Ashless Antiwear and Extreme-Pressure Additives 239
In other product categories, lubricant and additive suppliers, OEMs, and industry trade associa-
tions work together to determine performance requirements and product specifi cations. In addition
to the three industry organizations mentioned earlier, the National Lubricating Grease Institute
(NLGI), the National Marine Manufacturers Association (NMMA), the American Gear Manufac-
turers Association (AGMA), the Society of Tribologists and Lubrication Engineers (STLE), and
other groups, associations, and key equipment builders can infl uence lubricant specifi cations.
In addition to meeting all military and industrial specifi cations, many leading lubricant mar-
keters and fi nished lubricant suppliers develop their own internal specifi cations to be used for new
product launching, competitive product analysis, and future product development. Proprietary fi eld-
testing is an integral part of the overall new lubricant product development processes and is often
the most critical step to assure technical success and customer satisfaction for new products.
8.4.2 ADDITIVE SPECIFICATIONS
Specifi cations for antiwear/EP additives focus primarily on application, base oil compatibility, and
quantifi cation of elemental constituents. In addition, specifi cations typically identify specifi c and
critical performance standards for applications. Common specifi cations for antiwear/EP additives
are shown in Table 8.4.
In addition to typical specifi cations as reported in the Certifi cate of Analysis (C of A) from
additive suppliers, individual lubricant marketers often prefer to conduct their own internal additive
specifi cations, such as infrared analysis and key performance testing.
8.4.3 TEST METHODS AND EQUIPMENT
In the United States, a number of bench and advanced tests were developed and approved by ASTM,
and these tests have gained widespread reception throughout the industry. However, there are also a
few selected lab-bench and advanced tests that were developed and approved only by specifi c OEMs,
but represent certain critical and desirable performance features (Figures 8.2 and 8.3). This chapter
is not intended to cover all evaluation tests in detail, but rather to illustrate a few representative tests
to highlight the key assessment criteria.
- Four-Ball Wear and EP Test. This tester was developed to evaluate the antiwear, EP, and
antiweld properties of lubricants. It is a simple bench test machine designed to measure the
protection a lubricant provides under conditions of high unit pressures and various sliding
velocities. The Four-Ball Wear tester consists of four 1.5 in. diameter steel balls arranged
in the form of an equilateral tetrahedron. The three lower balls are held immovably in a
TABLE 8.4
Typical Specifi cations for Antiwear and EP Additives
Chemical Class Property Performance Test
Amine phosphates Percent of nitrogen,
phosphorus, and TAN/TBNFour-Ball Wear, Four-Ball EP,
FZG, rust/oxidation test
Methylene bis-dialkyl dithiocarbamate Percent of sulfur, nitrogen,
and residual chlorine, amineFour-Ball EP, FZG, Falex EP,
oxidation/corrosion test
Sulfurized lard, esters, fatty acids Percent of total sulfur Four-Ball Wear, Four-Ball EP,
Percent of active sulfur stick-slip, Cu corrosion
Triphenyl phosphorothioate Percent of sulfur, phosphorus,
and melting pointFour-Ball EP, FZG, Falex EP,
oxidation/corrosion test
Chlorinated paraffi ns, fatty acids Percent of chlorine Four-Ball Wear, Falex EP,
Acid value Timken, Cu corrosion