What is the difference between BT toolholder and JT toolholder?
December 28, 2021
1. Manufacturing standard: BT handle is Japanese standard mas-403, and JT handle is German standard din69871.
There is also a manufacturing standard jisb6339 for BT tool handle. Although the Japanese standard jisb6339 has replaced the standard mas-403 of Japan working machinery industry association, because its main overall dimensions are the same, it basically has no impact on the use. Therefore, many tool manufacturers still mark the mas-403 standard code on their samples instead of jisb6339. However, it should be noted that the pull nails used in the two standards are different.
2. The clamping part of the manipulator is different from the pull nail. The flange of BT tool handle is thick. The clamping groove of the manipulator is close to the side of the tool. The depth of the keyways at the two ends is the same and does not milling through; The JT tool handle flange has a small thickness and a positioning notch for tool installation. The depth of the two end keyways is different and milled through.
Most JT handles have internal cooling channels to support internal cooling in the center of the spindle or (and) in the end face of the spindle. The main structure is shown in the figure below. BT handle is a Japanese standard. The shoulder size is larger than JT, so the knife weight is increased. There is positioning on the 180 degree circumference, and there is no positioning notch unfavorable to dynamic balance. Most BT handles do not have internal cooling channels, and some BT handles with internal cooling channels can be provided. However, due to the thin neck of the pull pin of the BT handle (especially BT40 and below), increasing the cooling channel in the center may lead to the risk of the pull pin being broken and the tool handle falling off. The main structure is shown in the figure below. There is little difference in principle. But the actual use must be distinguished and can not be mistaken.
BT's machine tool cannot use JT's handle, and JT's machine tool cannot use BT's handle. Most standard configurations of European machine tools are JT, such as din69871. Most JTS in Europe can choose to have central internal cooling or spindle end face internal cooling. Most machine tools in Japan, South Korea and Taiwan are equipped with BT as standard. BT handle may be thin due to the neck of the pull nail, and most of them do not have internal cooling. Because the cross-sectional area of the pull nail may be too small and the strength will not be enough if the internal cooling hole is added.
Let's look at commonality:
1) At present, din69871 (i.e. JT) and masbt are the most used tool handles in China;
2) Din69871 type tool handle can also be installed on ANSI / ASME spindle taper hole machine tools;
3) The tool handle of international standard is07388 / 1 can also be installed on din69871 and ANSI / ASME spindle taper hole machine tools. Therefore, in terms of universality, is07388 / 1 tool handle is the best.