Tribomechanical Forming Processes
We quantify your thermo-mechanical loads and tune shear viscosities, release activities, and melt phases to your process kinetics.
Hot Extrusion
During hot extrusion of copper, brass, and aluminum alloys, a preheated billet is forced through a die. Contact temperatures in the die gap reach 700°C to 1000°C under high hydrostatic pressures. The process requires highly effective separation at the die surface and the mandrel bar.
Extreme contact temperatures and high deformation speeds lead to cold welding (material transfer / pick-up) on the extrusion tooling if lubrication is insufficient. This drastically increases tool wear. At the same time, the lubricant carrier media must sublimate cleanly and without ash or soot to prevent carbon deposits on the inner tube surfaces, as these block subsequent capillary solderability. Friction must be controlled to ensure a homogeneous material flow and to prevent cracking at the end of the profile (back-end defects). Dies made of hot-work steel must also be protected from thermal shock.
Challenges
Die edge erosion due to extreme flow velocities, scale-induced wear, stick-slip behavior, and thermo-mechanical tool shock in continuous operation.
Lubricant Requirement
Thermochemical adhesion on hot-work steel at T > 800°C, shear stability under boundary lubrication conditions, and complete thermal decomposition (TGA) without carbon residues.
Recommended Process Solution
The PROMET LUPRIT Extru-Lube / Syn-Wax series for copper tube extrusion combines ash-free carrier waxes with inorganic barrier substances to form a resilient molecular protective film under extreme contact pressures.
Economic OEE Benefits
- Increase in mandrel and die service life by up to 30% through reduced abrasive wear
- Minimization of cracking and surface defects at the back end of the profile
- Residue-free, ash-free sublimation ensures solderability according to DIN EN 1057
- Homogeneous force curve in the container increases extrusion speed by up to 15%
Warm Extrusion
Warm extrusion combines the dimensional accuracy of cold forming with the reduced flow stress of hot forming. It usually takes place at temperatures from 350°C to 650°C.
Due to the reduced billet temperature, metal flow stress is higher than in hot extrusion, resulting in extreme contact pressures in the die gap. The shear viscosity of the lubricant must remain stable across the entire thermal process window to prevent tool galling. Local temperature gradients in the tooling also lead to unstable metal flow, geometrical deviations, and surface defects. Therefore, high-performance Extreme Pressure (EP) lubricants are required, which must be easily degreased after forming.
Challenges
Local temperature gradients in the tooling, adhesive material transfer (galling) at high deformation rates, ensuring a stable metal flow.
Lubricant Requirement
Pronounced Extreme Pressure characteristic for wear reduction, protection of the die against thermal fatigue, complete aqueous-alkaline degreasability before subsequent steps.
Recommended Process Solution
PROMET LUPRIT FormFlow / Draw-Lube formulations feature high adhesion on heated billet surfaces, homogenize friction coefficients, and reduce required forming forces in the mixed lubrication regime.
Economic OEE Benefits
- Prevention of cold welding and seized workpieces during forming
- Up to 25% extension of die lifecycles in the high-stress mixed friction zone
- Minimization of cracking at critical geometrical edges and corners
- Excellent, residue-free degreasability in standard aqueous-alkaline cleaning baths
Hot & Cold Pressing
In forging and pressing processes, minimizing friction is crucial for optimal die filling. Process efficiency is directly determined by release behavior and the avoidance of metal pick-up.
Releasing the workpiece from the die cavities represents the main challenge. If the part sticks in the tooling, costly process interruptions and tool damage occur. In highly stressed radii of the die, extreme stress peaks occur, leading to fatigue cracks if release performance is insufficient. The lubricant must be physiologically safe and must not leave sticky or varnish-like residues on tool surfaces.
Challenges
Insufficient release (sticking in the die cavity), development of thermo-mechanical fatigue cracks in highly loaded tooling radii without proper lubrication.
