Lubricants In Wire Drawing: Types and Advantages
Lubrication In Wire Drawing and Its Importance
As the metal is drawn through the dies, friction can generate significant heat and wear down the dies. Lubrication plays a vital role in the wire drawing process, as it reduces friction between the wire and the die, extending the life of the die and improving the quality of the finished product. Lubricants such as talc or oil-based lubricants are applied to the wire and die to reduce friction and enable the wire to slide through smoothly. Proper lubricant application and type is crucial to high-speed, efficient wire drawing.
Different soaps and oils also serve as lubricants. Polymers or soft materials are also used as lubricants for hard to draw metals. Usually, passing the rod through dry soap can provide adequate lubrication as it moves towards the die. Some designs may require synthetic lubricants that are pressurized into the dies. This ensures continuous lubrication throughout the metal drawing process.
Types Of Lubricants In Wire Drawing: Dry Drawing And Wet Drawing
Wire drawing employs both solid and liquid lubricants. When solid lubricants are used, the process is known as dry drawing, while liquid lubricants is referred to as wet drawing.
Wet Drawing
Wet drawing is a wire drawing technique that involves completely submerging the work in lubricants. For this method, the lubricant is typically an oil containing various chemical additives. Usually, a mixture of soap solution with up to 3% oil is used in wet drawing. When drawing copper, silver, gold, and platinum wires, soap emulsions with water and fatty oils are commonly used as lubricants. Petro-oils with fatty oils are used for aluminium wires. Wet drawing is well-suited for fine wires since wet lubricant is easier to remove.
Dry Drawing
In the dry drawing process, lubrication is applied to the material in the form of a solid powder. Solid lubricants are typically a mixture of soap powder, graphite, and lime. A stuffing box is used to apply the lubricant, which is positioned in front of the die. As the work passes through the box, it picks up lubrication before entering the die. The wire can become quite hot during the drawing process, causing the soap to melt. However, the lime helps to maintain the lubricant's viscosity, ensuring that a lubricant film is maintained on the interface and preventing metal-to-metal contact between the die and wire.
Factors Affecting Wire Drawing Lubricant Selection
- Metal composition: Different metals require different lubricants for efficient and high-quality wire drawing.
- Surface condition of both the rod and wire: Smooth initial wire rod require different lubricants than rough or dirty surfaces. Intermediate wire condition also affects lubricant needs.
- Machine design, constraints and auxiliary equipment
- Design of the wire drawing dies
- Drawing speed
- Drafting approach: Harsher drafting requires more lubrication than gentler methods.
- Downstream application requirements: The intended use of the wire after drawing can impact lubricant selection.
🔗Application and advantages of wire drawing
Advantages Of Wire Drawing Lubricants
Reduced Friction: Lubricants minimize friction between the wire and die, allowing the wire to slide through more easily at a lower force. This enables fine control of the drawing process.
Prevents damage and Improved product quality: Lubricants protect the wire surface from scratches, scoring, galling or rupture that could weaken the material or produce an undesirable surface finish.
Lower operating temperatures: Lubricants can help to dissipate heat generated during the drawing process, reducing the operating temperature of the drawing dies and preventing overheating and equipment damage.
Enables wider material range: Many materials that are difficult to draw without lubrication can be drawn with an appropriate lubricant. This allows the production of wire from more metals, alloys, polymers and composites.
Enables deeper reductions: By reducing friction and allowing the wire to be drawn at lower forces, lubricants permit a larger reduction in diameter with each pass. This results in fine gauge wire that would otherwise be impossible to produce.
Prolongs die and machine life: Lower friction helps dies and other components last longer before needing replacement. Hence minimizing the downtime.
Increased drawing speed and higher productivity: Lubricants can allow higher drawing speeds by reducing the friction between the wire and the drawing dies.
Cost savings: The use of lubricants can lead to cost savings by reducing equipment wear and tear and minimizing downtime for maintenance and repairs.
