How much do you know about tool shank and how to choose BT/HSK/CAPTO tool shanks?

The tool shank is a tool that connects the cutting tool to the machine tool. Plays the role of an interface between cutting tool and machine tool.

The performance of the tool shank directly affects the machining accuracy. In order to fully demonstrate the performance of machine tool and cutting tool, the tool shank must have run out accuracy, stiffness (deformation resistance), and high clamping force. Even if the spindle rotates at high speed, the tool shank must meet these requirements without being affected by centrifugal force or other external forces. Bounce accuracy is a measure of the degree to which a tool rotates away from its central axis. The higher the jumping accuracy, the smaller the tool shake and the higher the machining accuracy.

The tool shank is defined by standards based on shape and size. Machining centers include BT, HSK, etc., while lathes, turning centers, and lathe based multitasking machines have CAPTO.

BT:

BT stands for "Morse taper" and is marked with a tapered tool shank. It is used by connecting it to the spindle of the machining center. The BT knife tool shank was initially developed in Japan and widely used in manufacturing sites around the world.

The size of the taper is fixed, with a 7/24 taper, where the diameter is 7mm smaller in the axial direction at 24mm. According to the maximum diameter length of the taper, there are nominal numbers such as BT30, BT40, and BT50.

SET BT tool shank quick change adopts a 7:24 taper (ISO 7388 standard), which is a universal design for traditional machine tools. By mechanically locking with rivets and using spring clamps or hydraulic clamping systems, rapid tool changes can be achieved. Compatible with most traditional Japanese/Taiwanese machining centers (such as Fanuc, Mazak systems). It has the advantages of low cost, high market penetration, and simple maintenance. Suitable for medium and low-speed machining (≤ 12000 rpm). High standardization and easy access to accessories.

HSK:

HSK is a tool shank standard developed in Germany for high-speed rotation. HSK stands for "Hohlsch ä fte Kegel" in German, which means hollow rod cone tool shank.

The HSK tool shank has a short overall support length and a hollow internal structure, which is lightweight to support high-speed spindle rotation. The size of the taper is fixed and adopts a 1/10 taper, where the diameter is 1mm shorter than 10mm in the axial direction. Due to the dual contact system of the conical component and the end face of the tool shank in close contact with the spindle, it provides high stiffness. The size of the tool shank is also specified, and SET HSK tool shank quick change has five sizes: 40, 50, 63, 80, and 100. The smaller the number, the smaller the tool shank size. SET HSK tool shank quick change adopts a 1:10 hollow short cone (DIN 69893/ISO 12164) with double-sided contact design. The conical surface and end face are synchronously locked, and centrifugal force is used to enhance the clamping force. Specially designed for high-speed machining centers (German/European machine tools such as DMG, Hermle). Strong high-speed stability (supporting 30000+rpm) and outstanding resistance to centrifugal deformation. High repeatability accuracy (up to ± 0.002mm). High rigidity, suitable for high-precision milling and hard material processing.

CAPTO:

Due to the traditional 7:24 taper BT tool system being unsuitable for high-speed machining, its inherent defect of single-sided contact positioning cannot guarantee various performance indicators during high-speed machining. Instead, double-sided positioning tool shanks represented by HSK and Capto have been used. The unique structure of the Capto tool shank gives it reliable positioning accuracy and high contact stiffness, making it widely applicable in industries such as machinery, electronics, automotive, and aviation.

The quick change torque transmission ability of the SET CAPTO tool shank is extremely strong (more than 30% higher than HSK), and the anti torsional vibration performance is excellent. Fully symmetrical design, suitable for multi-directional cutting (with obvious advantages in five axis machining). Modular scalability is strong, and multiple levels of extension rods can be connected in series.