In the world of CNC machining, turning inserts play a crucial role in shaping and finishing materials with precision. The International Organization for Standardization (ISO) and ANSI (American National Standards Institute) provides ISO and ANSI turning insert nomenclature standards, ensuring consistency and quality across the industry. This classifications includes various notations that describe the key characteristics of turning inserts, such as their shape, relief angle, tolerance, cross-section type, cutting edge length, thickness, nose radius, and chip breaker features. These notations can typically be found in product catalogs, technical data sheets, and online resources provided by tool manufacturers.
Example of ISO Code: Example of ANSI code:
CNMG 120408-HR4 CNMG 432-HR4
The shape of the turning insert is denoted by the first letter in the ISO/ANSI code. Each shape is designed for specific machining tasks and determines the insert's strength and versatility. Common shapes include:
C (Rhombic, 80°)
D (Rhombic, 55°)
V (Rhombic, 35°)
S (Square, 90°)
T (Triangular, 60°)
W (Trigon, 80° Equivalent)
R (Round, 360°)
The relief angle is indicated by the second letter in the ISO/ANSI code. It defines the angle between the insert's cutting edge and the workpiece, affecting the insert's cutting performance and chip flow. Common relief angles include:
1. (N) Negative Inserts
Inserts with a zero clearance angle (symbol “N”).
Key Features:
Applications:
First choice for roughing and general machining.
2. Positive Inserts
Inserts with any non-zero clearance angle (symbol: “A” = 3°; “B” = 5°, “C” = 7°; “D” = 15°, “E” = 20°, “F” = 25°, “G” = 30°, “P” = 11°)
Key Features:
Advantages:
Applications:
Tolerance is represented by the third letter in the ISO code and specifies the allowable deviation from the nominal dimensions of the insert. Tighter tolerances ensure higher precision and better surface finishes. Common tolerances include:
The all specify the following allowances:
The cross-section type is indicated by the fourth letter in the ISO/ANSI codes and simultaneously describes two non directly connected parameters of the insert: 1. Mounting Method: Describes how the insert is clamped onto the toolholder and 2. Chipbreaker: Indicates the presence and position of the chipbreaker on the insert. It does not define the geometry of chip breaker, though.
Code - Chipbreaker Placement - Insert Type
The cutting edge length (ISO) or diameter IC (ANSI) is represented by a number following the cross-section type. This measurement indicates the size of the insert and is crucial for ensuring compatibility with the tool holder and the workpiece. For example:
In our example – 12 / 4: Indicates a 12mm cutting edge length /or 12.7 diameter IC.
The thickness of the turning insert is denoted by a two-digit number following the cutting edge length. This measurement, in millimeters, affects the insert's durability and ability to withstand cutting forces. For example:
In our example – 04 / 3: Indicates a thickness of 4.76mm / 0.1875”.
The nose radius is indicated by a number following the thickness. This measurement defines the radius of the insert's tip and influences the surface finish and cutting stability. For example:
In our example – 08 / 2 : Indicates a nose radius of 0.8mm / 0.0313“.
The chip breaker is represented by additional letters or symbols at the end of the code. It describes the design features that help break the chips into manageable pieces, improving chip control and reducing heat buildup during machining. Each manufacturer develops their own chip breakes and their codes, but chip breaker designs can be specified as:
In summary, understanding of turning insert codes allows machinists to select the appropriate insert for their specific machining needs. By considering the insert's shape, relief angle, tolerance, cross-section type, cutting edge length, thickness, nose radius, and chip breaker features, machinists can achieve optimal performance, precision, and efficiency in their operations.
