Conventional Francis Runner manufacturing used to be very tough as most of the metal removal between the buckets had to be done using manual grinders/polishers and it used to take months together for completion and in addition to this the operators had to be properly protected against grinding dust which is mostly responsible for the respiratory diseases. On top of this we had to compromise on the runner efficiency as the complete runner paths could never match with the actual designer’s 3D concepts. Material soundness would also be a very big issue as complicated construction would not allow access to Nondestructive tools. and finally, the CG of the runner would shift as metal removal will not be uniform which will lead to heavy residual balancing issues.

Well, that was the way we used to deal with single cast Francis Runners but now the story is different.

We have the buckets, the skirt and the crown castings separately machined, access to NDT tools is perfect. Runner efficiency is not compromised at all because all inlet and outlet water ways are machined to very fine accuracy and not ground anymore. Since all the parts are machined so CG does not shift much and hence no issues with dynamic balancing. Manufacturing is absolutely environment friendly and here you will find attached pics of many such Francis Runners getting ready for their final destinations in different parts of the world.