Page 26 - MetalForming June 2013

New Stamping Lubricants
tenacity throughout forming process- es. This enhances their performance in the press and helps prevent corro- sion on uncoated steel products.
Neat Oils and Oil-Based Emulsions for Coated Steels
Zinc-coated steels require a fresh approach to stamping lubrication. Zinc protects steel in two ways: it acts as a physical barrier to oxygen and moisture and as a sacrificial anode to the iron. For stamping these steels, neat oils provide the best anti-corrosion prop- erties because the oil residue is imper- vious to moisture, and oils create low conductivity.
The next-best alternative: oil-based emulsions, which can be made water- soluble with additives and emulsifiers. Emulsifiers are polar, with an affinity for water and oil. In effect, microscop- ic droplets of oil are dispersed and sta- bilized in water. As a residue on parts, water evaporates and leaves an oily film that protects against oxidation.
For use with multi-metal substrates, it is important that the lubricant not con- tain high levels of alkaline additives.
Synthetic lubricants form solutions in which the additives are dissolved in water. As a residue, most do not create a vapor phase to protect the substrate. Typically these products rely on amine salts for corrosion protection of ferrous alloys. The alkalinity of these salts cre- ates conductivity that can promote gal- vanic reaction, which accelerates the oxidation of the zinc to form zinc oxide, or white rust. If the residue is tenacious, such as with many synthetics designed for HSS, the oxidizing effect can be exacerbated from the presence of high- er film coatings. Where parts are in contact, the presence of water and alka- line salts creates a galvanic reaction in which severe corrosion can occur.
In galvanealled steel, iron is present in the zinc substrate. This alloy-like substrate makes this steel even more susceptible to galvanic reaction. Even- tually, zinc oxide can react with the
soap complexes in synthetics to form an insoluble zinc stearate that bonds with the substrate. In this condition, it is difficult to physically remove the corrosion with Scotch Brite pads. If removed, pitting or staining to the base metal remains.
Lubrication Application
Stampers can select from a number of lubrication options to avoid corro- sion concerns when stamping zinc- coated steel. Most European automo- tive OEMs ask their suppliers to use neat oils when stamping parts. Volk- swagen, for example, mandates that suppliers use oil (with one exception, a Fuchs emulsion called Montgomery DB 4265C); BMW requires the use of oil in all new-model stampings.
Neat-oil stamping lubricants still dominate the European and Asian mar- kets. The trend toward oil is driven by the need to eliminate corrosion, espe- cially on zinc-coated steel. Thixotrop- ic prelubes and hot melts are becoming
24 MetalForming/June 2013 www.metalformingmagazine.com
Quality Products, Inc., the parent company of Multipress, now welcomes
Pacific Press Technologies to the QPI family.
Headquartered in Mt. Carmel, IL, Pacific Press builds and services a broad line
of press brakes, shears and hydraulic presses. The company has an impressive 60-year record of product innovation and exceptional 24/7 field service.
QPI believes this acquistion will benefit customers with an expanded line of hydraulic metal forming equipment, and a new industry standard in customer service.
Quality Products, Inc.
NEWS!
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Columbus, Ohio