Greenray Turbine Solutions Ltd – Rotor Shaft Electrical Runout Correction

Greenray Turbine Solutions Ltd – Rotor Shaft electrical runout correction
4th December 2019 – 10th April 2020

What scientific or technical knowledge or capability existed at the start of your project that you planned to improve?

Part of the manufacturing process to produce a Rotor Shaft is to carry out electrical runout checks (Glytch checking) on the probe track areas.  There is a tolerance allowable that the values should fall within to be acceptable and compliant to drawing.  The tolerance is defined as a value in tenths of thousands of an inch.  The electrical signal in Mv (Milli-volts) is then converted into microns.

Should the readings taken be out of tolerance then remedial work has to be carried out to bring the readings within tolerance.  The recognised method for this remedial work is to diamond burnish the probe tracks and then re-take the readings.

In this case the probe tracks were out of tolerance and were therefore diamond burnished and new readings taken.  These were still out of tolerance but had made some improvement.

The diamond burnishing process was repeated twice more but there was no further improvement made to the readings.

Other means of improving the probe track values had to be developed.

What is the advance in knowledge or capability?

A process was developed in order to change the surface texture of the areas which were out of tolerance.  We had to consider how to get high values down and low values up.

This meant that some areas had to be polished to a better surface finish and others had to be changed to a coarser surface finish.

Since we were applying these techniques to individual small areas the process had to be carried out by hand and therefore this became a very labour intensive exercise.

After considerable trials using various mediums we successfully brought each probe track within tolerance.

What scientific or technological uncertainties did you face?

The initial problem was deciding whether a high value should be polished to a better surface finish or should it be made a rougher surface finish.  The same problem applied to how we improve a low value.

Also to what extent did we need to adjust these finishes to get readings within tolerance and therefore what mediums do we use to achieve the desired results.

How did your project overcome these uncertainties?

The reality in solving these problems could only be by trial and error.

Fairly quickly we were able to establish which surface finish affected the high and low values.

To what extent was somewhat more difficult and therefore we carried out trials using many different polishes and abrasives until we could establish which had the best and desired effects.

If you like advice on your project then get in touch with PT Engineers today or take a look at our capabilities on our website.