Adaptors

The mounting of cutting tools generally occurs on tool tapers and holders either mechanically, hydraulically, or with thermal fitting. The significance of the tool holder in machining greatly affects the reliability of the machining process and the lifespan of the tool. Even a good tool will not perform well with a poor holder, so holders must always be chosen based on the requirements of the tool and the machining method. Using the right and suitable tool holder also saves on tool costs.

The selection of the right tool holder is influenced by factors such as the machining operation, the tool to be mounted, the reach of the holder, the holder's rotational accuracy, and its balance. Tool holders are attached to machining centers with various tool tapers like Capto, which is common in multi-tasking lathes equipped with a B-axis, HSK, which is prevalent at high spindle speeds, and SK and BT tool tapers that are common in vertical and horizontal machining centers, SK DIN2080, which is common in manual milling machines, and Morse taper, which is common in column and radial drilling machines. Machining centers also offer various angle heads with fixed or adjustable angles, for example, for drilling angled holes, and speed increasers, which allow the use of small carbide cutting tools on machines where the spindle's own speed range is insufficient to achieve the required cutting values of the tool.

Generally, tool mounting to the tool taper happens mechanically, for instance, using various tightening collets like ER collets or using a side-mounted tightening screw for the Weldon or Whistle Notch flat of the tool. Modern tools require precise rotational accuracy and strong holding power to function, which is achievable with hydraulic holders. The long and slender structure of the tool holder aids in tool reach even in tight spaces such as multi-axis machining, making thermal shrink fit chucks popular as tool holders in small and high-speed multi-axis machines.

For mounting indexable face mills and slotting cutters, face mill arbor or combination mill arbor holders are available, where the tool is locked with a mounting screw from the end face of the tool taper.

When using a traditional long tool holder, vibration issues and instability in the machining process are often encountered. Tool manufacturers have developed specially vibration-damped tool holders for long reaches, whose internal structure reduces the frequency of vibration, stopping the tool vibration.

On lathes, tools are mounted to either static and rotating holders with bolt-on BMT mounting or VDI mounting. In modern multi-tasking lathes, the typical tool mounting tapers for the tool spindle are Capto and HSK tool tapers, with the Capto system being the most established mounting system due to its extensive range of tool holder options, especially for turning tools. Rotating tools in lathes are typically mounted using ER tightening collets, but various manufacturers offer different quick-change systems such as the modular MTSK quick-change system by Italian M.T. S.r.l.. For lathes equipped with traditional tool turrets, various special holders are available such as adjustable angle heads for drilling angled holes, hobbing tool holders for gear manufacturing, or reciprocating holders that convert rotary motion into linear motion, enabling the broaching of keyways.