Cutting fluid is widely used in cutting because of its cooling, lubrication, cleaning and rust prevention functions. Cutting fluid in the use of often metamorphic odor, corrosion, foam, the use of the operator skin allergy and other problems, combined with our practical experience in the work of the following, talk about the use of cutting fluid problems and countermeasures.

一, the problem of cutting fluid deterioration and odor

The main reason for the deterioration and odor of the cutting fluid is that the cutting fluid contains a large number of bacteria, and the bacteria in the cutting fluid are mainly oxygen consuming bacteria and anaerobic bacteria. Oxygen-consuming bacteria live in the environment with minerals，such as water, cutting fluid concentrates, and oil from machine tools, and divide in two every 20-30 minutes under aerobic conditions. While anaerobic bacteria live in the environment without oxygen, every hour divided into two, the metabolism released sulfur dioxide, rotten egg taste, cutting liquid turned black. When the bacteria in the cutting fluid is greater than 100, the cutting fluid will become smelly.

(1) Bacteria enter the cutting fluid mainly through the following channels:

     1) There is bacterial invasion in the preparation process, such as bacteria in the water of the preparation cutting fluid.

     2) Bacteria in the air enter the cutting fluid.

     3) The transfer between workpiece processes causes the infection of cutting fluid.

     4) Operator's bad habits, such as throwing dirty things.

     5) Poor cleanliness of machine tools and workshops.

(2) Methods to control bacterial growth

     1) Use high quality, good stability of cutting fluid.

     2) The concentrated solution prepared with pure water is not only easy to prepare, but also can improve the lubricity of the cutting fluid, reduce the amount taken away by chips, and prevent bacterial erosion.

     3) When used, the ratio of concentrated liquid in cutting fluid should not be too low, otherwise it is easy to make bacteria grow.

     4) Because the oil used in the machine tool contains bacteria, the oil leaked from the machine tool should be mixed with the cutting fluid as much as possible.

     5) When the pH value of the cutting fluid is 8.3 ~ 9.2, it is difficult for bacteria to survive, so new cutting fluid should be added in time to improve the pH value.

     6) Keep the cutting fluid clean, do not make the cutting fluid and dirty oil, food, tobacco and other dirt contact.

     7) Often use fungicides, Combat BV is a good choice.

     8) Keep the workshop and machine tools clean.

     9) If the equipment does not have a filter device, it should be regularly skimming oil slicks and removing dirt.

二, the corrosion of cutting fluid

（1）Causes of corrosion

     1) The proportion of concentrated fluid in cutting fluid is low.

     2) The pH of the cutting fluid is too high or too low. For example, when PH > 9.2, it has a corrosive effect on aluminum. Therefore, the appropriate pH value should be selected according to the metal material.

     3) Contact with dissimilar metal materials.

     4) Lay out the workpieces with paper or wood pads.

     5) Stacked parts.

     6) The number of bacteria in the cutting fluid exceeds the standard, and the fungicide is not correctly added.

     7) The humidity of the working environment is too high.

（2）,  Corrosion prevention methods

     1) the cutting fluid is prepared with pure water, and the proportion of the cutting fluid should be used according to the recommended value in the manual of the cutting fluid.

     2) In the case of need, to use antirust solution.

     3) Add bactericidal preservatives to avoid the production of bacteria.

     4) Check the humidity and pay attention to controlling the humidity in the working environment within the appropriate range.

     5) To avoid cutting fluid pollution.

     6) Avoid contact with dissimilar materials, such as aluminum and steel, cast iron (containing magnesium) and copper.

三, the problem of bubbles

In the use of cutting fluid, sometimes cutting fluid surface will produce a lot of foam.

(1) The main causes of bubbles

     1) The level of the cutting fluid is too low.

     2) the flow rate of cutting fluid is too fast, and the bubbles do not have time to overflow, which leads to a large number of bubbles.

     3) Too many right angles in the flume design, or the nozzle Angle of the cutting fluid is too straight.

(2) Ways to avoid bubbles

     1) In the centralized cooling system, the pipes are in series in stages, and the pressure of the pipes near the cooling box should be lower.

     2) Ensure that the liquid level of the cutting fluid is not too low, check the liquid level height in time, and add cutting fluid in time.

     3) Control the flow rate of cutting fluid not too fast.

     4) In the design of the sink, should pay attention to the sink not too many right angles.

     5) In the use of cutting fluid should pay attention to the cutting fluid nozzle Angle is not too straight.

四, the operator's skin allergy problem

(1) The main cause of the operator's skin allergy

     1) The pH value is too high.

     2) the composition of cutting fluid.

     3) Insoluble metal and oil used in machine tools.

     4) The ratio of concentrated liquid is too high.

     5) Protective suspension layer on the surface of cutting fluid, such as odor sealing layer and anti-foam layer. Fungicide and dirty cutting fluid.

(2) In the work, in order to avoid the operator's skin allergy, we should pay attention to the following points

     1) The operator should apply protective oil, wear work clothes and gloves, and pay attention to avoid direct contact between skin and cutting fluid.

     2) the proportion of concentrated liquid in the cutting fluid must be used in accordance with the recommended value of the cutting fluid.

     3) The dosage of fungicide should be used according to the instruction manual.

In addition, fluorine rubber and grease rubber are affected by cutting fluid and have small deformation, which can be given priority when used as machine tool seals. In order to prevent deformation, the grease content of rubber used in machine tool seals should generally be greater than 35%. In addition, in order to effectively prevent the cutting fluid caused by machine paint peeling, epoxy resin paint or polycoelomester paint can be selected.

In short, the use of cutting fluid in normal production, if you can pay attention to the above problems, can avoid unnecessary economic losses, effectively improve production efficiency.