CNMG 120408 Chip Breaker BMF Grade FM2553 / CNMG 432 BMF #FMCarbide

CNMG 120408 / CNMG 432, chip breaker BMF, grade FM2553 — negative 80° rhombic turning insert.

1/2" inscribed circle, 3/16" thick, 1/32" corner radius. The BMF breaker is the finishing geometry: 0.003–0.012 ipr (0.07–0.3 mm/rev) at 0.01–0.06" (0.2–1.5 mm) depth of cut. FM2553 is a CVD (Al₂O₃) grade — tough substrate for heavy interrupted cuts in steel and stainless, heavy roughing in mild steel, and first choice for superalloys.

Specifications

• Insert designation (ISO): CNMG 120408
• Insert designation (inch): CNMG 432
• Insert shape: 80° rhombic (C)
• Clearance angle: 0° — negative (N)
• Tolerance class: M
• Insert type: G — with hole, chipbreaker both sides
• Inscribed circle (I.C.): 1/2" (12.7 mm)
• Thickness: 3/16" (4.76 mm)
• Corner radius: 1/32" (0.79 mm)
• Chip breaker: BMF — Stainless steel — finishing
• Feed rate range: 0.003–0.012 ipr (0.07–0.3 mm/rev)
• Depth of cut range: 0.01–0.06" (0.2–1.5 mm)
• Grade: FM2553
• Coating: CVD (Al₂O₃)
• ISO application range: P20–P35 · M10–M30
• Cutting speed, non-alloy steel: 490–1150 SFM (150–350 m/min)
• Cutting speed, low-alloy steel: 300–980 SFM (90–300 m/min)
• Cutting speed, high-alloy steel: 230–820 SFM (70–250 m/min)
• Cutting speed, ferritic & martensitic stainless: 390–750 SFM (120–230 m/min)
• Cutting speed, austenitic stainless: 260–660 SFM (80–200 m/min)
• Cutting speed, titanium & super-alloys: 110–260 SFM (35–80 m/min)

Tool holders that accept this insert

69 RMC toolholders in stock take this insert — 80° rhombic, 0° — negative clearance, 1/2" inscribed circle, 3/16" thick. Pick by the shank your turret takes.

RMC square-shank toolholders — made in the USA

Boring bars and interchangeable heads. 66 more RMC tools take the same insert for internal turning. See RMC boring bars →

TURNING KNOW-HOW

Get more from your turning inserts.

Practical guides to choosing, understanding and using your inserts.

01 / SELECTION

Grades & chip breakers

Explore the grade and chip-breaker selection chart for your turning operation.

Explore the chart → 02 / INSERT CODES

Know your insert

Understand turning-insert designations and what the letters and numbers mean.

Read the guide → 03 / CUTTING PARAMETERS

Turning calculations

Learn how to use a turning formula calculator to work through the numbers.

Explore the formulas →