Jalos Studies Lube Test Methods

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Japan Lubricating Oil Society recently reported results of studies that it completed into the accuracy of test methods for friction, wear and load-bearing capacity of lubricants. The testing is part of the organization’s ongoing effort to improve lubricant quality.

The association conducted research and tests last year and in previous years as well. “The purpose of the study is to examine the correlation of test results from the Soda-type four-ball friction tests and the standard four-ball friction test,” a Jalos official told Lube Report, commenting on the latest test findings.

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The Soda-type four-ball wear tester was introduced in Japan in recent years and assesses the extreme-pressure performance and friction performance of lubricants. The apparatus tests the level of boundary friction and the strength of boundary oil films, which give references for comparing the oiliness of lubricants. It complies with JIS K 2519, a specification for lubricant testing methods for load-carrying capacity that specifies two types of testing methods. The two types are the Soda method – which tests load-bearing capacity using a four-ball apparatus – and the Timken method – which uses a Timken extreme pressure tester.

To study the test methods of lubricants, Jalos examined in detail the relationship between the structure of a sulfur-based extreme pressure agent and extreme pressure protection by observing the wear scars on the ball and disk of the test sample after a ball-on-disk test.

“There are various types of extreme pressure agents such as sulfur-based, phosphorus-based, organometallic, and halogen-based extreme pressure agents,” the official said. “For this test, we decided to select a sulfur-based compound with a known structure. Sulfur-based extreme pressure agents are common additives used in gear oils and metalworking oils.

“In the future, if we can obtain a test sample with a known structure, we would like to study phosphorus-based or a combination of sulfur-phosphorus-based agents and would also like to study the structure and performance of organometallic-based additives.”

Jalos evaluated eight types of sulfur-based extreme pressure agents with known properties and mixed 2.4% of it with paraffin-based API Group II base oil and conducted a ball-on-disk test with a vibration friction tester to evaluate properties of extreme pressure. The results showed superior extreme pressure properties and a higher maximum load test for a test oil that used a fat-based, sulfur-based extreme pressure agent. This test oil was compared to an oil that instead used a sulfur olefin-based, sulfur-based extreme pressure agent.

Jalos was established in 1978 under the Ministry of International Trade and Industry to promote the activities of the lubricant industry. Among its activities are experiments and research, training, and information collection. Its membership of 149 is made up mainly of lubricants and additives manufacturers and users.