Just like the 8EX rotor milling machine delivered in late 2013, this latest model from Holroyd Precision will be used to rough mill and finish-machine stainless steel rotors from blanks of up to 850 mm in diameter and 4,500 mm in length.
Manufactured from steel grades such as 1CR13 (UK: 410S21 stainless), rotors produced on the 8EX machine will weigh as much as 8.2 tonnes. Applications will include natural gas transportation, organic rankine cycle expansion generators and process industry compressors.
The ‘standard’ EX range begins with the 1EX – a machine capable of milling helical components of as little as 150 mm – and offers stepped increases in capability, right up to the 8EX, an 850 mm OD rotor miller. A ‘special order’ 10EX machine is also available for components exceeding one metre OD. In addition, various bespoke EX models are available.
Holroyd EX Series milling machines are designed with the ability to maximise the high surface speeds demanded by the very latest cutting technologies. Surface speeds in excess of 200 m/min, for example, are often used when cutting the rotor profile forms in a single pass to leave only the allowance of 0.3 mm stock for the finishing operation.
EX machines cut a full-depth groove by traversing the cutting tool through the material at the relevant helix angle, whilst at the same time rotating the component in the ‘C’ axis. Accurate synchronisation between the axes is maintained via CNC, with digital drive technology controlling all axis movements. The cutting head is able to remove so much material in one step because the majority of heat generated is transferred to the swarf chips. These are then removed from inside the machine by means of a conveyor system.
