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Chlorinated paraffins (CPs) are still the most popular and widely used extreme pressure lubricant additives in metalworking fluid formulations. They offer numerous ad vantages: Versatility for use in both oil- and water-based formulations; ease of formulation; activity in a wide range of temperatures and conditions; lightness of color; and cost efficiency. Although short-chain CPs (C18) are available, and Dover Chemical, the only CP manufacturer in North America, is committed to maintaining a secure supply to the market.

However, there is some uncertainty regarding future regulations (to keep up with the latest regulatory developments, visit the Chlorinated Paraffins Industry Association website at www.regnet.com/cpia). In response to this and to market trends of increased emphasis on green products and greater value of public perception of a green image, many lubricant manufacturers and blenders are investigating alternative approaches.

Dover helps formulators meet market needs for a greener image with a wide array of CP alternatives that are readily biodegradable, offer ease of disposal, and are free of stringent regulations. They also contain no chloride, thus avoiding corrosion issues posed by CPs in applications for mild steels. Several are chlorine-free.

These alternative chemistries include chlorinated fatty esters and acid, sulfurized hydrocarbons, phosphate acid esters, a phosphorus-containing blend, boundary ester lubricants, complex esters, hydrogen phosphites, and a nitrogen-containing compound. Their use requires formulating skill, as they are more application-specific and more selective to the base carrier. Some phosphate esters are less stable in water. Most alternatives are limited to non-stainless applications; however, one patented additive was developed specifically for stainless and other hard-to-machine alloys.

Laboratory Testing Data Water-based, Soluble Oil, and Semi-synthetic Formulations

In this water-based formulation, the chlorine-free phosphate amide Mayfree 133 provided extreme pressure performance equivalent to that of long-chain chlorinated paraffin.


While many of the chemistries provide equivalent tap efficiency to that of long-chain chlorinated paraffin, performance of the chlorinated methyl ester, DA-8506XS, was superior.


Inversol 140, an inversely soluble complex ester, provides superior performance to long-chain chlorinated paraffin. Water-soluble at temperatures <140 degrees C, it becomes more oil-soluble at higher temperatures, which helps deliver more protection to the interface of tool and metal.


Many of Dover’s chemistries are equivalent or better alternatives to long-chain chlorinated paraffin in soluble-oil formulations for draw-bead applications. In this test, the chlorine-free phosphate amide Mayfree 133 provided superior performance.

Performance comparisons testing
Dover Chemical conducted testing to compare performance of appropriate additive chemistries to that of chlorinated paraffin in typical lubricant formulations used in common metalworking applications. The additive used as the standard for comparison is Dover’s Paroil® 140, a long-chain CP (40% Cl). The following tests include one product from each applicable chemistry group. The additives included in these tests are for simplified comparisons for key applications, rather than recommendations. Dover works with customers to choose additives for testing to determine the best chemistry for their specific lubricant formulation and formulating needs.

Methodology
Tests were conducted on steel and stain less steel. Metal removal was measured by tapping using Microtap; metal forming was measured by drawing using Draw-Bead and Falex EP. Formulae included neat oil, soluble oil, and semi-synthetic as follows:

• Neat oil – 5% additive in 100 sec oil;
• Soluble oil – oil + emulsifier base + additive, 5% emulsion in tap water, 0.0375% final additive concentration;
• Semi-synthetic – 60/40 oil-water base, 0.15% final additive concentration.

Dover’s patented Doverlube NCEP was developed for use in stainless steel and other difficult-to-machine alloys. In stainless, Doverlube NCEP yields 109% tapping efficiency compared to the long-chain CP Paroil 140. Effective synergies can again be achieved with a Doverlube NCEP/sulfurized blend; this synergy also holds true in drawing. NCEP is an extremely versatile alternative to chlorinated paraffin. In addition to 300 Series stainless steels and A 286, it can be used for all exotic alloys such as Inconel, titanium, Hastelloy and waspaloy. The additive’s chlorine-free chemistry avoids stress corrosion in stainless steel and titanium. In addition to hard materials, Doverlube NCEP performs well on aluminum and softer nonferrous materials to reduce chip size and scuffing.

Laboratory Testing Data Oil-based Formulations

All of the alternative chemistries in this test are chlorine-free. The sulfurized (27% active) Mayco Base 1540 provided superior performance to the long-chain chlorinated paraffin. Two other additives also yielded better draw efficiency: Doverphos 253, a dioleyl hydrogen phosphite, and Mayco Base 1351 sulfurized fat with 10% sulfur.


All of the above chlorine-free additive chemistries provide equivalent tapping performance to the long-chain chlorinated paraffin. Performance of the nitrated vegetable oil compound Doverlube NCEP is enhanced by synergies with both Mayco Base sulfurized additives, which are more dramatically demonstrated in the drawing performance data below.


All three of the alternative additives provide equivalent or better drawing performance than the long-chain chlorinated paraffin, and synergies between them enhance that. The additive blend 90:10 Mayco Base 1351 (10% S)/NCEP provides significantly superior performance.

Conclusions
The data from Dover’s bench tests presented here generally agree with that of customers’ field trials. Dover offers many chlorinated paraffin alternatives for metalworking fluid formulations used in both metal removal and forming applications of steel, stainless, low-ferrous alloys and exotics. Dover continues to supply the market with midchain and long-chain CPs, the most versatile, cost-effective and easiest-to-formulate additives. We also are helping metalworking formulators and blenders transform their technologies to meet evolving global regulations and fill market needs for greener products.

For Formulary Assistance Contact:
Lou Bona, Global Business Manager, Metalworking: lbona@doverchem.com, or
John Nussbaumer, Metalworking Chemist: jnussbau@doverchem.com.

For Regulatory Questions/Guidelines Contact:
Tom Kelley, Global Business Director, Chlorinated Products/Flame Retardants: tkelley@doverchem.com.