Changes in the quality of grease include physical and chemical changes:

Grease in part because of the role is influenced by the external environment (such as air, water, dust and other harmful gases, etc.) were studied, and the working parts of the relative motion to generate mechanical forces (such as stamping, cut, etc.) will occur changes in two aspects:

(1) chemical changes: Grease group points (base oil, thickening agent) due to the light, heat and air may cause oxidation deterioration, the base oil subjected to oxidation generated trace organic acids, aldehydes, ketones and lactones, thickener in fatty acids, organic metal salt may decompose and the formation of trace organic acid and, therefore, produce acidic substances, acid number of lubricating grease increases lead to be lubricated parts corrosion and corrosion even and loss of lubrication and protection.

(2) physical changes: due to the mechanical effect of the structure of lubricating grease variation and failure, decrease of grease consistency, lubricating effect becomes worse, or is due to parts of lubrication sealing condition is not good, resulting in mixed with grease in the dust, impurities and moisture and grease quality variation.

Discriminant method: (1) grease with the naked eye or feel the dust, impurities, or by mixing water grease emulsification and white, shallow, or consistency significantly smaller or obvious fat rancidity odor, can explain the deterioration of the lubricant.

(2) the instrument analysis method, the most direct discrimination and the use of a small amount of samples by infrared spectrometry was used to determine sample contains 1720cm-1 absorption peak. Or determination of samples in before and after the use of the absorption peak of carbonyl index for 1710cm-1 1378cm-1 two absorption peak ratio. Or direct determination of acid value, if the acid number is more than 1.0 mgKOH / g that ensure grease has started to deteriorate.

How to identify grease deterioration:

Grease is different from the lubricating oil, in the absence of instrument testing site, you can use a simple method to determine the performance of its good or bad, the test method is as follows:

(1) no matter what color is the grease concept, body fat should be uniform sticky paste. If you open the packaging and found that body fat on the surface of the oil slick, the surface color of fat deep wash or cuticular hardening, or consistency was significantly smaller, or surface grease mixed with moisture and emulsification turned white, these phenomena may are stored for too long qualitative change, packaging or not sealed lead to a qualitative change, these lipids are not available.

(2) smell when you open the package has obvious oil rancid smell, that fat body had deteriorated and is not available.

(3) dry pinch general without filler of grease is used for touch pinch with smooth viscous feeling, but no astringent silting phenomenon. If thickener dispersion uneven or impurities, then obviously there is slightly in susceptible and non slippery, the fat is not available.

(4) look at the packaging production date generally should be selection of oil production date in front, because different types of grease products have different shelf life should be determined with the supplier, the shelf life of special grease generally have 36 months.

(5) fat burning body is a reference method with fire with a lighter ignition, low drop point detection. This method can be used to inferior fat

(6) the sun a piece of fat in the cup in the sun for a day or two, if the change of lipid body, oil or discoloration, its performance is unstable and is not available.

(7) water method take a small amount of fat added a few drops of water in the above, stirring with a small glass rod, if appear turbid, milky white fat emulsification, not water resistance grease.

Example: test the deterioration of bearing grease

In the course of the use of bearings, grease is very critical. If the use of the deterioration of the grease, not only can not play the role, but also damage to the bearings.

(1) oil flow observation method
Take two cups, wherein a Sheng to be check lubricating oil, another empty placed on the desktop, filled with lubricating oil measuring cup cite high left desktop 30-40 cm and tilt, let oil slowly flows to the empty cup, to observe the flow and good quality of the lubricating oil flow should be the is slender, uniform, continuous, if the oil flow unsteadiness, sometimes large shed, said lubricating oil has been deterioration.

(2) hand twisting method
The lubricating oil twist in the repeated grinding between thumb and forefinger, good lubricating oil hand feel with lubrication, less debris, no friction, if you feel sense of larger sand grains such as friction between the fingers, it indicates that the impurity in the lubricating oil, can't use should be replaced with new oil.

(3) light method
On sunny days, using a screwdriver will be lifted the lubricating oil, at a 45 degree angle with the horizontal plane. Against the sun, observe the oil droplets, under illumination, clearly see the lubricating oil in no debris as well, to continue the role, if excessive debris, should replace the lubricating oil.

(4) oil drop mark method
Take a clean white filter strips, oil drop a few drops on the filter paper test, the leakage of the lubricating oil to be, if the surface black powder, touch resistance acerbity feeling, lubricating oil inside the impurity has a lot of, good oil no powder, dry and smooth to touch and a yellow color traces.

The above information is provided by Shenzhen EUBO, the best of the world's leading lubrication solutions!