Steep taper JIS (MAS 403) BT30/BT40/BT50
The spindle interface JIS B 6339-2 as the traditional interface for milling spindles distinguishes itself through it robust design. Its field of application ranges from fine machining to heavy duty roughing. The tool holder is pulled in the milling spindle with the help of an additional pull stud. The centering takes place via the taper contact. Therefore, the JIS B 6339-2 interface is primarily suitable for applications with a spindle speed of up to 12,000 rpm.
Technical specifications JIS B 6339-2
Steep taper BT30
- Tool holders case-hardened 60 – 2 HRC
- Tensile strength in the core at least 950 N/mm2
- Taper in tolerance quality AT3
- Angle of cone: 8° 17'50'' +4''
- Without bore for data chip
- Form JD: interior coolant supply through centre
| BT30 | D1 | D2 | D3 | D4 | L1 | L2 | L3 | T | B1 | B2 |
| [mm] | 31,75 | 12,5 | 46 | 42 | 48,4 | 22 | 13,6 | M12 | 16,1 | 16,3 |
Steep taper BT40
- Tool holders case-hardened 60 – 2 HRC
- Tensile strength in the core at least 950 N/mm2
- Taper in tolerance quality AT3
- Angle of cone: 8° 17'50'' +4''
- Without bore for data chip
- Form JD/JF: interior coolant supply through centre (form JD) and through the collar (form JF)
| BT40 | D1 | D2 | D3 | D4 | L1 | L2 | L3 | T | B1 | B2 |
| [mm] | 44,45 | 17 | 63 | 59 | 65,4 | 27 | 16,6 | M16 | 16,1 | 22,6 |
Steep taper BT50
- Tool holders case-hardened 60 – 2 HRC
- Tensile strength in the core at least 950 N/mm2
- Taper in tolerance quality AT3
- Angle of cone: 8° 17'50'' +4''
- Without bore for data chip
- Form JD/JF: interior coolant supply through centre (form JD) and through the collar (form JF)
| BT50 | D1 | D2 | D3 | D4 | L1 | L2 | L3 | T | B1 | B2 |
| [mm] | 69,85 | 25 | 100 | 95,5 | 101,8 | 38 | 23,2 | M24 | 25,7 | 35,4 |
Coolant supply JIS B 6339-2
According to JIS B 6339-2, 3 possibilities of inner coolant supply are available:
- Form J: No inner coolant supply
- Form JD: Central coolant supply through retention knob. A retention knob with centralized bore is required.
- Form JF: Lateral coolant supply via the collar. A sealed retention knob is required.
Haimer clamping devices with taper according to DIN 6339-2 are performed in form JD/JF unless otherwise noted.
Form JD/JF means: The clamping devices are equipped with bores for form JD as well as for form JF. Unless otherwise stipulated, the tool holders are delivered in form JD. The bores at the collar for form JF are then sealed with plastic-dowels and secured with lock screws.
For changing to form JF, the bores at the collar must be opened by unscrewing the lock screw halfway. Extraction of screws together with thedowels by using pliers.
The bores also can be sealed again. A conversion kit consisting of dowels and lock screws is available.
Attention: Each dowel for single use only!
