Understanding the purpose of ASTM tests for corrosion resistance of lubricating greases

ASTM standard tests are recognised industry benchmarks to ensure greases perform to their best capabilities of corrosion protection under the demanding operating conditions. These tests help to ensure that the right greases are used as rust and Corrosion Protectors.

Today, there are many varieties of greases available in the market. Each has varying properties of lubrication to keep machine components and bearings running optimally under the demanding operating conditions such as high temperature, speeds and loads. In addition, these greases are also expected to protect the machinery components against corrosion due to the environmental factors like exposure to water, corrosive chemicals, fumes, high humidity etc.

At Molygraph, we have devised our own stringent test methods based on the ASTM standards to ensure that greases featuring different chemistry levels can be tested for use in the real world. They are:

1. ASTM D 6138, which is an EMCOR Rust test
2. ASTM D 1743, which is a Corrosion Preventive Test
3. ASTM D 4048, which is a Copper Corrosion Test

Let’s briefly analyse these tests:

1. ASTM D 6138

New bearings that are cleaned and lubricated are immersed partially in water with no applied load. It is set to a speed of 83 ± 5 rpm in a sequence of running and stopping for 1 week. After a week, the bearings are cleaned, examined and rated based on the degree of corrosion experienced.

2. ASTM D 1743

New bearings that are cleaned and lubricated are made to run under a thrust load for 60 ± 3 sec to spread the lubricant in the form of a pattern that can be found in service. Water is passed through the bearings, which is then stored for 48 ± 0.5 h at 52 ± 1°C with 100% relative humidity. After this process, the bearings are examined for signs of corrosion.

3. ASTM D 4048

A copper strip is placed inside a grease sample and heated in a liquid bath or oven at 100 ± 1 °C for 24 h ± 5 min. After this process, the strip is washed and compared with the standard chart for copper strip corrosion.

The purpose behind these tests is to ensure that we formulate the high performing greases that offer the best corrosion protection in the harshest environments.

Molygraph makes a wide range of High Performance Specialty Industrial Lubricants that deliver the best value with longer operating life, lower maintenance needs and higher productivity for your machinery and components. Get in touch us with us by calling us at +91 81044009925 or sending an email to sales@molygraph.com. You can also explore our range of rust preventive oils and other specialty lubricant products that can serve your industry needs brilliantly.