Surface burn on CNC crankshaft grinding machine is a common quality defect in crankshaft machining, manifested as yellow brown or blue black stripes on the surface of the workpiece, accompanied by abnormal surface hardness and crack risk, directly affecting the fatigue life of the crankshaft. The essence of this fault is that the instantaneous temperature in the grinding area exceeds the critical temperature of the material, causing a phase transition in the surface structure. A targeted process improvement plan needs to be developed based on the cause.

The core causes of burn faults can be attributed to "excessive heat input" and "insufficient heat output". Unreasonable grinding parameters are the main cause, such as high grinding wheel linear velocity, fast feed rate, or excessive back cutting amount, which can lead to excessive energy accumulation in the grinding area per unit time; Cooling system failure is secondary, including insufficient coolant supply, nozzle angle deviation leading to cooling blind spots, or coolant deterioration reducing heat dissipation efficiency; Improper selection and maintenance of grinding wheels can also exacerbate problems, such as decreased cutting ability after blunting of grinding wheel grains, and additional heat generated by repeated friction.

Optimization of grinding parameters is the key to controlling thermal input. It is necessary to follow the principle of "low-energy cutting", appropriately reduce the linear speed of the grinding wheel, and reduce heat generation by reducing the impact friction between the abrasive particles and the workpiece; Reasonably increase the feed rate and reduce the back cutting amount to avoid energy concentration in a single grinding process while ensuring machining efficiency. For complex parts such as crankshaft bends, a segmented grinding strategy can be adopted to adjust parameters separately for burn prone areas, balancing accuracy and heat dissipation requirements.

Cooling system improvement focuses on improving heat output efficiency. Adopting a high-pressure and high flow cooling pump, coupled with an adjustable angle universal nozzle, to ensure precise spraying of coolant to the grinding area, covering the contact point between the grinding wheel and the workpiece; Regularly replace the coolant and clean the filtration system to prevent impurities from clogging the nozzle or reducing heat dissipation performance; Under high-temperature grinding conditions, oil-based coolant can be used instead of water-based coolant to reduce frictional heat generation due to its better lubricity.

The scientific selection and maintenance of grinding wheels cannot be ignored. Prioritize using grinding wheels with moderate hardness and loose structure to reserve space for debris storage and coolant penetration; According to the characteristics of the crankshaft material, choose corundum or silicon carbide abrasive grinding wheels to ensure cutting sharpness; Establish a regular grinding wheel dressing system, restore the cutting edge of abrasive grains through diamond pen dressing, and avoid friction burns caused by blunting the grinding wheel.