How to Choose the Right Cutting Inserts

Issuing time:2026-01-18 11:37


1705653992851.pngI. Core Selection Principles: Prioritize "Compatibility" First

Selecting cutting inserts essentially boils down to "precise matching of working conditions and performance"—discussing insert selection without considering the machining scenario is meaningless.
The three core principles to follow:

  1. Material Compatibility First: The workpiece material’s hardness, thermal conductivity, and work hardening tendency directly determine the insert material, coating, and geometric angles (e.g., high-toughness inserts for stainless steel, anti-adhesion designs for aluminum alloys).

  2. Process Requirement Orientation: Rough machining prioritizes impact resistance; finish machining emphasizes sharpness and precision; semi-finishing balances both performance aspects.

  3. Parameter Synergy Optimization: Insert dimensions, nose radius, lead angle, and other parameters must be compatible with cutting speed and feed rate to avoid overall performance imbalance caused by optimizing a single parameter in isolation.

II. Step-by-Step Selection Process: From Basic to Advanced

(1) Step 1: Lock Insert Material and Coating Based on Workpiece Material

Significant differences in cutting characteristics between materials require targeted matching of core insert properties:


Workpiece Material Category

Key Cutting Characteristics

Recommended Insert Material

Suitable Coating & Design

Steel (Carbon Steel, Alloy Steel)Continuous chips, medium hardnessCemented Carbide (ISO P Class)CVD-Al₂O₃+TiCN coating for quenched and tempered steel; PVD-TiAlN coating + positive rake angle groove for low-carbon steel
Stainless Steel (304, 316)Severe work hardening, high stickinessUltrafine-Grain Cemented CarbideTiAlN coating + sharp cutting edge (e.g., VF groove), avoiding edge dulling
Cast Iron (HT250, Ductile Iron)Discontinuous brittle chips, abrasiveCeramic (SiAlON), CBNNegative rake angle inserts for rough machining; BNK30 inserts dedicated to high-silicon cast iron
Aluminum Alloy, Copper AlloyEasy adhesion, low hardnessPCD (Polycrystalline Diamond)Rake angle ≥15° + edge polishing (Ra.2μm), uncoated design
Superalloys, Titanium AlloysHigh cutting force, poor thermal conductivityHigh-Toughness Cemented Carbide (ISO S Class), CeramicAlTiN coating + small nose radius (rε=0.4mm), high-pressure cooling



(2) Step 2: Determine Insert Geometric Parameters Based on Machining Process通用模板1.png

  1. Nose Radius (rε):

    • Rough machining: Select large radius (0.8-1.2mm) to enhance impact resistance.

    • Finish machining: Choose small radius (0.2-0.4mm) to ensure surface precision.

    • Thin-walled part machining: Control radial force with radius ≤0.4mm.


  2. Rake Angle & Clearance Angle:

    • Soft materials (aluminum alloy, low-carbon steel): Positive rake angle (≥15°) + large clearance angle (P Class 11°) to reduce cutting resistance.

    • Hard materials (high-hardness steel, cast iron): Negative/small rake angle + small clearance angle (N Class 0°) to strengthen edge rigidity.


  3. Lead Angle:

    • Large lead angle (90°): Suitable for turning shoulders, reducing vibration.

    • Small lead angle (45°-60°): Distributes cutting load, reduces flank wear, ideal for superalloy machining.


(3) Step 3: Interpret Insert Model to Confirm Dimensional and Precision Compatibility

Insert models are "condensed codes" for parameters. Mainstream ISO standard models (e.g., TNMG160408) can be decoded as follows:

  • Prefix Letter: Represents insert shape (T = Triangular 60°, versatile; C = Diamond 80°, impact-resistant; V = Diamond 35°, suitable for finish machining).

  • Middle Letters: Indicate clearance angle (N=0°, M=7°, P=11°) and tolerance class (M = Medium tolerance, general machining; G = High precision, mass precision machining) in sequence.

  • Suffix Numbers: First two = Insert side length (mm); middle two = Insert thickness (mm); last two = Nose radius (in 0.1mm units, e.g., "08" = 0.8mm).

Example: TNMG160408 stands for "Triangular insert + 0° clearance angle + Medium tolerance + 16mm side length + 4mm thickness + 0.8mm nose radius", suitable for steel rough machining.

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(4) Step 4: Optimize Groove Selection Based on Cutting Conditions

Groove design directly affects chip breaking and cutting stability:

  • Rough machining: Wide-deep grooves (e.g., CNMG series) for enhanced chip breaking, compatible with large depth of cut and high feed rate.

  • Finish machining: Narrow-shallow grooves + Wiper edge design (e.g., WMX groove) to improve surface finish, enabling 30%+ higher feed rate.

  • Intermittent cutting/harsh conditions: Tough edge grooves (e.g., WR groove) to avoid chipping; prioritize double-sided negative rake angle inserts for rigidity.

III. Common Selection Mistakes and Solutions刀片后背图.png

  1. Focusing on Model While Ignoring Material Marking: Confusing ISO classifications (P = Steel, M = Stainless Steel, K = Cast Iron). Using P-Class inserts for stainless steel causes adhesion and chipping—always verify material labels on insert packaging.

  2. Misunderstanding Nose Radius Units: Mistaking "05" for 5mm (actual = 0.5mm) leads to dimensional deviations. Remember suffix numbers are in 0.1mm units.

  3. Mixed Use of Rough/Fine Machining Inserts: Fine machining inserts crack easily in rough machining; rough machining inserts leave tool marks in finish machining. Distinguish by edge features (fine-ground edges for finishing, thick edges for roughing).

  4. Neglecting Coating-Cooling Matching: Using CVD coating (high heat resistance) for superalloy machining without high-pressure cooling causes coating detachment. Adjust cutting parameters based on coating properties.


IV. Extending Service Life

  1. Parameter Optimization: Insert life is inversely proportional to cutting speed and feed rate. For superalloy machining, control cutting speed ≤100m/min and feed rate 5mm/r to avoid excessive wear.

  2. Maintenance Tips: Regularly inspect edge wear (replace when flank wear exceeds 0.3mm); avoid dry cutting (except for aluminum alloy); use emulsion cooling to extend life by 50%+.

Article classification: 常见问题技术支持
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