Hot weather cutting fluid smell, how to prevent?

Why does cutting fluid smell?

Microbial growth

There are a lot of organic matter in the cutting fluid including base oil and various lubricating additives which may constitute the carbon source of microbial growth. The amine used to maintain pH is a good source of nitrogen, and many carbon and nitrogen components also have the function of energy. The water in the mixing liquid contains a large number of minerals and the metal parts processed contain a variety of alloying elements, which is the ideal growth environment for microorganisms.

Species and hazards of microorganisms

The microflora in cutting fluid is quite extensive. The classification and naming of microorganisms is complex. According to their different needs for oxygen, microorganisms can be divided into aerobic bacteria, anaerobic bacteria and facultative anaerobic bacteria.

For cutting fluid, anaerobic bacteria are more harmful. Although anaerobic bacteria are not normally able to grow, because of the formation of colonies, the growth of aerobic bacteria will create conditions for anaerobic bacteria, because the breeding of aerobic bacteria to create food conditions for anaerobic bacteria.

How to prevent cutting fluid odor?

Lower the temperature

Most of the microorganisms encountered in the cutting fluid are thermotropic, and the most suitable temperature range for growth is 25-43℃. The effects of temperature beyond the growth range vary. Below the minimum temperature limit, the metabolic rate of microorganisms decreases, but above the maximum temperature limit, protoplasm metamorphosis, loss of functional coordination, abnormal metamorphosis, resulting in death.

Increase PH

Each microbe has an optimal pH and a certain range of adaptation, and the optimum range for most bacteria and protists is 6.5-7.5. Enzyme activity is highest in the most suitable pH range, promoting microbial growth. The following diagram shows the effect of different pH values in the cutting fluid on microbial growth. The results showed that when the pH range of cutting fluid was above 9, it could basically inhibit the growth of bacteria.

Increases the activity of the mechanism water

The growth of microorganisms in the cutting fluid on the surface of the relevant solid is largely dependent on the activity of the substrate water. Matrix water activity (αw) is usually defined as the ratio of the vapor pressure generated by water at the surface of the matrix to the vapor pressure of pure water. The substrate required for mold growth is very low in moisture, so it is easy to grow mold in some cutting fluid splash areas.

Radiation and ultrasonic sterilization

Through the transmission of electromagnetic waves, including radio waves, visible light, X-rays, gamma-rays and cosmic rays. In the range of visible light, short ultraviolet wave has strong bactericidal effect, may cause microbial chromosome aberration, so as to play a bacteriostatic effect. The mechanism of ultrasonic sterilization is that it can shock microbial cells, the higher the frequency, the more significant the effect.

Prevention of microbial growth

At present, oil-water separator is widely used for the prevention of microorganisms. Oil and water separator can efficiently remove the surface of the oil slick, so that the cutting fluid and oxygen are fully mixed, can inhibit the growth of bacteria and other microorganisms, so as to ensure that the cutting fluid does not stink.

So some people will say, so the selection of oil machine cutting fluid can not solve the problem? This is relative, oil machine cutting fluid cost high precision equipment. Therefore, we need to analyze the specific problems.

How to choose cutting fluid?

Use of water - based cutting fluid

Because in the common liquid and solid material, the specific heat capacity of water is the largest, and the main component of water based cutting fluid is water, so the cooling performance of water based cutting fluid is very good, especially suitable for large heat occasions. Machine tool in high-speed cutting and rough machining of parts, is a typical occasion of large heat, so it is more suitable to use water-based cutting fluid.

Water-based cutting fluid can quickly reduce the temperature of the cutting tool and workpiece processing area, excellent cooling effect, and timely take away the cutting chips, play a cleaning role, rust prevention agent in the cutting fluid can effectively prevent the workpiece rust, has a good rust prevention effect, because its main component is water, and has good economy.

Selection of oil-based cutting fluid

The main characteristics of oil-based cutting fluid are excellent lubrication, corrosion prevention and corrosion prevention. When the durability of the tool has a greater impact on the economy of cutting, such as the price of the tool is expensive, grinding tool is difficult, should choose the oil base cutting fluid lubrication tool; And for high precision, absolutely do not allow water to mix (so as not to cause corrosion) of high-end machine tools, must choose oil-based cutting fluid; Where the lubrication system and cooling system of machine tools are easy to collude and where there is no waste liquid treatment equipment and conditions, oil-based cutting fluid should also be considered.

In short, in the machining industry, the selection of machine tool cutting fluid is a very important work. The selection of water-based cutting fluid or oil-based cutting fluid should be analyzed according to the specific processing situation. Reasonable selection of cutting fluid can bring good help to the processing.