Roots-Type Blower Milling Machines

A revolutionary new manufacturing technology from PTG Holroyd, the 4EX-R-BL is really two machines in one.

In addition to producing helical rotors, 4EX-R-BL models can also be programmed to mill straight-fluted, ‘infinite’ lead rotors, as used in Roots-type blower ‘air ends’.

30-minute milling time, floor-to-floor

Equipped to mill helical rotors of up to 450 mm in diameter in one seamless manufacturing process, the 4EX-R-BL will rough mill blower blanks of around 320 mm in diameter and 900 mm body length into straight-fluted rotors. The process takes approximately 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 flat bed milling techniques, where each flute has to be manually turned then milled in a separate operation.

key features


  • Produces all helixes from horizontal to vertical
  • Significantly reduced manufacturing time and increased accuracy
  • Mills helical rotors, infinitive lead blowers, helical blowers, compressor rotors and vacuum pumps
  • Ideal for manufacturers who require considerable flexibility in their production strategies
  • Fully automated process able to machine two- and three-flute blowers in one sequence
  • No manual intervention or indexing during the milling process
  • Bespoke steadying system designed to withstand the additional forces of milling straight flutes
  • Automatic rotation and positioning ready for milling of the next flute


additional information

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