WCA March 2011

This will lower the coefficient of friction and improve the adhesion of the coating to the metal surface. The fine crystal structure also increases the available surface area for the subsequent lubrication process. 4 A new type of lubricant as an alternative to soaps and MoS 2 The new lubricants are high performance polymer systems. Applied by immersion in an aqueous solution they produce thin organic coatings. results this lubricant is best used on top of a conversion coating. Application on bare material is possible but must be examined on a case-by-case basis and thus cannot be generalised. For maximum performance

Calcium phosphate coat prior to forming

Calcium phosphate coat after forming

Figure 4 ❍ ❍ : Cold heading wire prior to and after forming

The chart above shows the coating thickness as compared to the conventional lubricants used so far.

4.3 Benefits for the customer 4.3.1 Benefits of a polymer coating for the wire manufacturer or the pre-treater of rod sections. Using a polymer bath instead of a soap bath will provide the wire manufacturing plant with the following benefits: Polymer coatings need no soap powder in the drawing • die. This avoids the problem of dust formation affecting the operators. It reduces costs, as there is no need to purchase soap powder or to provide for its disposal. It also improves the reliability of the drawing machines because less soap dust settles on the machines and drives Improved forming means improved productivity • Clean wire is beneficial for subsequent processing • operations Improved corrosion protection helps the product store • for longer, providing customers with a better product 4.3.2 Benefits of a polymer coating for manufacturers of fasteners or cold extruders For wire processors, such as fastener manufacturers, this coating offers the following benefits: Improved extrusion accuracy due to cleaner material • Higher speed of the bolt heading machines • Longer tool life • Manufacture of parts with complex geometry that were • not possible before

4.1 Objectives of the new development The general target was to develop a coating that allows net shape forming without any negative impact on the tool life. This means that the forming accuracy should be appreciably better than that obtained when using soap, and should be at least equivalent to that obtained with MoS 2 . Moreover, the goal was to achieve a coating that is substantially cleaner and easier to remove. The lubricant concentrate should be classified in the lowest water hazard class and no additives were to be used that may present a potential corrosion risk. 4.2 Chemical principles of the new coating The newly developed polymer coating is a mix of high-molecular compounds that are free from heavy metals, boron compounds, mineral oil, chlorine or sulphur- containing lubricant additives (such as molybdenum disulfide and tungsten disulfide) or compounds based upon fluorine, for example, Teflon ® .

Figure 5 ❍ ❍ : Diagram of a continuous line treatment plant

Cold Extrusion

Continuous line treatment of cold heading wire or solid parts

Calibration draw of cold heading wire

Chemical

Calcium phosphate

Polymer

Cleaning

Cold Extrusion

Mechanical

90

Wire & Cable ASIA – September/October 2007 March/April 2011