To perform high-speed and high-accuracy end milling and shorten preparatory time, it is important to consider tooling(tool holders).
BT shanks are widely used. Sometimes, HSK shanks (ISO standards) that can deal with high-accuracy machining with two-face contact clamping are used.
In Japan, ICTM standards HSK shanks are often used on multi-task machining centres. In ICTM standards, dimensions and tolerances of a spindle drive key and a tool holder key way were changed based on ISO standards, and the clearance between the spindle drive key and the tool holder key way are set at minimum to maintain high-accuracy cutting edge positioning. ICTM standard HSK shanks can maintain high-accuracy cutting edge height in turning. Therefore, there will be less unevenness of machined diameters. And it can reduce a possibility of leaving a lug at the centre of the workpiece when facing.
- Click on the links to learn more about the different shank types and tool holders!
"BT" stands for "Bottle grip taper".
A BT shank has an ATC arm and a pull stud. Each machine maker has it own pull stud geometry.
A pull stud is screwed into back end of a BT shank holder. When the holder is inserted into the spindle this pull stud is gripped and pulled upwards thus securely locating the holder.
"NT" stands for "National taper"
A NT shank has the same taper angle and dimensions as the BT shank.
It is installed on a machine by drawing a holder drawing thread using a draw bar of the machine.
"MT" stands for "Morse taper".
MT shanks offers superior centripetal force due to the use of a gentle taper angle.
There are tang-type Type 1 and drawing-thread type Type 2.
KSK Shank (ISO)
"HSK" stands for German "Hohle" (hollow) schaft (shank) kegel (cone).
This is a system to make the taper face and the machine´s end face stick together at one time (two-face holding system). This is done by shortening taper length, making the inside of the taper hollow, and elastically deforming the taper face outward by a force to pull the taper into the spindle. High centripetal force and effective in high-speed rotation work.
Taper collet chuck
End of 4D
- Taper is used for locating.
- High runout accuracy.
- Best for carbide end mills.
- Gripping forces are around 29Nm for ø6 and 69Nm for ø16.
- An end mill is put into a taper collet* (also referred to as spring collet) for installation.
End of 100 mm
A method to hold by elastically deforming a metal by using a needle roller. Also referred to as roll lock chuck. Gripping force is as high as 25Nm. An end mill is put into a straight collet* for installation.
Hydraulic chuck holder
End of 100 mm.
- A method to hold using hydraulic pressure.
- High runout accuracy.
- A very delicate chuck because a change in operating oil temperature, an operating oil leak or a thin inner wall of the holder shortens tool life.
Morse taper holder
End of 150 mm
A gentle taper angle. Therefore, if an end mill taper fits well the holder taper, the morse taper holder can achieve high accuracy with little runout.
Side lock holder
0.02 ~ 0.04 (mm)
End of 10
Generally, low tool runout accuracy. But some side lock holders have improved runout accuracy by considering the direction of lock bolts and machining eccentrically the inside diameter of the arbor.
Shrink fit holder
A method to attach and remove an end mill by heating and cooling the holder. Higher gripping force than a spring collet with the same holder diameter. High runout accuracy and rigidity. Can machine near a work piece wall due to slim shape. Used for deep milling of moulds with a small-diameter end mill.