**2. Measurement of bearings and journals**

In the following sub sections, the methodology of measurements and use of instruments are shown. The bearings (**Figure A1**) and journals are manufactured as per design outputs and are measured for dimensional precision.

#### **2.1 Measurement of bearing sizes**

 Three parameters: (1) internal diameter, (2) surface roughness and (3) roundness of internal surface were measured critically. As **Figure A2** shows, the internal diameter was measured taking six observations each at 30° intervals circumferentially and axially at three planes (two end planes and one central plane) giving a total of 18 readings for each bearing. The internal diameters at the end planes were measured using an optical tool makers microscope with an accuracy of 1.0 μm. While the central plane internal diameter, being not possible to measure with an optical tool makers microscope, an optical comparator with a 1.0 μm accuracy was used. The sample readings are shown in **Table 1** for bearing 3. **Table 2** shows the summary of all the three bearing diameters measured.


#### **Table 1.**

*Sample observations for internal diameter for bearing 3.* 

*Metrological Measurements of Water Lubricated Hydrodynamic Bearings DOI: http://dx.doi.org/10.5772/intechopen.81083* 


**Table 2.** 

*Summary of bearing diameters measurements.* 

#### **2.2 Measurement of surface roughness and roundness**

For the measurement of the surface roughness (as shown in **Figures A3** and **A5**) at different locations, *TALYSURF* with an accuracy up to 0.1 μm was used at two locations axially and three locations circumferentially. The axial travel was 6.4 mm of the stylus and vertical magnification for the plot (graph) was selected as 1000 and horizontal magnification as 50. The maximum surface roughness found for bearing 1, 2 and 3 were 0.89, 1.58, and 1.63 μm respectively.

For checking the roundness, *TALYROND*, with an accuracy up to 0.1 μm was used. **Figure A3** shows the locations for checking roundness of internal diameter surface. The ovality measured for bearings 1, 2 and 3 are 5, 10 and 5 μm respectively (**Table 2**).

#### **2.3 Measurement of journal sizes**

 The measurement procedure for measuring the outer diameter is slightly different from the earlier one followed for bearings, though, the locations where measurements are made as shown in **Figure A5** are similar for the bearing. For the measurement of the outer diameter, a dial comparator with an accuracy up to 1.0 μm was used. Similar to the bearing locations, the observations were taken in axial directions at three different planes (two end planes and one central i.e. mid plane). Circumferentially, six readings each at 30° intervals were taken. This means, there were 18 readings for the diameter for each journal (**Figure A4**).

The surface roughness and ovality measurements (**Figure A6**) were carried out using a similar procedure and instruments as in the case of bearings discussed earlier. **Table 3** summarizes the extracted results from the measurement of journals. **Table 4** compares the specified (by design) clearances versus actual obtained clearances.


#### **Table 3.**

*Results from measurement of journal.* 


#### **Table 4.**

*Clearances from measurements.* 

## **3. Conclusions from measurement**

From the measurements of the bearings and journals, the following conclusions are drawn.

