Eighteenth Holroyd ultra-high prerformance rotor milling centre for global air compressor manufacturer

A globally leading air compressor manufacturer has ordered its 18th PTG Holroyd EX Series CNC helical rotor milling production centre. Currently in build at PTG Holroyd’s UK-based manufacturing facility, the machine - a 3EX-R-XL derivative - will be installed at one of the air compressor specialist’s overseas facilities early next year.

Designed to rough mill rotor blanks of up to 350 mm in diameter, the 3EX-R-XL will be used to produce rotors for portable and stationary air compressors. With its ‘XL’ (extra component length) capability, something that is a new ‘as standard’ feature across PTG Holroyd’s entire EX Series, the machine will feature a much longer machine bed than earlier models. This will equip it with the flexibility to accommodate longer helical components when required. 

More than 30 machines sold to this customer
“If repeat orders are a sign of the faith a company places in a supplier and its technologies, this latest order is a considerable honour for our business,” comments PTG Holroyd Sales Director, Mark Curran. “Although this will be the 18th Holroyd EX machine purchased by the customer, over the years they have bought more than 30 of our advanced machine tool technologies. Models sold to them include EX Series machines, CS Series cutter sharpener machines, and TF Series test fixture machines which are used to ensure the accurate measuring of rotor profile clearances.”

PTG Holroyd’s ultra-high-performance EX Series CNC helical rotor and pump-screw production centres have earned global acclaim for their high speed, high precision and high efficiency, as well as for their 

build quality and enduring reliability. Regularly updated to offer the most advanced production capabilities, the EX-R-XL range begins with the 2EX-R-XL – a machine capable of milling helical components of up to 250 mm in diameter – and offers stepped increases in capability, right up to the 8EX-R-XL (850 mm maximum component diameter) rotor milling production centre. A dual-capability 4EX-R-BL helical rotor and Roots-type blower machine for rough and finish-milling helical rotors and blower blanks of up to 450 mm in diameter and 1960 mm in length is also offered, as is a ‘custom-build’ 10EX-R-XL machine for milling rotor blanks in excess of 1000 mm in diameter. All models benefit from the integrated safety, security, reliability and reporting that comes through the use of Siemens SINUMERIK ONE CNC.

Delivering high accuracy and aggressive stock removal rates, all PTG Holroyd EX-R-XL models can reduce overall machining times significantly, thanks to their ability to both rough and finish-mill components. Accurately rough-milling components ensures minimal stock removal during finishing processes, resulting in reduced cycle times and improved component quality. This is due to minimal heat being transferred to the component during finish milling and is the result of the cutting head’s ability to remove so much material during roughing, when the majority of heat generated is transferred to the swarf chips. 

EX Series rotor production centres 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. Developed to improve productivity through a combination of high-speed operation, menu-driven touchscreen, CNC programming, quick-change tooling, high-power spindles and immense rigidity, EX Series machines benefit from advanced technologies such as on-machine probing and dry milling techniques for certain materials. The added benefit of being able to accept extra-length components further underlines the flexibility of every EX-R-XL rotor milling machine. 

The PTG Holroyd EX-R-XL Series at a glance:

• Siemens SINUMERIK ONE CNC(FANUC CNC optional)
• Accelerated, simplified setup
• Programmable multi-cut process (for roughing and finishing)
• XL capability – extra travel and longer machine bed for components of extra-length
• Equipped for cutting with carbide and HSS tool systems 
• Choice of chucking and work-holding options
• Highly efficient, high-power milling spindle
• Hand-scraped beds for increased accuracy and reliability 
• Engineered for easy integration with automated parts handling systems
• Optional Renishaw LP2 Double Diaphragm Probe System 

PTG. The first name in precision
Incorporating the brands of PTG Holroyd and Holroyd Precision Rotors, PTG has established itself at the forefront of high-precision machine tool design, build and supply for specialised applications. The range includes advanced machine tools for the production of complex helical components such as compressor rotors, pump screws and high-accuracy gears. With production facilities in the UK, USA and China, Holroyd Precision Rotors manufactures the special purpose, ultra-precision helical components used in a wide range of industries, including refrigeration, air-conditioning, gas and vacuum pumping, industrial air handling, aerospace, medical equipment, motion control, power transmission, power generation, oil & gas, fluid transfer and high-end automotive. PTG also provides advanced technical consulting services.

www.holroyd.com