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Providing precision boring for the power generation sector


Mirage Machines was approached to supply a portable, high accuracy boring machine for a power generation steam turbine project.

The client required a precision boring machine to complete accurate and repeated bores to a tight tolerance of ±0.005mm on diameter, parallel and perpendicular to a datum face. It was essential that any machine operated off precision jig plates for the repeatability.

Industry inefficiencies

Within the power industry, rotors are commonly exchanged within the steam turbine and generator. The joining coupling between the turbine stages and the generator are connected using fitted bolts.

The traditional practice is to align the couplings and then line bore the two couplings to ensure that all securing bores for the fitted bolts are in line. This operation is labour and time intensive within a planned shutdown.

Mirage's solution


To provide such a high accuracy boring machine Mirage designed its CBT range of boring machines to bore the turbine and shaft couplings ahead of the specified shutdown period.

By undertaking the application in advance, the pre-machined couplings could be removed and fitted with minimal effort, as well as ensuring completely accurate bore diameters and tolerances were achieved.

Subsequently, the boring process could be removed from the outage process using comparable/spare rotors for an outage exchange; saving valuable time, money and allowing the turbine and generator shafts to be simply exchanged.

The machines produced a repeated surface finish of 0.4 – 0.8Rα; which is exceptional for single point machining.

The whole process took three years to perfect; which demonstrates the commitment of Mirage and the customer to providing a workable solution to a time-consuming issue.

Other boring machines

Mirage Machines are proud manufacturers of high performance on-site machine tools. Since 1993 we have been producing portable machine tools that help to maintain operational excellence and maximise uptime of on-site assets.

We understand that on-site working conditions can be challenging so our range of portable boring machines are designed with ease of use in mind.

We pride ourselves on offering the most reliable, durable, efficient and precise portable machine tools on the market and our boring tools offer just that.

Mirage boring machines can be used for a wide range of applications including:

  • Excavator bucket reboring
  • Transfer gearbox housing reboring
  • Stern tubes
  • Drive shaft housing boring
  • A-frame supports

For more information on Mirage's boring machines, download our free buyers guide by clicking here.

Download our line boring machine buyers guide

Images © Mirage Machines

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