Boring bars for finishing
cutting conditions
These bars are designed for fine boring in accuracy IT7 to IT8 of roughly pre-machined bore. Roughness from Ra 1,6 to 2,7
Cutting speed
Because the cutting blade seat is according to ISO, it is possible to use the cutting blade from any producer. The cutting speed is set in accordance to producer's recommendation however the cutting blade must have a proper chip former to ctreate formed chip.
Cutting depth ae
We recommend from 1 to 1,5 x radius of a cutting blade tip.
Feeding
| Blade tip radius [mm] |
Feeding fz [mm] |
| 0,1 | 0,02 - 0,05 |
| 0,2 | 0,04 - 0,08 |
| 0,4 | 0,10 - 0,16 |
The feed rate coordinated together with cutting blade tip radius determining roughness Ra. We recommend the first choice from the chart. The slenderness of bar and increasing revolutions can cause vibrations and worsening Ra.
Cooling
Cooling has a good effect on cylindricity achievement. Decrease of temperature dilatation. Air cooling is recommended when machining hardened steel with CBN cutter.
Boring bar setting
For rough dimension adjustment slacken the screw and by turning the nut with degree scale is the cutter ejected to an approximate dimension (approx. for 0,1mm minus). After adjusting tighten the screw. The cutting needs to be started by machining fine chips in the bored hole. According to measured dimension is the cutting unit set as follows:
- When over-measure is more than 0, 3 mm set rough adjustment again.
- When over measure is less than 0, 3 mm the screw should be slackened for approx. 90°. By turning the nut with degree scale for corresponding divisions (1 division= 0,02mm/ø) is the cutter set to dimension. When the real dimension is measured the cutter is set to the needed dimension by turning the nut with degree scale.
WARNING! The screw should not be tightened!
Notice: the screw should not be slackened more than 120° to keep rigidity of the cutter unit.