Kobe Steel certified for stronger crankshafts

The factor K is used in the calculation of the fatigue strength of steel components. Kobe was previously approved to a K-factor of 1.05, but the latest certification from ClassNK raises that to 1.15 – indicating a design margin of 15%.

Kobe said that the increased design margin is a result of proprietary refining techniques that minimise impurities in the steel, as well as a die-forging process that creates a stronger throw compared to the bending technique normally used.

The company noted that ship owners face increasing demands on engine room space from emissions abatement technology and bigger engines. “As a result, the need is growing for more compact engines to improve fuel efficiency and secure more cargo space,” it suggested.

The company claims that a crankshaft designed to bear higher loads could improve power output as much as adding an extra cylinder, contributing to the design of more compact, efficient engines.

Kobe Steel is planning to explore possibilities for weight and space savings with engine makers and ship builders.

The certification applies to cranks for built-up, rather than solid, crankshafts. This type of crankshaft is most often used in larger engines.