Views: 0 Author: Site Editor Publish Time: 2022-06-22 Origin: Site
1. Classification of cutting fluid
Water - based cutting fluids can be divided into emulsion, semi-synthetic cutting fluids and fully synthetic cutting fluids.
The classification of emulsion, semi-synthetic, and total synthetic is usually determined by the type of base oil in the product: emulsion is a water-soluble cutting fluid that uses only mineral oil as the base oil; Semi-synthetic cutting fluid is water-soluble cutting fluid containing both mineral oil and chemical synthetic base oil. Fully synthetic cutting fluids are water-soluble cutting fluids that use only chemically synthesized base oils (i.e., no mineral oils).
Each type of cutting fluid will contain a variety of additives in addition to the base oil: rust inhibitor, non-ferrous metal corrosion passivation agent, defoaming agent, etc.
Some manufacturers will have microemulsion classification; generally considered a category between emulsion and semi-synthetic cutting fluids.
The diluent of the emulsion is milky white in appearance; the diluent of semi-synthetic liquid is usually translucent, and some products are milky white. Diluents of total synthetic solutions are usually completely clear as water or tinged with some color.
Cutting fluid is widely used in cutting because of its functions of cooling, lubrication, cleaning and rust prevention. Cutting fluid often appears in the use of deterioration, odor, corrosion, foam, the use of operator skin allergy and other problems, the following combined with our practical experience in the work, talk about the use of cutting fluid problems and countermeasures.
2. The problem of cutting wave deterioration and stench
The main reason for the deterioration of cutting fluid is that there are a lot of bacteria in the cutting fluid, and the bacteria in the cutting fluid are mainly oxygen consuming bacteria and anaerobic bacteria. Oxygen-consuming bacteria live in the presence of minerals such as water, concentrated cutting fluid and oil from machine tools and divide into two every 20 to 30 minutes under aerobic conditions. Anaerobic bacteria live in the absence of oxygen, splitting into two every hour, releasing SO2, which smells of rotten eggs and turns cutting fluid black. When the bacterium in the cutting fluid is greater than 106, the cutting fluid will become smelly.
(1) Bacteria enter into the cutting fluid mainly through the following channels:
1) There is bacterial invasion in the preparation process, such as bacteria in the water where the cutting fluid is prepared.
2) Bacteria in the air enter the cutting fluid.
3) Transfer between workpiece processes causes infection of cutting fluid.
4) Bad habits of operators, such as littering dirty things.
5) Poor cleanliness of machine tools and workshops.
(2) Methods to control bacterial growth
1) Use high-quality and stable cutting fluid.
2) The concentrate 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 using, the ratio of concentrated liquid in cutting fluid should not be too low, otherwise it is easy to make bacteria grow.
4) As there are bacteria in the oil used in the machine tool, it is necessary to reduce the oil leakage from the machine tool mixed with the cutting fluid as much as possible.
5) When the pH value of cutting fluid is between 8.3 and 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) Use fungicides frequently.
8) Keep the workshop and machine tools clean.
9) If there is no filter device, the oil slick should be skimmed regularly to remove dirt.
3. The corrosion of cutting fluid
(1) Causes of corrosion
1) The proportion of concentrated liquid in cutting fluid is low.
2) The pH value of cutting fluid is too high or too low. For example the cutting fluid corrodes aluminum when PH > 9.2. Therefore, the appropriate pH value should be selected according to the metal material.
3) Dissimilar metal material contact.
4) Pad the work piece with paper or wood.
5) Stacked parts.
6) The number of bacteria in the cutting fluid exceeds the standard.
7) The humidity in the working environment is too high.
(2). Methods of corrosion prevention and control
1) Prepare the cutting fluid with pure water, and the proportion of the cutting fluid should be used according to the recommended value in the cutting fluid manual.
2) In the case of need, to use anti-rust fluid.
3) Control the number of bacteria to avoid the generation of bacteria.
4) Check the humidity and control the humidity in the working environment within the appropriate range.
5) To avoid contamination of the cutting fluid.
6) Avoid contact with dissimilar materials, such as aluminum and steel, cast iron (containing magnesium) and copper, etc.