Currently in build at PTG Holroyd’s Rochdale-based machine tool technology centre, the machine, a PTG-Holroyd 4EX-R-BL (BL = blower) model, will be used to precision-mill both helical rotors and Roots-type blower air ends. In doing so, it will equip the German manufacturer with exceptional levels of speed, flexibility and efficiency.
Transforming the manufacture of straight-fluted rotors
“We have long been aware of a gap in the market for a rotor milling machine that can fulfil the needs of manufacturers who wish to produce both traditional compressor rotors and low-pressure output displacement compressors, such as Roots-type, rotary lobe blowers,” said PTG Holroyd sales director, Mark Curran.
“It is for that reason we developed the 4EX-R-BL – a machine tool that applies the high speed, precision and performance of PTG Holroyd EX Series milling machines to the production of Roots-type blowers. Fully appreciating the attributes of the 4EX-R-BL, our German customer believes the machine will transform the way in which their straight fluted, infinitive lead rotors are milled, significantly reducing manufacturing time and increasing the accuracy of the production process.”
Incorporating Siemens’ Sinumerik ONE CNC
In line with PTG Holroyd’s objective of simplifying the production of even the most complex of helical components, the company’s new 4EX-R-BL model utilises Siemens’ Sinumerik ONE future-proof CNC. PTG Holroyd is believed to be the first UK manufacturer to offer the Sinumerik ONE control with its machine tool technologies and, only last year, chose the automation system for its new range of HG Series gear and rotor grinding machines.
“We selected the Sinumerik ONE CNC for its ease of use, ability to accommodate each customer’s Industry 4.0 strategy, rich, real-time reporting of machine health and performance data, and uncompromising levels of industrial security,” added Curran.
“We also embraced the ‘Create my virtual machine’ and ‘Run my virtual machine’ capabilities of the Sinumerik ONE software suite, in order to build and run a virtual ‘digital twin’ of the 4EX-R-BL on the desktop. This proved invaluable throughout the development stages of the new machine.”
30-minute milling time, floor-to-floor
Although sitting within PTG Holroyd’s EX range of rotor milling machines, the 4EX-R-BL is a totally new concept that has been designed from the ground up.
Equipped to mill helical rotors of up to 450mm in diameter, the 4EX-R-BL will also rough mill blower blanks of around 320mm in diameter and 900mm body length, into straight fluted rotors in 30 minutes floor-to-floor, ready for finish profile milling to absolute size.
This represents a significant time saving when compared to the one-and-a-half to two hours typically required to cut individual Roots-type blower rotor flutes using traditional milling techniques.
