WNMG Inserts — Grades and Cross-Reference

Compiled 2026-04-04 · 40 chunks, 6 posts · turning · inserts · carbide · indexable · tooling

Summary

WNMG inserts are 80° diamond-shaped turning inserts with 7° clearance angles, designed for general-purpose external turning operations. The "W" designation indicates the 80° included angle, "N" denotes the 7° clearance, "M" specifies the manufacturing tolerances, and "G" indicates the hole and chipbreaker configuration. These inserts excel in roughing and semi-finishing operations across various materials, offering versatility between the aggressive cutting of [[cnmg-inserts]] and specialized finishing inserts.

Insert Geometry and Applications

WNMG Shape Characteristics

  • Included Angle: 80° (more acute than CNMG's 80° but different geometry)
  • Clearance Angle: 7°
  • Cutting Edges: 4 usable edges per insert
  • Typical IC Range: 3/8" to 3/4" (432, 542, 644, 844 sizes)
  • Nose Radius Options: 0.4mm, 0.8mm, 1.2mm, 1.6mm typically

Size Designations

Insert Size IC (inches) Thickness Applications
WNMG 332 3/8" (9.525mm) 3.18mm Light roughing, finishing
WNMG 432 1/2" (12.7mm) 4.76mm General purpose turning
WNMG 542 5/8" (15.875mm) 5.95mm Medium-heavy turning
WNMG 644 3/4" (19.05mm) 6.35mm Heavy roughing

Speeds and Feeds by Material

Steel (General Purpose)

Manufacturer recommendations vs. shop floor reality:

  • Catalog SFM: 400-800 for uncoated, 600-1200 for coated
  • Actual shop practice: Start 20% lower, especially on older lathes
  • Feed rates: 0.008-0.020 IPR for finishing, 0.015-0.040 IPR for roughing
  • Depth of cut: 0.050-0.300" typical

[[4140-steel]] (Heat Treated)

  • SFM: 300-600 (use tougher P-grade inserts)
  • Feed: 0.010-0.025 IPR
  • Shop tip: Maintain constant feed to prevent work hardening

[[304-stainless]]

  • SFM: 200-400 (keep cutting constant to avoid work hardening)
  • Feed: 0.012-0.030 IPR minimum
  • Depth: 0.080"+ minimum to get under work-hardened layer
  • Critical: Never let insert rub or dwell

[[cast-iron]]

  • SFM: 500-1000+ (can run very fast)
  • Feed: 0.015-0.050 IPR
  • Use: Uncoated or specific CI grades, avoid built-up edge

[[aluminum-6061]]

  • SFM: 1000-3000+
  • Feed: 0.008-0.025 IPR
  • Note: Sharp uncoated inserts often outperform coated for aluminum

Grade Selection and Cross-Reference

Major Manufacturer Grades

Sandvik/CoroTurn:

  • GC1025: Uncoated P25, general steel turning
  • GC1515: CVD coated P15, steel roughing to semi-finishing
  • GC4225: PVD coated for stainless steel
  • GC2015: Uncoated for aluminum and non-ferrous

Kennametal:

  • KC850: Uncoated P20-P30 equivalent
  • KC5010: CVD coated for steel
  • KC720: For stainless steel applications
  • KC990: Aluminum grade

Seco:

  • TP1500: Uncoated general purpose
  • TP2500: CVD coated steel grade
  • TS2000: Stainless steel grade

Mitsubishi:

  • UE6020: General purpose coated
  • US735: Uncoated for aluminum
  • VP15TF: Tough steel grade

Kyocera:

  • CA5525: PVD coated steel grade
  • PR1225: Uncoated general purpose

Cross-Reference Chart

Application Sandvik Kennametal Seco Mitsubishi
Steel Roughing GC1515 KC5010 TP2500 UE6020
Steel Finishing GC1025 KC850 TP1500 UP20M
Stainless Steel GC4225 KC720 TS2000 VP15TF
Aluminum GC2015 KC990 TP0500 US735
Cast Iron GC1010 K68 TK1000 MB8025

Chipbreaker Selection

Common Chipbreaker Codes

  • -MF: Medium finishing, versatile across materials
  • -MM: Medium machining, general purpose
  • -MR: Medium to rough, higher feed rates
  • -RG: Rough machining, heavy cuts
  • -LF: Light finishing, delicate work

Practical Chipbreaker Selection

Shop floor wisdom often differs from catalogs:

  • Start with -MM for general work
  • -MF works well for interrupted cuts despite "finishing" designation
  • -MR handles higher feeds better than catalogs suggest
  • Positive chipbreakers reduce cutting forces on weaker setups

Toolholder Compatibility

Common WNMG Toolholders

  • External turning: MWLNR, MWXNR series
  • Entering angles: Typically 95°, 93°, or 91°
  • Shank sizes: 3/4", 1", 1.25", 1.5" common

Setup Considerations

  • Toolholder rigidity: Critical for chatter prevention
  • Overhang ratio: Keep under 4:1 length to diameter when possible
  • Insert seating: Ensure proper support, especially on negative inserts

Common Problems and Solutions

Chatter Issues

  • Symptom: Poor surface finish, tool marks
  • Solutions: Reduce overhang, increase rigidity, try different nose radius
  • Shop tip: Sometimes going to smaller insert size helps

Poor Tool Life

  • Worn flank: Reduce speed, increase feed
  • Chipped edge: Reduce feed, check for interrupted cut capability
  • Cratering: Reduce speed, try tougher grade

Built-Up Edge (BUE)

  • Common in: Stainless steel, some alloys
  • Solutions: Increase speed, maintain constant feed, sharp geometry
  • Alternative: Try uncoated insert if coated is building up

Work Hardening

  • Prevention: Maintain constant feed, adequate depth of cut
  • Recovery: Use tougher grade, ceramic if available for the application

Shop Floor Tips

Insert Selection Reality

What experienced machinists actually do differently from textbooks:

  • Many prefer WNMG over [[cnmg-inserts]] for versatility despite lower strength
  • Uncoated inserts often outperform coated in aluminum despite marketing claims
  • Larger nose radius helps finish but can cause chatter on flexible setups
  • Keep variety of chipbreakers in stock; -MM covers 80% of applications

Economic Considerations

  • Insert cost: WNMG typically costs less than equivalent CNMG
  • Inventory: Four cutting edges make them cost-effective
  • Versatility: One insert type handles wide range of operations

Troubleshooting Sequence

  1. Check setup rigidity first before blaming insert
  2. Verify speeds/feeds against actual machine capability, not just charts
  3. Try different nose radius before changing grade
  4. Consider workpiece material variations (especially in stainless grades)

Storage and Handling

  • Store in original packaging to prevent edge damage
  • Inspect cutting edges before installation
  • Rotate through insert edges systematically for maximum economy
  • [[cnmg-inserts]] — Alternative diamond insert with different geometry
  • [[insert-selection-guide]] — Comprehensive guide to insert selection criteria
  • [[turning-basics]] — Fundamental turning operations and setup
  • [[tool-wear-diagnosis]] — Identifying and correcting insert wear patterns
  • [[chatter-vibration]] — Solving vibration problems in turning operations
  • [[4140-steel]] — Specific considerations for heat-treated steel turning
  • [[304-stainless]] — Stainless steel turning challenges and solutions
  • [[toolholder-selection]] — Matching toolholders to insert geometry