May 2026 Volume 8

AUTOMATION effect is undesirable in forging because it generates unstable cooling behavior and can cause temperature “hot spots” despite high media consumption. Well‑designed external atomization enables high operating pressure without entering detrimental Leidenfrost regimes on the macroscopic scale. Key mechanisms include the following: Fine droplets that evaporate rapidly before forming large vapor cushions. Controlled momentum ensures droplets penetrate the initial vapor layer and wet the surface momentarily. Short spray pulses with adequate dwell time between passes, allowing vapor to dissipate. It is important to note, high operating pressure, but not too high, results in the best cooling with highest heat reduction. External‑mixing nozzles provide this tunable operating window more reliably than internal‑mixing designs. Die Temperature Cooling Considerations Typically, at the start of lubricant spray, die temperature is high, approaching the Leidenfrost regime. As the spray is applied under optimized conditions, the surface temperature decreases from the Leidenfrost region to the wetting temperature, where stable film boiling gives way to nucleate boiling and effective wetting. Then we enter the high evaporation regime, where evaporative cooling is most efficient. As temperature falls further toward the boiling temperature of water, evaporation rate decreases and approaches zero evaporation, where further spraying provides diminishing returns. Figure 5. highlights these temperature regions.

External atomization, by maximizing the fraction of water that evaporates on the die surface, allows for higher cooling capacity per unit volume of water, reduced water usage for the same heat removal and lower energy input for media handling (pumping, treatment, disposal). For forging operations, this translates into a combination of improved thermal management and environmental benefits. Conclusion In summary, a deep dive into the characteristics and methodology of lubricant spray highlights the following result. External atomization of cooling and lubricant spray provides a robust method for optimizing die temperature and lubrication in closed‑die forging operations. By generating fine droplets with adjustable size and momentum, external‑mixing nozzle systems achieve superior surface coverage, maximize evaporative cooling, and minimize waste. The infographics presented demonstrate and highlight the inefficiencies of poor atomization, the influence of nozzle design and operating pressure on droplet size, and the thermodynamic advantages of evaporation. It further establishes, via comparative performance metrics, that systems based on external atomization outperform conventional internal‑mixing nozzles with respect to cooling capacity, cycle time, media consumption, die life, and overall cost. For forging plants seeking to increase productivity, enhance part quality, and reduce environmental impact, investment in externally atomized spray systems presents a technically and economically justified solution. Future work can integrate real‑time monitoring of die temperature and spray deposition with adaptive control of external atomization parameters, further leveraging the inherent flexibility of these systems. Mackay Wilson P.Eng. Area Sales Manager

AED Automation Inc. Phone 226-374-5427 Email: mackay.wilson@aed-automation.com

Figure 5: Die Temperature vs. Effective Lubricant Spray

The chart concludes that the best cooling effect can be achieved by evaporating water. In other words, the goal is not to flood the die with liquid but to operate in a regime where most of the spray evaporates on impact at elevated temperature. External atomization contributes in two crucial ways: 1. Rapid transition through Leidenfrost: Fine droplets and controlled momentum enable quick penetration of the vapor barrier, moving the surface into the effective evaporation temperature range. 2. Tight temperature window: Because cooling is efficient and controllable, the die temperature can be maintained within a narrow band between blows, improving consistency and reducing thermal fatigue.

FIA MAGAZINE | MAY 2026 36