Lubricant tests

Fig. 4. Opera ting principles of various laboratory lubricant-test machines.

Both friction and wear measurements have been used to study boundary lubrication of fuel because sticking fuel controls and pump failures are primary field problems in gas turbine operation. An extensive research program of the Coordinating Research Council has produced a baH-on-cylinder lubricity test (BOCLE), standardized as ASTM D5001, which is used to qualify additives, to investigate fuels, and to assist pump manufacturers (21). 

FIGURE 6-16. Schematic Arrangements of Lubricity Test Machines... 

Other emulsion test methods are used to rate the ability of fuel to shed water. These methods include ASTM D-1401 and the Waring Blender Test. The ASTM D-1401 method is a lubricant test method, but has been adopted by the U.S. military for rating diesel fuel demulsibility.This method is summarized by ASTM as follows ... 

A previous edition of the dimensions standard also had a method intended for compression set test pieces which was similar except that the force on the foot was 850 30 mN and the contact members were either domed surfaces of 12.5 mm radius or a spherical contact of 6.35 mm diameter and a raised platform of 9.5 mm diameter. This use of curved surfaces for compression set is based on the fact that after compression, particularly with non-lubricated test pieces, the rubber may well have concave surfaces. This does not happen if the test piece is lubricated as is now the usual practice and, hence, the curved surfaces were eliminated. However, if concave test pieces are encountered it may well be better to resort to the old method... 

The friction coefficient drops to a value below 0.05, characteristic of ultralow friction. This is a well known phenomenon encountered when using MoDDP additives in lubricating tests (Tung et al., 1988 Zheng et al., 1986). This demonstrates that the ultralow friction is mainly due to a tribochemical transformation of the solid reaction film. In the ASE spectrum analysis a molybdenum sulfide tribofilm formed on the wear scar showed a S Mo peak ratio near 9, which is in agreement with a pure MoS2 spectrum. 

In any manufacturing operation, many miscellaneous supplies are needed to keep the process functioning efficiently. Items such as charts, lubricants, test chemicals, custodial supplies, and similar supplies cannot be considered as raw materials or maintenance and repair materials, and are classified as operating supplies. The annual cost for this type of supplies is about 15 percent of the total cost for maintenance and repairs. 

Laich,T., and Kissel,T. (1998), Automatic adaptation of lubricant quantity by control of an external lubrication. Tests on a reciprocating and on a rotary tablet press, Pharm. Ind., 60(10), 896-904. 

An initial problem with lubricant development was that engine manufacturers regarded their individual products as unique by metallurgy, design and use. Individual manufacturers wanted special lubricant tests in addition to general lubricant... 

The ILSAC system, developed by US and Japanese OEMs, has started to progressively rationalise lubricant tests on an international basis leading to the GF-... 

Different engine lubricant testing approvals arise from different attitudes and philosophies in different continents and also different countries within those continents. Issues are now addressed internationally by new test method development and procedures for specifying lubricant qualities, leading to new approval systems. These developments benefit engine and equipment manufacturers, producers of lubricants and additives and, ultimately, users of mechanical systems of whatever form in an eventually international marketplace. 

Realistic engine tests are only meaningful over field trials lasting 1 year, or more. But what is realistic - the variety of engine use is almost as varied as life itself. To address this, international committees have defined engine lubricant tests which are practical, relevant to use and reproducible under tightly defined conditions. 

The general principles of engine lubricant testing address issues of ... 

To meet these aims for light vehicle lubricant formulations, each engine test has a characteristic criterion or set of criteria, some examples are given in Table 17.2. These light engine lubricant tests are used for either or both petrol- and diesel-fuelled light vehicles as components of API or ACEA test procedures. 

Table 17.2 Engine lubricant tests for light vehicles, petrol/diesel ...

In 1977, approvals were placed with the SAE as the Lubricants Review Committee of the Lubricants Review Institute (LRI), and this worked well for a decade. Engine lubricant test policy changes and strengthened API classifications, described below, gave lubricant companies and also end users more confidence, reducing the need for US military approvals. The influence of the LRI diminished, and the US military questioned the approval process cost-effectiveness and whether it should source lubricants at the appropriate API quality as a commercial item description instead. 

On the one hand, the cost and practical difficulties of establishing US/European tests for individual countries/blocs were prohibitive. Equally, time required, delays and costs of running engine lubricant tests in Europe/United States is expensive of a currency in short supply. As trading barriers are being removed or reduced and business globalisation increasing, then the continued use of parallel test procedures becomes unnecessary. 

The flash temperature is also related to types of tribomachines. Each type of machine has its specific type of contact geometry and style. For example, on a four-ball lubricant testing machine, the flash temperature is totally different from that of a sliding pin on disk. The A7max temperature for a standard four-ball wear contact may be calculated from a Blok equation 18... 

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