Description
CARBIDE TURNING INSERTS TNMA
TNMA carbide turning inserts are double-sided, negative-geometry triangular (60°) inserts featuring a 0° relief (clearance) angle. These inserts are commonly produced with a flat top (no chipbreaker) or with a K-land/honed edge and are designed primarily for cast-iron and short-chipping material turning, as well as for general medium-to-heavy turning and interrupted cuts. TNMA inserts offer high edge strength, toughness and dependable performance in demanding conditions.
Made from cemented carbide (WC-Co) and typically CVD or PVD coated (or uncoated for some cast-iron grades), TNMA inserts combine edge toughness, thermal stability and multi-index economy, ensuring reliable results in roughing and general turning applications. Many TNMA variants are specifically recommended by manufacturers for cast iron work.
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Key Features
• Shape: Triangle (T) — 60° included angle.
• Relief Angle: 0° (negative geometry).
• Cutting Edges: Double-sided — typically 6 usable cutting edges (triangular double-sided indexing). Mounting Type: Clamp or screw-on with central hole / cylindrical seat (ISO standard clamping).
• Coatings: CVD or PVD (TiN / TiCN / Al₂O₃ / TiAlN variants) or uncoated depending on grade and intended material.
• Application Type: Cast-iron turning, general medium-to-heavy turning, interrupted cuts and operations requiring robust edge strength.
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Materials & Applications
TNMA carbide inserts are optimized for operations where edge strength and toughness are more important than the lowest cutting force or mirror finishes. Typical uses include:
Typical Workpiece Materials:
• Cast Iron (gray & ductile) — widely recommended; excellent for continuous and interrupted roughing.
• Steel (carbon & alloy) — suitable for heavier roughing and general turning with appropriate grades.
• Stainless Steel — possible with appropriate grade/coating but not the primary target.
Common Operations:
• Heavy and medium roughing of cast iron and steels
• Interrupted cuts and high radial engagement operations
• General turning where a strong, honed edge (K-land) is required for edge security.
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Advantages & Performance
• High toughness & edge strength: Negative geometry and common edge hones / K-lands provide resistance to chipping in interrupted or heavy cuts.
• Multi-index economy: Double-sided triangular design typically yields 6 effective edges per insert, lowering cost per edge.
• Reliable on cast iron: Many TNMA grades and chipbreaker/edge treatments are specifically optimized for short-chipping materials.
• Versatile coatings: CVD/PVD options extend life across abrasive and high-temperature conditions typical in heavier turning.
