Research On Biostability Of Water-based Metal Cutting Fluid

In this paper, aiming to the issue of biostability of water-based metal cutting fluid, the effects of four types of microbiocides and the combination of them on the biostability of water-based metal cutting fluid were studied. In addition, the action mechanisms of the microbiocides were discussed.Firstly, ten kinds of microbiocides were evaluated by inhibition zone method, then four kinds of microbiocides which have better bacteriostatic performance were selected out, such as A(BA60DX), B(HT), C(PCMC)and D(DCHA). They were alone added to the basic formula to prepare basic cutting fluid with qualified anti-rust property and good emulsion stability. Then they will be used for next study.According ASTM D3946-92《Standard Test Methods for Evaluating the Bacteria Resistance of Water–Dilutable Metalworking Fluid》, a platform was set up in the laboratory to evaluate the biological stability of water-based metal cutting fluid. Through this platform the effects of the microbiocides on the biostability of water-based metal cutting fluid was studied in details. The results showed that when they were used alone in water-based metal cutting, with the concentration of microbiocide increasing the biological stability of water-based metal cutting fluid gradually improved. When microbiocide A reached to 6% and B reached to 4%, they both had good anti-bacterial properties; and when microbiocide C only was 1% , it could provide good inhibition for fungi; in contrast, microbiocide D had bad anti-bacterial performance within selected concentration range. The results also showed that only a single microbiocide generally could not simultaneously play the role of anti-bacteria and anti-fungi. The tests showed that a single fungicide could not simultaneously inhibit breeding of bacteria and fungi. And one of bacteria and fungi are very few, the other will be breeding largely.On the basis of above-mentioned research, microbiocides A and B, A and C, B and C, B and D were combined to use in water-based metal cutting fluid. It found that compound microbiocides perform better than single microbiocide, but not ideal. On this basis, two sets of experiment were done, including the composition of microbiocide A, B and C and microbiocide A, B and D. The results showed that the biostability of water-based metal cutting fluid had improved significantly. While 4%A, 1%B and 1%C were combined, the biostability of water-based metal cutting fluid was perfect. And then the impacts on water -based metal cutting fluid's biostability of chloride ions and calcium ions in water were investigated. The results showed that with the concentration of chloride ions and calcium ion increasing, the biostability of water-based metal cutting fluid decreased significantly.Through staining of microorganism, it found that bateria and fungi could coexist in the water-based metal cutting fluid. The amount of bateria and fungi in water-based metal cutting fluid is not only relevant to the effect of microbiocides, but also to the balance of coexistence of bateria and fungi.