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Understanding the ISO Code System for Turning Inserts: A Comprehensive Guide


All turning inserts have a unique ISO code that contains various letters and numbers – believe it or not, these actually mean something! From just looking at the ISO code you can figure out the insert’s shape, relief angle, tolerance, cross-section type, cutting-edge length, thickness, radius, and chip breaker!

In this blog, we will discuss how to identify all these key dimensions, so you will never need to check for part numbers again.

Below is an example of the turning insert code that will be referenced throughout.


1. Insert Shape

The shape of a turning insert is determined by the 1st part of the ISO code.

Choosing the right insert shape for your turning tool is essential. The shape of the insert can affect the vibration during operation, the ability to turn complex contours, the strength of the insert and its ability to take bigger and heavier cuts.

See below the shape options for Turning Inserts and how they correlate to the ISO code.


2. Relief Angle

Section 2 of the milling insert ISO code refers to the relief angle of the insert.

The relief angle for a milling insert is of paramount importance in achieving efficient and successful machining operations.

It plays a crucial role in chip formation, tool life, cutting forces, and surface finish. Understanding the influence of the relief angle and selecting the appropriate one can greatly enhance machining performance, productivity, and the quality of the finished product.


3. Tolerance

The tolerance of a turning insert is determined by the 3rd part of the ISO code.

Tolerance dimensions are indicated by a letter ranging from A - U. Dimension A relates to the inscribed circle (IC), dimension B relates to the insert height (for pentagon, triangle, and trigon shapes – for other polygons, the dimension B relates to the distance that is measured along the bisector of the corner angle) and dimension T relates to the thickness of the insert.

See below the options for the tolerance and how this correlates to the ISO code.


4. Cross-Section Type

The cross-section type of a turning insert is determined by the 4th part of the ISO code.

The cross-section highlights the differences in the design of the insert, such as the fixing holes, countersinks, and special features. This dictates what clamping method would be used to fix the insert on to the tool holder. 

See below the options for the cross-section type and how this correlates to the ISO code


5. Cutting Edge Length / Diameter IC

The cutting-edge length of a turning insert is determined by the 5th part of the ISO code.

It is a 2-digit number that generally indicates the width or length, however this is only applicable to insert shapes with no IC (inscribed circle), such as rectangular and parallelograms.

For insert shapes such as round, square, triangle & trigon, this would then indicate the diameter of the inscribed circle (IC).

See below the options for the cutting-edge length / diameter IC and how this correlates to the ISO code


6. Thickness

The thickness of a turning insert is determined by the 6th part of the ISO code.

The thickness of a turning insert is measured from the bottom of the insert to the top of the cutting edge. This will be shown as a 2-digit number except where the insert features a T and then a single digit number eg T3. This is due to the fact that there are more than one increment within each mm. eg 03 is 3.18mm whereas T3 is thickest at 3.97mm.

See below the options for the turning insert thickness and how it correlates to the ISO code.


7. Nose Radius

The nose radius of a turning insert is determined by the 7th part of the ISO code.

The nose radius of an insert can affect the performance. A larger nose radius can result in the use of higher feed rates, and larger depths of cut, and they can handle more pressure, making them much better for heavier metal removal. Whereas a turning insert with a smaller nose radius can only take smaller depths of cut, they also have weaker cutting edges, and they can only handle a small amount of vibration but are much better for finishing as they are sharper and have less surface contact.

See below the options for the turning insert nose radius and how this correlates with the ISO code.


8. Chip Breaker

The Chip Breaker of the turning insert is determined by the 8th position in the ISO code.

The chip breaker is represented as 2 letters in the ISO code. The chip breaker affects the cutting resistance, if the cutting resistance is low, it can avoid chipping and fracturing of the cutting edges. Reduced cutting resistance can also decrease the tool load and heat built up. The chip breaker also determines the depth of cut the insert can take, if you are not applying the correct depth of cut then you won’t be activating the chip breaker, this can cause the swarf to build up and become stringy, some people refer to this as a bird’s nest.

Some of the below chipbreakers are available on both negative and positive inserts but the min-max depths of cut may vary.

See below the options for different chip breakers and how this correlates with the ISO code.

Korloy:

YG-1:


How do I calculate feed rate from mm per rev?

To find the Surface Speed from RPM, we need to follow the equation example below.

 

IMAGE IS MISSING IN ORIGINAL BLOG


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