Turning Inserts — Complete Cross-Reference

Compiled 2026-04-04 · 40 chunks, 11 posts · turning · inserts · carbide · indexable · lathe · speeds-feeds

Summary

Turning inserts are indexable carbide cutting tools used on lathes for external and internal turning operations. This cross-reference covers insert identification, geometry selection, grade matching, and real-world speeds/feeds across common materials. Unlike fixed tooling, indexable inserts offer multiple cutting edges per insert, reducing per-part tooling costs while providing consistent performance through proper insert selection and application.

Insert Classification System

Standard Insert Designation (ISO)

Format: CNMG 432 GP

  • C = Shape (80° diamond)
  • N = Clearance angle (0°)
  • M = Tolerance class (±0.13mm)
  • G = Chip breaker type
  • 4 = Insert size (1/2" inscribed circle)
  • 3 = Thickness (3.18mm)
  • 2 = Nose radius (0.2mm/0.008")
  • GP = Grade designation

Common Insert Shapes

Shape Angle Code Application
Diamond 80° C General purpose turning
Diamond 60° D Light cuts, threading
Square 90° S Face turning, shoulders
Triangular 60° T Light finishing cuts
Round - R Interrupted cuts, roughing

Material-Specific Applications

Steel (4140, 1018-1045)

CNMG inserts recommended for general turning

  • Surface speed: 400-800 SFM
  • Feed: 0.008-0.020 IPR
  • Depth of cut: 0.050-0.250"
  • Grade: Uncoated or TiN for general work, TiAlN for higher speeds

Forum consensus: "CNMG 432 with 0.008 nose radius covers 80% of steel turning jobs. Start at 600 SFM in 4140, back off if you get built-up edge."

Stainless Steel (304, 316, 17-4PH)

DNMG or VNMG for work-hardening materials

  • Surface speed: 200-400 SFM
  • Feed: 0.010-0.015 IPR (keep feed up to avoid work hardening)
  • Depth of cut: 0.030-0.150"
  • Grade: Sharp edge geometry, positive rake

Shop floor tip: "Never let stainless rub. Light cuts work-harden it. Take 0.010" minimum or go home."

Aluminum (6061, 7075)

Sharp DCMT or CCMT inserts

  • Surface speed: 800-2000 SFM
  • Feed: 0.015-0.030 IPR
  • Depth of cut: 0.100-0.500"
  • Grade: Uncoated carbide, polished edge

Cast Iron

CNMG or WNMG for interrupted cuts

  • Surface speed: 500-1200 SFM
  • Feed: 0.010-0.025 IPR
  • Depth of cut: 0.050-0.300"
  • Grade: Uncoated carbide, tough substrate

Insert Geometry Selection

Nose Radius Guidelines

Nose Radius Application Finish Stability
0.008" (0.2mm) Light finishing Best Low
0.016" (0.4mm) General purpose Good Medium
0.031" (0.8mm) Medium roughing Fair High
0.063" (1.6mm) Heavy roughing Poor Highest

Clearance Angle Selection

  • 0° (N): Strongest edge, general purpose
  • 7° (P): Better clearance, lighter cuts
  • 15° (B): Maximum clearance, delicate work

Chip Breaker Types

  • M: Medium breaking, general purpose
  • F: Light breaking, finishing
  • R: Heavy breaking, roughing
  • G: Wide range, interrupted cuts

Major Manufacturer Cross-Reference

Application Sandvik Kennametal Seco Iscar
General steel turning CNMG 432-PM CNMG 432-K313 CNMG 432-M3 CNMG 432-IC907
Stainless finishing DNMG 331-PF DNMG 331-K313 DNMG 331-M5 DNMG 331-IC8250
Aluminum roughing CCMT 432-PF CCMT 432-K10 CCMT 432-M02 CCMT 432-IC20
Cast iron CNMG 543-QM CNMG 543-K68 CNMG 543-M3 CNMG 543-IC5010

Grade Selection by Material

Steel Grades:

  • Sandvik: GC4325 (general), GC4315 (high speed)
  • Kennametal: KC5025 (general), KC5010 (finishing)
  • Seco: TP1500 (general), TP2500 (high speed)

Stainless Grades:

  • Sandvik: GC4225, GC4235
  • Kennametal: KC5025, KC5410
  • Seco: TP0501, TP2000

Speeds and Feeds Calculator

Surface Speed Formula

RPM = (SFM × 3.82) / Diameter

Starting Parameters by Operation

Roughing (0.100-0.250" DOC):

  • Steel: 400-600 SFM, 0.012-0.020 IPR
  • Stainless: 250-400 SFM, 0.010-0.015 IPR
  • Aluminum: 1000-1500 SFM, 0.020-0.030 IPR
  • Cast Iron: 600-900 SFM, 0.015-0.025 IPR

Finishing (0.005-0.030" DOC):

  • Steel: 600-800 SFM, 0.005-0.012 IPR
  • Stainless: 300-500 SFM, 0.008-0.012 IPR
  • Aluminum: 1200-2000 SFM, 0.010-0.020 IPR
  • Cast Iron: 800-1200 SFM, 0.008-0.015 IPR

Common Problems and Solutions

Built-Up Edge (BUE)

Symptoms: Poor finish, increasing cutting forces Solution: Increase speed 20-30%, use sharper grade, improve coolant flow

Chatter Marks

Symptoms: Spiral marks on part surface Solution: Increase nose radius, reduce overhang, dampen setup, adjust speeds

Rapid Flank Wear

Symptoms: Insert edge wearing quickly Solution: Reduce speed 15-20%, check for excessive hardness, upgrade to harder grade

Chip Packing

Symptoms: Chips wrapping around tool Solution: Increase feed rate, change chip breaker geometry, improve coolant pressure

Shop Floor Tips

Insert Selection Priorities

  1. Size first: Match insert size to depth of cut and machine rigidity
  2. Shape second: Diamond (CNMG) for 80% of applications, square for facing
  3. Grade third: Uncoated carbide for most applications, coated for production
  4. Nose radius last: Start with 0.031" for general work

Practical Advice from Machinists

  • "CNMG 432 covers more jobs than any other insert. Stock these first."
  • "In stainless, never drop below 0.008" feed or you'll work-harden and fight all day."
  • "Aluminum needs speed. If you're not making chips fly, speed up."
  • "Cast iron loves uncoated carbide. Coatings just chip off."

Tool Life Optimization

  • Rotate to fresh edge at first sign of wear
  • Use consistent entry/exit points to distribute wear
  • Match insert grade to job length: tough grades for short runs, wear-resistant for production

Setup Considerations

  • Minimize tool overhang (3:1 maximum ratio)
  • Set insert height at centerline
  • Use rigid toolholders with maximum contact area
  • Maintain sharp tool geometry through proper tool holder selection
  • [[cnmg-inserts]] — detailed CNMG geometry and applications
  • [[wnmg-inserts]] — WNMG insert specifications and uses
  • [[turning-basics]] — fundamental turning operations and setup
  • [[cnc-lathe-setup]] — machine setup for indexable tooling
  • [[insert-selection-guide]] — systematic approach to insert selection
  • [[toolholder-selection]] — matching holders to inserts for optimal performance
  • [[4140-steel]] — specific parameters for 4140 steel turning
  • [[304-stainless]] — stainless steel turning techniques and speeds
  • [[aluminum-6061]] — aluminum-specific turning parameters
  • [[cast-iron]] — cast iron turning best practices
  • [[chatter-vibration]] — diagnosing and solving turning vibration issues
  • [[tool-wear-diagnosis]] — identifying and preventing insert wear patterns