keyways and other parts with repeated entry and exit of the cutting edge. ## The engineering problem behind interrupted steel turning An interrupted cut produces repeated load cycles rather than a steady engagement between insert and workpiece. Depending on insert geometry, toolholder stiffness and process conditions, those cycles can promote micro-chipping, edge fracture or accelerated coating damage. At the same time, a grade optimized only for edge toughness may sacrifice wear resistance during long periods of continuous cutting. Seco describes TP3502 as balancing those competing requirements through its substrate and CVD-coating design, with the grade positioned in the ISO P35 application range. That classification is a useful starting point, but it is not a substitute for application data. ISO P covers a broad range of steels, while P35 indicates an application orientation rather than a unique steel specification or feed-rate recipe. Shops may encounter very different cutting forces and chip formation on low-carbon steel, an alloy forging or a hardened zone in a welded assembly. The correct insert selection must also consider the chipbreaker, nose radius, coolant strategy and rigidity of the complete turning system. ## How the launch should be assessed Seco emphasizes predictable tool life rather than simply the highest possible cutting speed. Predictability can be commercially important in automated turning, where a failed edge may damage several workpieces before an operator returns. But a supplier's description of stable cutting does not demonstrate a universal percentage improvement for every shop. A controlled comparison should use identical material batches and comparable geometry, record spindle load, wear progression, surface condition and the number of accepted components per edge. The benchmark should also distinguish catastrophic edge failure from gradual flank or crater wear. A tool that runs for more minutes but produces unstable dimensions toward the end of life may offer little practical benefit. In many turning cells the meaningful measure is accepted-part cost, including tool changes and unplanned interruptions, rather than insert price or nominal life alone. For critical workpieces, dimensional stability and burr formation across the edge-life window belong in the test report. ## Implications for CNC production For a shop running both interrupted and continuous cuts on related steel components, an insert grade with wider operating tolerance could simplify inventory and production planning. That potential remains an application-specific hypothesis until tested. Engineers should confirm whether existing holders, insert geometries and programmed cutting data are compatible, and request recommended starting conditions for the exact material group. Any change to roughing strategy should also be checked against finished-part requirements and the available machine power. TP3502 is a meaningful product addition because it addresses the robustness of routine turning operations, not just headline metal-removal rates. Seco's announcement provides the grade positioning and intended applications; it does not replace a documented plant trial under representative conditions. Source: Seco's September 29, 2026 Duratomic TP3502 announcement. ## Sources & References - [Duratomic® technology raises the bar for steel turning]() — Seco Tools (2026-09-29T12:00:00Z) © CNC Outlook. See https://cncoutlook.com/terms/ for reuse terms.