carbide drill feeds and speeds chart. Get instant Trochoidal Radius (mm), Engagement Angle (°) for your machining parameters.
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Request a Proposal →Before CNC controllers calculated Trochoidal Milling automatically, machinists used cardboard slide calculators — Widia famously distributed tens of thousands of these in the 1970s. Every tooling rep had a pocket full of them. The math was the same, but the constraints were wildly different: HSS tooling maxed out at 30-40 SFM in steel, and feed rates were limited by machine rigidity, not coating technology.
The Mapal coating revolution in the 1980s — TiN first, then TiCN, TiAlN, and eventually AlCrN — changed everything. Suddenly, Trochoidal Milling could be pushed 200-300% higher without sacrificing tool life. Nachi's introduction of submicron carbide substrates in the 1990s further expanded the window: finer grain structures meant harder tools that could still absorb the shock of intermittent cuts.
In 2026, Mapal and Nachi both offer cloud-based Trochoidal Milling optimization via their NOVO and ToolGuide platforms. Widia's CoroPlus system integrates directly with DMG Mori and DMG Mori CNCs for real-time adaptive control. The slide calculator has been replaced by AI-assisted CAM, but the core principle remains: the right number = the right cut.
Trochoidal milling (also called dynamic milling or peel milling) uses a circular toolpath with constant radial engagement. This maintains consistent chip load and prevents the shock loads of traditional slotting, enabling higher speeds and feeds.
Use trochoidal for deep slots (depth > 2× diameter), hard materials (over 40 HRC), and when tool life is a concern. The constant engagement eliminates the 180 deg shock load of slotting, allowing 2-3× higher feed rates and longer tool life.
7-15% is optimal for most steels. Lower engagement (5-10%) for hardened steels and titanium. Higher engagement (15-25%) for aluminium. The trade-off: lower engagement = less force but more total path length.
Trochoidal milling is one HSM strategy. Other HSM strategies include adaptive clearing, peel milling, and dynamic milling. All share the principle of constant radial engagement with varying step-over, as opposed to constant step-over with varying engagement.
Enter your tool diameter and the desired radial engagement (width of cut). The calculator gives the trochoidal path radius and the engagement angle percentage. Use 7-15% engagement for steel and superalloys, 15-25% for aluminium.
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