“In cases where it is possible to identify a clear, high demand for very precise rotors, Holroyd looks at the opportunity and weighs the merits of investing locally in the equipment and systems to supply the market,” explains Holroyd Precision Rotors’ managing director Colin Carr. “The investment requirement is substantial, but there are many advantages – to our customers – in having satellite operations close to their manufacturing centres.
“In this instance, following the success of the rotor production cell we recently established in Chongqing, China, we decided to invest and develop a similar set-up in the US,” he continues. “In this case, we designed the plant to have sufficient production capacity and flexibility to meet a wide range of customer demands, while preserving the necessary agility to enable short changeover times and rapid batch switching. Additionally, we integrated a system of Kanban inventory controls to allow for ‘just in time’ delivery.”
Holroyd settled on premises in Spartanburg as it is a key centre for automotive manufacturing, has a rich engineering pedigree, a skilled labour pool, respected machine tool and cutting tool distributors, and good access to metals stockholders. Added to that, the state of South Carolina was keen to attract inward investment.
Holroyd Precision Rotors’ newly created facility covers 35,000 sq m, employs 30 staff locally and is supported by a team of specialist engineers from Holroyd’s headquarters in Rochdale, UK. A wide range of compressor rotors – with overall diameters up to 420 mm and lengths up to 1.5 m – is manufactured from a variety of materials at the facility, which is registered to ISO9001:2015.
After being milled and turned to size, rotor blanks are profile-milled then precision-ground using Holroyd’s UK-built machine tool technologies. Helical milling is completed using two Holroyd 3EX-R CNC rotor milling centres. Following profile milling and cylindrical grinding of shaft diameters, and depending on the components in question, rotor profiles are then finish ground on Holroyd’s TG and Zenith CNC helical grinding machines. Typical component tolerances are within ±10 micron on profile, lead and divide index.
“We seized the opportunity to build a rotor production cell to meet the requirements of our American customers,” concludes Carr. “We are now able to provide the manufacturing of our ultra-precise compressor rotors locally, which is a major benefit when it isn’t practical to ship large quantities from our UK site.”