Lubricant Requirement
Formation of stable release films at high cycle rates for cooling and lubrication, physiological safety of carrier media, clean tool surfaces.
Recommended Process Solution
PROMET LUPRIT PressRelease emulsions are based on water-dispersed, chlorine- and heavy-metal-free additive systems for reliable release and cooling of highly loaded dies and punches.
Economic OEE Benefits
- Reliable ejection behavior and complete elimination of sticking delays
- Reduction of thermo-mechanical cracking in the die cavity
- Higher cycle rates and optimized throughput for complex part geometries
- Clean tooling surfaces without sticky or hard varnish additive build-ups
Drawing & Sizing Processes
Cold drawing and sizing of precision and copper tubes on bull blocks or linear draw benches operates in the mixed hydrodynamic lubrication regime. Continuous friction minimization is required to secure tight tolerances and low roughness.
Extreme shear rates in the narrow gap between drawing die and tube cause high thermal loads. Unstable sliding friction coefficients lead to chatter marks (stick-slip effect) and tube breaks. Drawing dies made of tungsten carbide or PCD are subject to severe abrasive wear. Drawing lubricant residues must evaporate completely during subsequent annealing.
Challenges
Boundary layer overheating, unstable sliding friction coefficients, wear of drawing dies (TC/PCD), and carbon residues during heat treatment.
Lubricant Requirement
Viscosity shear stability at high drawing velocities, ash-free vaporization under inert/reducing annealing atmospheres to prevent staining.
Recommended Process Solution
The PROMET LUPRIT Draw-Lube / Syn-Wax product line is based on high-purity synthetic esters and ash-free EP additives, combining optimal load-carrying capacity with residue-free pyrolysis.
Economic OEE Benefits
- Enabling drawing speeds over 20 m/s with highly stable sliding friction
- Minimized abrasive wear on diamond and tungsten carbide drawing dies
- Significant reduction in tube break rates in the sizing area
- Optimal surface quality (Ra < 0.2 µm) and bright finish after annealing
High-Temperature Applications
Thermal limit ranges at T > 1000°C (such as extrusion of titanium or nickel-based alloys, and furnace transport systems) require inorganic phase transition layers. Conventional organic hydrocarbon compounds decompose instantly in these temperature ranges, leading to immediate boundary lubrication failure.
This causes severe tooling wear, cold welding, and high friction values, which can stall the extrusion process. At the same time, the heated metal must be protected from oxidation and scaling. The release medium must additionally act as a physical oxygen barrier to minimize scaling losses and surface decarburization.
Challenges
Oxidation and thermal breakdown of organic additives, increased scale formation in the die channel, abrasive die erosion under high pressures.
Lubricant Requirement
Oxygen barrier function to prevent scaling, preservation of sliding activity at T > 1000°C, physiologically safe solid carriers with thermochemically inert structure.
Recommended Process Solution
PROMET LUPRIT BN-Shield boron nitride dispersions and PROMET LUPRIT Graph-Lube graphite systems form a thermochemically inert, pressure-stable barrier at extreme temperatures. Our PROMET Stick-Lube solid lubricant sticks are used for automated mandrel and die application.
Economic OEE Benefits
- Maximum protection against high-temperature corrosion, oxidation, and scale on profiles
- Prevention of tooling welding and pick-up under extreme contact temperatures
- Extension of maintenance intervals for furnace components and transport systems
- Process reliability for critical parts through robust inorganic barrier layers
3 Steps to Tribological Approval
We analyze the tribomechanical load spectra of your extrusion and drawing plants for the targeted design of high-temperature-resistant release and sliding media.
Tribometric Parameter Intake
Recording of tool geometries, forming speeds, shear rates, and peak thermo-mechanical loads.
Practical Formulation
Optimizing melting profile, viscosity, and thermal behavior for residue-free evaporation under operating conditions.
On-Site Validation
Metrologically supported trial run to record surface quality and die lifespan limits.