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The importance of clamping accuracy and repeatability is almost second only to handle accuracy or dynamic balance. Tool holder clamping accuracy refers to the deflection of the tool holder after clamping the tool. The measurement method is to rotate the test rod by 360 degrees at a position several times the length of the shank diameter after clamping the test rod and measure its deflection. As shown in the figure, the tool holder clamps the test rod and fixes it on the measuring tool. Using point A as the reference point, rotate 360 degrees to measure the deflection at point B or point C. The distance between the nose of the tool holder (point B) and point C is expressed as several times the tool holder diameter (assuming that the tool holder diameter O d is 6mm, and the 4 times length/4d is 24mm). The repeatability of the tool holder refers to the change in the clamping accuracy of each measurement under the condition of repeated disassembly or clamping of the tool holder. The longer the distance between point C, the more difficult it is to maintain the clamping accuracy and repeatability.

The clamping force of the tool holder refers to the clamping force of the tool holder to the tool, and its size can be measured in Nm Newton meters with a measuring tool. The higher the clamping force, the more tightly the tool holder can hold the tool, and the better rigidity makes it difficult for the tool to slip or loose when the cutting conditions are more severe, resulting in a situation commonly known as "tool drop". In other words, according to the different cutting conditions, a tool holder with sufficient clamping force should be selected to ensure the processing quality and the life of the tool and the machine spindle.

Shank accuracy refers to the close tolerance of the shank of the tool holder and the inner hole of the spindle. This tolerance level is divided into 12 levels from AT 1 to AT 12. The higher the shank tolerance level, the closer the shank of the tool holder is to the inner hole of the spindle. For example, AT3, which has an area of 85%, is better than AT4. According to the standard recommendation of ISO1947, AT3 is the most basic requirement for the shank of a tool holder.

The selection of the material used to manufacture the knife handle is also important to the life and stability of the knife handle itself. The material of the shank is relatively low in importance to the accuracy or other characteristics of the shank, but is a high-grade material. In addition to better tensile strength and toughness, its molecular structure is finer and dense. High-quality materials and correct material handling can extend the service life of the tool holder without changing its accuracy, so that it will not become a "consumable".

Without the right heat treatment method, no matter how high-grade materials and processing equipment are, it is impossible to achieve a tool holder with high precision and long life. The correct and excellent heat treatment can heat the material and rapidly quench it to obtain a high proportion of Asada loose iron, with excellent mechanical properties, including hardness, structure density, wear resistance, flexural strength, and tensile strength. On the contrary, the wrong or bad heat treatment caused the material itself to loose structure, uneven hardness, excessive residual internal stress, excessive residual austenitic iron, abnormal grain size and structure density, resulting in the mechanical properties not reaching the expected performance or even the material Phenomena such as deformation and cracking affect the most important accuracy and life of the tool holder.

The clamping force of the tool holder refers to the clamping force of the tool holder to the tool, and its size can be measured in Nm Newton meters with a measuring tool. The higher the clamping force, the more tightly the tool holder can hold the tool, and the better rigidity makes it difficult for the tool to slip or loose when the cutting conditions are more severe, resulting in a situation commonly known as "tool drop". In other words, according to the different cutting conditions, a tool holder with sufficient clamping force should be selected to ensure the processing quality and the life of the tool and the machine spindle.