May 2025 Volume 7

EQUIPMENT & TECHNOLOGY

lubrication and plant cleanliness are essential. These lubricants offer partial “Elastohydrodynamic” lubrication (middle section of the Stribeck Curve” and also part the tooling and workpiece surfaces Engineering Lubricant Performance: The Multivariable Equation Lubricant selection is a multivariate optimization problem that involves: • Forming and Die Temperatures: High-temperature processes (>2000°F) require different lubrication strategies than warm forming (<2000°F). Die temperature also governs wetting behavior—water based systems lose effectiveness above 550°F unless chemically enhanced. • Metal Flow Severity: Complex operations such as extrusion, severe lateral flow, or deep drawing demand lubricants with superior adhesion and flow-extension properties. • Press Characteristics and Production Volume: Whether mechanical, hydraulic, or hammer, the type of press affects forging conditions and lube film behavior. High-volume applications with tight cycle times demand robust and consistent lubricant performance. • Application Method: Spray, dip, swab, and flood methods all require different viscosities, atomization characteristics, and thermal properties from the lubricant. Matching these parameters with the correct, optimized lubricant formulation directly impacts consistency, tooling longevity, and throughput. Advancements in Film Engineering and Tribological Control Soft-film graphite lubricants are among the most significant recent breakthroughs. These films, in the right processes, maintain the protective qualities of traditional hard films but with improved sprayability, adhesion, and cleanability. However, there are specific applications

which require thicker, hard films for optimized performance and enhanced metalflow. Soft films also eliminate common issues such as electrical interference from graphite overspray, reduce machine downtime, and enable more precise lubricant targeting. In emulsion systems, wetting at elevated temperatures has historically been a barrier due to the Leidenfrost effect. Advanced formulations now include additives that break the steam barrier, enabling consistent wetting above 550°F. This development is critical in isothermal forging of non-ferrous alloys, where uniform lubrication is essential. Additionally, newly engineered EP (extreme pressure) additives and friction modifiers have improved boundary lubrication properties, lowered required tonnage, and expanded

mechanical, and geometric demands. Advances in formulation, film science, and application methodologies have made it possible to improve metal flow, reduce friction, extend tool life, and ensure consistent part quality across a wide range of forging environments. As the forging industry continues to pursue higher performance and operational efficiency, the integration of modern tribological science into lubricant design and use will remain essential. Further discussion of these topics and more will occur at Forge Fair in Cleveland, OH on Wednesday May 14th at 10:50am. AML will present Forging Lubricants: Advancements in Tribology and Applications for Optimal Performance. Please join us for an informative discussion of these topics in further detail.

metal flow without increasing material resistance. These improvements reduce stress and extend tool life in demanding conditions. Application and Handling: The Often-Overlooked Variable Even the most advanced lubricant formulations will fail if not properly applied. Atomized spray

Figure 1: Stribeck Curve

application remains the most effective method for water-based lubricants at die temperatures up to 550°F. Key factors for application include spray pattern, sprayed droplet size, spray pressure, spray angle, and others. On the handling side, proper agitation is critical—particularly for graphite-containing systems. Factors such as blade choice, blade positioning, mixer RPM’s, and numerous other variables are key to lubricant handling success. Conclusion Forging lubricants are no longer one-size fits-all solutions but highly engineered components that must be precisely matched to each operation's thermal,

Frank Sobnosky Jr. Chemical Engineer AML Industries, Inc Phone: 330-399-5000 Email: fsobnosky@amlube.com www.amlube.com

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