Lubricants in wire drawing: why lubrication matters

Lubrication may look like a simple step on paper: a film between wire and die. In practice, there's an entire science behind it, one that determines how long a die survives, how often a wire breaks, and how clean the final surface looks. So what exactly is this film, and what is it doing at the point of contact between wire and die?

What are wire drawing lubricants?

Lubricants are dry, greasy, or wet substances that are applied between the surfaces of two parts that touch each other, for example a metallic wire and the holes of drawing dies. During a wire drawing process, the drawing lubricants reduce friction and enable the wire to slide smoothly through the dies.

Wire is shaped by pulling it through drawing dies that reduce its diameter. Dies are made from tungsten carbide, natural diamond, or synthetic diamond, and the choice depends on the material being drawn. Inside the die, the wire passes through a conical opening that narrows progressively, squeezing the wire down toward its new, smaller diameter. It's exactly at this point of contact, where pressure and friction reach their peak, that the lubricant film has to do its job. In this process, lubrication is a simple but crucial step. A good lubricant film:

• reduces friction between wire and die
• prevents overheating
• reduces die wear and surface scratches
• extends die life
• cuts down on wire breaks
• improves overall wire quality
• increases the efficiency of the drawing machine

As drawing speeds and precision requirements rise, controlling friction, heat generation, and die wear becomes increasingly critical.

Dry drawing vs wet drawing: what types of lubricants are used in each application?

There are different types of lubricants used in the wire drawing industry, such as powders (soaps), emulsions, oils and oil-based lubricants, pastes, and fully synthetic lubricants. The proper lubricant application is crucial to efficient high-speed wire drawing. There are two main lubrication processes used in wire drawing: solid lubricants, which are used in dry drawing, and liquid lubricants, which are used in wet drawing.

Dry (solid lubricants): calcium and sodium-based soaps, phosphate coatings

Dry lubricants are powder-based materials, such as calcium or sodium soaps, used for low-carbon and high-carbon steel wire, e.g. spring steel wire, construction wire, cold-forming wire, and nail wire. In straight-line wire drawing machines, the wire passes through a lubrication box before entering the die, and the lubricant powder adheres automatically to the surface, forming a lubricating film. Dry drawing is used for heavy wire diameter reductions. The drawn wire carries a thin film of lubricant that helps with subsequent processing, such as the upset forging of headed components like screws, bolts, and rivets.

For drawing high-strength steels, a phosphate coating is often useful. The coating is highly adherent and can absorb the lubricant, acting as a lubricant carrier, and it prevents metal-to-metal contact even under high pressure. Before coating, the wire surface must be cleaned of rust and grease. The wire is then rinsed before being dipped in a bath containing phosphoric acid and zinc phosphate.

Liquid lubricants: emulsions, oils, pastes, and synthetic formulations

Wet drawing takes place in water tank wire drawing machines and is used for small-diameter wires with high surface requirements, such as wires made from non-ferrous metals like copper and aluminum, as well as low-carbon steel and stainless steel wires. Liquid lubricants take different physical forms: emulsions disperse oil in water, oils and oil-based products are used undiluted, pastes have a thicker, semi-solid consistency, and synthetic formulations use chemically produced base fluids instead of mineral oil. The wire is fully immersed in the lubricant during drawing, where the wet lubrication provides continuous cooling and lubrication, reducing friction and breakage throughout the process.

How are liquid lubricants made?

Wire drawing lubricants such as mineral, synthetic, and vegetable-based oils are manufactured through a series of complex processes. Manufacturing starts with raw ingredients such as crude oil, fatty acids, and alcohol, which are then blended, purified, and filtered. The main component is base oil, produced through the refining of crude oil. There are three main types:

• mineral base oils, derived directly from crude oil
• synthetic base oils, produced through chemical synthesis
• bio-based base oils, derived from renewable sources such as vegetable oils

The formulation and blending of lubricating oils involve the combination of base oils with additives to achieve the desired performance characteristics:

• detergents, used to clean and neutralize acidic compounds
• dispersants, which suspend and remove contaminants
• anti-wear agents, to reduce friction and wear
• antioxidants, to prevent oxidation and degradation

Where are wire drawing lubricants used?

Choosing the right type of lubricant for each application ensures better performance, less maintenance, and cost savings. Beyond standard products, lubricant manufacturers also develop tailor-made formulations for special wire drawing operations. Wire drawn with the help of these lubricants ends up in very different industries. The automotive sector, for instance, relies on ferrous wires for reinforcement, tire cord, wire ropes, springs, and fasteners, as well as non-ferrous wires such as magnet wires and conductors for electrical wiring. Construction is another major user of metal wire, from wire ropes for cranes and elevators to cables for building installations, alongside the growing fields of electricity generation and transmission.

Literature

Hofmann, H., Marcantoni, G.: Copper Wire-Drawing Lubricants.
Hofmann, H.: Aluminum Wire Drawing Lubricants.
In: Mang, Th. (ed.): Encyclopedia of Lubricants and Lubrication. Springer Verlag, Berlin, Heidelberg, 2014.
https://link.springer.com/referencework/10.1007/978-3-642-22647-2

Carlos del Rey, J., Guerrero-Vacas, G. (et.al.): Effect of Die Design and Lubricant on ZnAl15% Wire Drawing: An Experimental
Approach with Pressure/Hydrodynamic and Conventional Drawing Dies. Department of Mechanics, University of Córdoba, October 2025.
https://www.mdpi.com/2075-4442/13/11/481

Abd-Eltwab, A., Elmetwally, H. (et al): Experimental Study of Lubricant Effect on Wire Drawing Process.Beni-Suef University, Cairo, January 2020.
https://www.researchgate.net/publication/338621494_An_Experimental_Study_of_Lubricant_Effect_on_Wire_Drawing_Process

Prisco, U., Martinez, G. (et.al.): Effect of die pressure on the lubricating regimes achieved in wire drawing. In: Prod. Eng. Res. Devel. 14, 667–676 (2020). https://doi.org/10.1007/s11740-020-00985-6
https://link.springer.com/article/10.1007/s11740-020-00985-6#citeas

Narayan, A., Cardiff, Ph.: A Computational Fluid Dynamics Study of Lubrication Flow in The Wire Drawing Process. University College Dublin, April 2020.
https://www.researchgate.net/publication/341164285_A_Computational_Fluid_Dynamics_Study_of_Lubrication_Flow_in_The_Wire_Drawing_Process

Obi, A.I., Oyinlola, A.K.: Frictional characteristics of fatty-based oils in wire drawing. In: Wear, Volume 194, Issues 1–2, June 1996, Pages 30-37.
https://www.sciencedirect.com/science/article/abs/pii/0043164895066640?via%3Dihub

This technical guide was compiled by Dipl.-Ing. Konrad Dengler, an engineer and technical journalist specializing in materials science and industrial technologies.