Manufacturers of high capacity diesel engines are maintaining close tolerances in terms of taper and ovality of crankpin and main journal diameter of the crankshaft. The maintenance of close tolerances and high surface finish results in the generation of more power, longer life of crankshaft and bearing, less noise level, low vibration, friction, and better fuel efficiency. RA Power Solutions has been working on crankshafts of marine engines and engines used for various applications with diameters ranging from 30 mm to 700 mm.
In general, the following close tolerance of the crankpin and main journal are observed:
I) The Taper and ovality of the crankpin and the main journal are maintained between 0.02 mm to 0.05 mm depending on the diameter of the crankpin and main journal.
II) The surface finish of less than 0.25 RA value is maintained.
RA Power Solutions has observed that sometimes due to an emergency, to put back the engine into operation, the crankshaft crankpin and main journal are hand polished with emery paper, nylon rope, and other means. This has serious consequences for the CR pin and the main journal. A few of them are as follows:
I) Bearing line marks, and pitting marks are observed on the crankpin and the main journal of the crankshaft cannot be removed by hand polishing.
II) It is our experience that in the case of the development of taper and ovality, it can never be reduced and controlled by hand polishing. On the contrary ovality and taper increase.
III) The surface finish of the crankpin and main journal is of great importance.
IV) It is observed that by hand polishing the marks can never be removed fully. Thus the desired surface finish as per the manual cannot be maintained.
RA Power Solutions, during their work on high-capacity engines installed with clients, spread all over the world, have observed that in most cases hand polishing rather deteriorates the condition of the crankpin and main journal and in some cases results in the rejection of the crankshaft.
Recently one of our clients has 3 generators of MAN B&W 8L 23/30 had a problem in all crankpins having a standard diameter of 185mm. Bearing line marks and a rough surface were observed. All the crankpins were hand-polished by nylon wire and new bearings were used. The crankshaft failed within 20 minutes of the operation of the engines. A few photographs are given below:
Introduction of Portable Crankshaft Grinding Machine by RA Power Solutions
RA Power Solutions have introduced a portable, lightweight onsite crankshaft grinding and polishing machine which is capable of grinding and polishing diameters ranging from 30 mm to 700mm. The onsite crankshaft grinding machine is revolutionary portable equipment that can be inserted from the inspection window of the engine block. There is no requirement for the removal of the crankshaft from the engine block.
RA Power Solutions specializes in crankshaft polishing, offering high-quality services to improve the performance and longevity of crankshafts. our skilled technicians utilize state-of-the-art equipment and cutting-edge techniques for precise and efficient crankshaft polishing. The use of a dedicated crankshaft polisher ensures that the polishing process is done with utmost precision and consistency.
On site crankshaft grinding and polishing machine is easy to operate and we also extend training to the buyer’s technicians. Inviting companies to polish of crankshaft is no longer required as it can be undertaken by your technicians with the portable onsite crankshaft grinding machine. You can save on the exorbitant amounts charged by European companies, which was their monopoly till the last few years.
More than 70 machines have been sold all over the world and are operating successfully.
The author is Mr. Raj Shahani, Managing Director of RA Power Solutions Pvt. Ltd. He has 40 years of experience working on large crankshafts and Diesel Engines. He is on the board of directors of reputed shipping companies and companies having a large number of Diesel power plants.
The crankshaft grinding and crankshaft polishing machine has been developed through consistent and focused R&D with field trials undertaken in different conditions.
For more information on crankshaft polishers, please email us at rajshahani@rapowersolutions.com, or info@rapowersolutions.com, or call us at +91 9582647131 or +91 9810012383.
