EOW March 2014

News Technology

Improvements in lubricants for super fine copper wire drawing

rely on the use of polymeric materials that exhibit “inverse solubility” properties.

The production of super fine copper wire has always placed great demands on lubricant manufacturers to develop products that satisfy the needs of this process. The high drawing speeds and small diameter (and hence low strength) of the wire mean that it is highly susceptible to breakages, resulting in reduced production efficiency. This can be as a result of inherent poor lubricity of the fluid or due to a build-up of deposits on the cones increasing

By Chris Nettleship, technical director, Metalube Ltd

Inverse solubility is a property exhibited by certain chemicals that runs counter to normal intuitive thinking. Everyone knows that higher temperatures means higher solubility. Whether it is laundry, washing dishes or in an industrial cleaning process, hot water or steam is better at cleaning because it is better at dissolving than cold water. For most chemicals this is indeed true. However for those that exhibit inverse solubility the opposite is the case. Higher temperature means that they become less soluble until the point they are totally insoluble in water.

performance, most current super fine wire lubricants are of the fully synthetic “chemical solution” type. They avoid the use of mineral or other oils which are insoluble in water and require the use of emulsifiers for them to mix with water as these have a tendency to form deposits that would be unacceptable in super fine wire machines. Instead all of the components of a chemical solution type product are fully water soluble meaning machines run cleaner. The challenge with chemical solution type products is to provide adequate lubrication. Water provides little or no lubricity in its own right so additives must be included that can provide this. Conventional chemical solution products

▲ ▲ Solution at 20°C, left, and Solution at 70°C

friction between them and the wire surface. A successful lubricant must therefore combine the properties of good lubrication with excellent cleanliness.

In order to deliver the required

▲ ▲ Samples at ambient 20°C

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March 2014