Crankshaft is the core component of engine, its manufacturing process is complex, requiring high precision and high strength. The following is the main process flow of the crankshaft:

1. Material selection
Commonly used materials: forged steel, ductile iron, alloy steel, etc.
Material requirements: high strength, wear resistance, fatigue resistance.

2. Forging or casting
Forging process:
Heat billets to forging temperature (approx. 1200°C).
Use the forging press to form the crankshaft shape initially.
Advantages: dense tissue, high strength.
Casting process:
Suitable for nodular cast iron crankshaft.
Molded by mold pouring.
Advantages: Low cost, suitable for complex shapes.

3. Heat treatment
Normalizing or annealing: eliminate internal stress and improve processing performance.
Quenching and tempering: increase hardness and strength, enhance wear resistance.

4. Roughing
Turning: Machining the outer circle of the spindle journal and connecting rod journal.
Milling: machining both ends and keyways of the crankshaft.
Drilling: processing lubricating oil holes.

5. Finishing
Grinding: Precision grinding of the spindle journal and connecting rod journal to ensure that the size and surface roughness are up to standard.
Polishing: Further improve the surface finish and reduce friction.

6. Dynamic balance correction
Dynamic balance test: test the balance of the crankshaft when rotating.
Correction: Adjust unbalance by drilling holes or adding counterweights.

7. Surface treatment
Nitriding treatment: improve surface hardness and wear resistance.
Chrome plating or spray coating: enhanced corrosion resistance.

8. Cleaning and rust prevention
Cleaning: Removal of processing residues.
Anti-rust treatment: coating anti-rust oil or packaging protection.

9. Quality inspection
Dimensional detection: Use a coordinate measuring instrument to detect key dimensions.
Hardness test: Ensure that the hardness meets the requirements.
Non-destructive testing: such as ultrasonic or magnetic particle testing to detect internal defects.

10. Assembly
Assemble the crankshaft with other engine components (e.g. connecting rod, piston) for final testing.