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Rotary Engineering simplifies high voltage coil radii forming for MRO service providers

10th February 2020
High voltage coil manufacturing requires specialist machines, which are the specialty of AEMT member, Rotary Engineering. The business has a strong track record in providing coil spreaders for the manufacture of high voltage coils, but has pushed the concept further by including a radius forming capability into its latest model. The result is simplified and expedited coil manufacture – adding flexibility to an inherently challenging process.

Ensuring the correct radius at both ends of a high voltage coil is paramount in delivering a uniform electromagnetic field. Traditionally, forming a coil into a radius would require hammering with a soft mallet, which demands extremely skilled workers to complete the task accurately. In most businesses, there will only be a handful of expert engineers entrusted with this lengthy task – which is hardly ideal when trying to provide a short lead time. Hammering coils into shape also takes its toll on the workforce too, with repetitive strain injuries a very real risk.Costly sophisticated CNC cold forming machines do offer an alternative with less hammering requirements. However, these are more suited to the needs of coil OEMs. Typically, an OEM will tailor designs to meet the limitations of its CNC machines, as pre-programming and machine capacity can only go so far. For repeatedly producing a small variance of coils to specific specifications, CNC machines make sense.


Optimised for the repair market


However, neither CNC machines or manual hammering are ideal for MRO requirements. Manual hammering simply takes too long, especially when juxtaposed against the need to reduce downtime for the customer. CNC machines also have limitations. While proficient at producing coils to a number of predetermined specifications, when it comes to producing exact replicas of coils that can vary wildly in specification for repair work, they are less so. For coil repair specialists, a more optimised solution is required.Simon Swallow, Managing Director at Rotary Engineering, explains their approach to the problem: “We are in a state of constant development when it comes to our machines. In this case, we wanted to see if we could find a way to incorporate radii forming of coils into one of our rotary coil spreaders. We wanted a machine that still reduced hammering to the bare minimum, but was also a more versatile and cost-effective option compared to a CNC machine.”

The end result is the Radius Forming Coil Spreader. A pneumatic machine that is loaded manually and controlled by a series of levers, the machine spreads the coil, lifts and twists it, before a final lever is activated to apply the required radius. All positions are formed to mechanical stops that are calibrated beforehand. The result is a coil that requires minimal hammering after it has been produced. While slower than a CNC machine, the entire forming process is complete in a matter of minutes.

Repeatability and flexibility

“The primary benefit of this machine is that it de-skills the coil forming process,” Simon explains. “While traditionally only a few select workers would be entrusted to apply the radii to a coil, the Radius Forming Coil Spreader allows the task to be completed accurately with high repeatability – minimising hammering post processing. This provides our customers with increased flexibility in terms of replicating coils, as repair work is not bottle-necked into a few experienced skilled workers. Strain on the workforce is reduced, and lead times are subsequently improved.

“It takes exceptional skill to form a coil manually with a hammer, backed by years of experience. Training employees to this level is very difficult, but the Radius Forming Coil Spreader bridges this gap, allowing more people to utilise the machine and gain a similar result. In the past, this simply hasn’t been an option. Combined with the extra versatility of coil replication compared to a CNC alternative, it’s a machine we feel is well suited to the MRO market.”

Rotary Engineering has a working prototype ready for demonstrations. With development complete, Rotary Engineering is now offering its customers the chance to specify the new Radius Forming Coil Spreader.

To learn more call +44 (0) 114 251 3134 or visit


Image 1: AEMT member Rotary Engineering has a strong track record in providing coil spreaders for the manufacture of high voltage coils.

Image 2: Rotary Engineering latest model includes a radius forming capability. The result is simplified and expedited coil manufacture – adding flexibility to an inherently challenging process.

About the AEMT

The Association of Electrical and Mechanical Trades (AEMT) was founded in 1945. It is an International Association representing leading companies in the electrical and mechanical service and repair industry. Members manufacture, distribute, install, service, maintain, and repair, electric motors, drives, pumps, fans, gearboxes, generators, transformers, switchgear, and ancillary equipment. In addition to motor and pump service facilities, most members operate mechanical engineering workshops for metal fabrication and the repair and refurbishment of worn components. Others include panel building facilities and some carry out repairs to industrial electronic equipment. Associate Members are companies that supply products and services to Members.Proceeding the publication of AEMT’s and BEAMA’s jointly produced first code of practice for The Repair and Overhaul of Electrical Equipment for use in Potentially Explosive Atmospheres, which was adopted as the initial IEC 60079-19 international standard. The association has put together a selection of Training modules covering the Theory and Practical nature to ATEX and IECEx equipment repair. The modules are delivered as accredited training courses by expert teams across the globe.

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