Why An HSK Tool Holder Is Better Than A Conventional One?

If tool cutters in a wood or metal milling facility carry out the actual cutting and chiselling activity, the devices that hold the tools firmly and provide stability to them during the machining process are no less important. These devices aka tool holders made of aluminium or steel mostly taper at one end and appear to be conical in their looks and design. The typical design ensures the taper or the male part of the tool holder snugly fits into the female or the receiver part of the cutting spindle. The spindle on its part leads up to the gearbox of the cutting implement and rotates at varying speeds depending on the type of material to be cut and the level of cutting. These implements such as the HSK tool holder and others are important to prevent any loss of efficiency or possible deflection when the spindle rotates.

Choosing the right tool holder is important as the result of the cutting process depends on it. Thus, should the tool holder is not of the right shape and size, it will not be able to hold the tool and machine spindle firmly leading to an imperfect cutting output. Needless to say that imperfect cut tools adversely impact the quality of downstream products in terms of poor material finish.

Benefits of a tool holder

· Provides a gripping force on the tool even when it is subjected to cutting at high speeds

· Can be secured onto a bench, tool trolley or a CNC machine thus making it immobile

· Reduces vibrations and ensures a high cutting accuracy

· Enhances the longevity of tool, reduces noise during cutting, and decreases the chances of causing damage to the spindle

· Maintains the linear actuation of the cutting machine

· Improves quality and productivity

Parts of a tool holder

A typical tool holder or an HSK tool vice comprises of three parts namely, the actual tool holder body, collet and collet nut. In case of other tool holders such as ISO, SK, and BT, there is an additional retention knob as well.

Types of tool holders

Although there are different types of tool holders namely ISO, CAT, SK and BT, it is the HSK that has found favour and acceptance in the industry, be it related to CNC machines or the conventional one. This is not to suggest that the traditional steep taper tools like the ones mentioned above have fallen by the wayside. In fact, in places like the United States, there is still some resistance to the acceptance of HSK type tool holder and the traditional one remains the preferred tooling interface.

Why HSK?

The German abbreviation of HSK stands for a ‘hollow taper shank’ and has been developed to address the performance issues associated with high speed machining, which traditional ones do not handle properly. The HSK technology came into being after a research of five years carried out by stakeholders comprising of academics, members from the industry, end users, and standard organizations.

The research team has created standards for such tools ranging from A to F, wherein type A and C are for cutting applications that need moderate torque and a similar spindle speed. Whereas, types E and F have come to the aid of applications that require a low torque but a high spindle speed. Similarly, type B & D are to help applications with a high torque and a moderate to high spindle speed.

HSK and conventional tapers

When we compare an HSK shank with a conventional one the first category is of radial and axial stiffness, arguably the most important aspect of machining. Here, since the HSK shank is hollow and the clamping mechanism operates from inside, the holding of the tool and spindle is more secured. Moreover, an HSK tool vice has a segmented collet that expands radially upon the application of drawbar pressure. So, instead of breaking down or causing deformation, the collet holds against the inner walls of the shank.

The HSK tapers have some added advantages in terms of preventing tool collisions and related machine downtime and maintenance. When the spindle speed is greater than 8000rpm the rate of expansion between the spindle receiver and tool holder shank remains uneven. This is where an HSK taper with its hollow design helps by breaking off and thereby protecting the spindle.

Conclusion

The use of tool holders in a machining arrangement is important from the point of providing stability. And HSK tool holders are better placed than conventional ones in addressing the same.