A machining spindle unit that can change up to four tools automatically within a production cycle has expanded the number of tools carried on a 12 station rotary transfer machine.

By developing a machining spindle unit with the flexibility to change up to four tools automatically within a production cycle, Mikron Machining Technology of Agno, Switzerland, has expanded the number of tools carried on its latest 12 station Mikron NRG-50, claimed to be one of the most advanced rotary transfer machines in the world. As a result the capability of the machine, which can perform both high volume and medium batch production involving up to five-axis simultaneous machining, deep hole drilling, milling, turning and even assembly cycles. It has up to 30 tools available as standard that can be applied to produce features on all six faces of a component in a single cycle.

With the ability to toolchange, the new unit head can now carry sister tooling to extend uninterrupted production, additional tools to produce complex features of a component or provide a quick-changeover solution, for instance to support family of parts production.

The innovative development by Mikron Machining Technology's engineers enables up to four tools to be carried around the spindle of the unit head.

The spindle has through tool coolant supply at up to 80 bar and an integrated air blast to clear the HSK 40-F taper shank of swarf or debris during the tool change.

Rapid tapping can also be programmed from the CNC control of the machine.

The stroke of the unit head is 70mm, the maximum spindle speed 10,500 rev/min and spindle torque is 0.9Nm.

The unit can be mounted in any position around the rotary table of the machine in the vertical plane, above or below the table, or horizontally.

And such is the power of the CNC control that up to 22 automatic toolchange units - each holding four tools, can be accommodated on the 12 stations of the machine.

In comparison with other indexing toolhead designs that usually utilise a 'revolver' style unit the Mikron system provides high stability due to a greater length of bearing support and therefore tool life and accuracy is improved and machining consistency more apparent.

To perform the toolchange which is a simple operation under CNC control taking just 2.5s chip to chip, the spindle stops and the unit head withdraws.

Using a hydraulic release, the magazine unit indexes 90 deg and the unit feeds forward to simply pick up on the taper of the new tool ready for production to continue.