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CNC ISO Nomenclature

 

CNC ISO Nomenclature

The ISO nomenclature system provides a standardized way to designate turning tool holders, boring tool holders, and indexable inserts, making it easier to identify their key features and dimensions.  

1. Turning Tool Holders

The ISO designation for turning tool holders typically consists of 7 to 9 positions (letters and numbers), each defining a specific characteristic of the holder. Here's a breakdown of the common positions:

  1. Clamping System (1st Letter): Indicates the method used to clamp the insert. Common examples include:

    • P: Lever lock
    • M: Wedge clamp
    • S: Screw clamping
    • C: Top clamping
    • D: Double clamping (lever and top)

  2. Insert Shape (2nd Letter): Corresponds to the first letter of the ISO designation of the insert it holds. Examples:

    • S: Square
    • T: Triangle
    • C: Rhombic (80°)  
    • D: Rhombic (55°)  
    • R: Round

  3. Holder Style (3rd Letter): Defines the tool style and approach angle. There are many variations, for example:

    • L: Turning towards the chuck (for external turning)
    • R: Turning away from the chuck (for external turning)
    • A, B, C...: Specific design variations related to approach angle and clearance.

  4. Insert Clearance Angle (4th Letter): Corresponds to the second letter of the ISO designation of the insert.  

    • N: 0° (Negative rake)
    • P: 11° (Positive rake)
    • D: 15° (Positive rake)
    • C: 7° (Positive rake)

  5. Shank Height (5th Number): Represents the height of the tool shank in millimeters. Common values are 16, 20, 25, etc.

  6. Shank Width (6th Number): Represents the width of the tool shank in millimeters, often the same as the height for square shanks.

  7. Holder Length (7th Letter): Indicates the overall length of the tool holder.

    • F, G, H, J, K, L, M...: Each letter corresponds to a specific length increment.

  8. Insert Size (8th Number): Corresponds to the first two digits of the insert's ISO designation, indicating the cutting edge length or inscribed circle diameter.

  9. Version/Modification (9th Letter - Optional): May indicate a specific version or modification of the tool holder design.

Example: PCLNR 2525 M 12

  • P: Lever lock clamping  
  • C: Rhombic 80° insert shape  
  • L: Turning towards the chuck
  • N: 0° insert clearance angle  
  • 25: 25 mm shank height  
  • 25: 25 mm shank width  
  • M: Holder length
  • 12: Insert size (related to cutting edge length)

2. Boring Tool Holders

The ISO nomenclature for boring tool holders shares similarities with turning tool holders but has some specific variations in the meaning of certain positions. A typical designation also consists of several letters and numbers.

  1. Type of Bar/Material (1st Letter): Indicates the material and construction of the boring bar.

    • S: Steel shank (solid)
    • A: Steel shank (with internal coolant)
    • C: Carbide shank

  2. Shank Diameter (2nd Number): Represents the diameter of the boring bar shank in millimeters.

  3. Bar Length (3rd Letter): Indicates the overall length of the boring bar. Similar to turning tool holders, letters denote different length increments.

  4. Insert Clamping Method (4th Letter): Similar to turning tool holders, indicating the clamping style (e.g., P, M, S).

  5. Insert Shape (5th Letter): Corresponds to the insert shape (e.g., S, T, C).

  6. Lead Angle of Boring Bar (6th Letter): Defines the approach angle of the cutting edge relative to the workpiece.

  7. Insert Clearance Angle (7th Letter): Corresponds to the insert clearance angle (e.g., N, P, D).

  8. Hand of Tool (8th Letter): Indicates whether the tool is right-hand (R), left-hand (L), or neutral (N).

  9. Insert Size/Cutting Edge Length (9th Number): Relates to the size and cutting edge length of the insert to be used.

Example: S 20 S - S C L N 16

  • S: Steel shank (solid)
  • 20: 20 mm shank diameter
  • S: Bar length
  • -: Often used as a separator
  • S: Screw clamping
  • C: Rhombic 80° insert shape  
  • L: Lead angle of the boring bar
  • N: 0° insert clearance angle  
  • 16: Insert size (related to cutting edge length)

3. Indexable Inserts

The ISO designation for indexable inserts is more detailed and typically consists of 9 or 10 positions, providing comprehensive information about the insert's geometry and characteristics.  

  1. Shape (1st Letter): Defines the basic shape of the insert.

    • S: Square (90°)
    • T: Triangle (60°)
    • C: Rhombic (80°)
    • D: Rhombic (55°)
    • R: Round
    • W: Trigon (80°)
    • V: Rhombic (35°)

  2. Clearance Angle (2nd Letter): Indicates the flank (relief) angle of the insert.

    • A: 3°
    • B: 5°
    • C: 7°
    • D: 15°
    • N: 0°

  3. Tolerance Class (3rd Letter): Specifies the dimensional tolerances of the insert.

    • A, B, C...: Each letter represents a different tolerance grade for dimensions like inscribed circle and thickness.  

  4. Type (4th Letter): Describes the presence and type of hole and chip breaker features.

    • N: Without hole, without chip grooves
    • M: With hole, with chip groove on one face
    • G: With hole, with chip groove on two faces

  5. Size (5th & 6th Characters - Numbers): Represents the inscribed circle diameter (IC) in inches, multiplied by 1/8". For example, "12" indicates an IC of 12/8" or 1.5 inches. For some shapes (like rectangles), it may indicate cutting edge length.

  6. Thickness (7th & 8th Characters - Numbers): Indicates the thickness of the insert in inches, multiplied by 1/16". For example, "04" indicates a thickness of 4/16" or 1/4 inch.

  7. Nose Radius (9th & 10th Characters - Numbers): Specifies the radius of the cutting edge nose in inches, multiplied by 1/64". For example, "04" indicates a nose radius of 4/64" or 1/16 inch (approximately 0.4 mm).

Example: CNMG 120408

  • C: Rhombic (80°) shape
  • N: 0° clearance angle  
  • M: With hole and chip groove on one face
  • G: Tolerance class
  • 12: Inscribed circle diameter (12/8" = 1.5 inches)
  • 04: Thickness (4/16" = 0.25 inches)
  • 08: Nose radius (8/64" = 1/8 inch ≈ 0.8 mm)

Understanding these ISO nomenclature systems is crucial for selecting the correct tooling for CNC turning and boring operations, ensuring proper fitment, geometry, and performance. Always refer to manufacturer catalogs for detailed explanations and specific variations in these coding systems.

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