The eccentric bush is the core of the BTA broaching system suitable for machine tools without the “Y” axis.
Thanks to the graduated scale engraved on its collar, it is possible to correct alignment errors which can be detected at the beginning of the machining.
Considering a 0,5 mm mis-alignment between the outside diameter and the internal one, alignment errors between +0,5 mm and -0,5 mm can be corrected.
Moving the tools by one notch, it is possible to move the insert of 0,03 mm.
The eccentric bush is made in hardened steel and it’s grinded. The outside diameter available are: B-32 / B-40 / B-50, with a H7 tolerance. On Customer’s request, VDI eccentric bush can be supplied. The eccentric bush is covered by patent.
To understand which BT/BTA system is suitable for a particular machining, it’s necessary to follow this procedure.
Let’s make the example of the machining of a 4 mm keyseat with a H7 tolerance.
> Identify the type of insert. L1=4 mm the item code is IN-4-H7
> Identify the type of holder: the item code is UT-4-32
> Identify the type of eccentric bush (for BTA systems): the item code is B-40