Advantages:

1. High structural rigidity and strength. It is integrally formed by forging or casting without segmented joint surfaces, delivering far superior bending and torsional resistance compared to assembled crankshafts, making it suitable for heavy-duty and high-speed internal combustion engines.

2. High operating precision and low vibration. Free of assembly clearances between segments, it features excellent coaxiality of main journals and crankpin journals with minimal rotational eccentricity, resulting in lower vibration and noise and easier compliance with dynamic balance standards.

3. Long fatigue life. The monolithic design eliminates stress concentration zones caused by segmented assembly, resisting fracture under long-term alternating loads and offering outstanding durability.

4. Simple assembly and compact overall engine layout. Disassembly and reassembly of the crankshaft are unnecessary, reducing the engine’s axial dimension and cutting assembly procedures.

Disadvantages:

1. High manufacturing difficulty and cost. Forming blanks for large forgings poses challenges and requires high-tonnage forging equipment. All journals, fillets and oil galleries must be machined in a single process, demanding complex tooling and driving up unit production costs.

2. Excessively high repair and replacement costs. Scratches, cracks or deformation on any journal render the entire crankshaft unusable, as damaged crank throws cannot be replaced individually. In contrast, assembled crankshafts only require replacement of faulty segments, leading to poor economic efficiency in maintenance.

3. Complex machining and heat treatment processes. Controlling distortion during integral quenching and nitriding is difficult; slender high-power crankshafts are prone to bending with tedious straightening procedures. Machining deep oil galleries is far more challenging than on segmented crankshafts.

4. Limited lightweighting potential. The one-piece structure allows little room for hollowing and weight-reduction design, resulting in greater self-weight than assembled crankshafts under equivalent power output.