The microbiology of metalworking fluids

Abstract

Metalworking fluids (MWFs) are complex mixtures of chemicals and are indispensable materials in industry. They are used as cooling and lubricating agents in different machining process such as grinding, milling, and cutting. The quality of MWFs is affected by physical, chemical, and microbial contaminates. In particular, MWFs are highly vulnerable to microbial contamination, which may act both as potential pathogens and deteriorgens. Microbial contamination is of major concern due to potential health hazards such as skin dermatitis and hypersensitivity pneumonitis. The contaminated MWFs can exhibit high degrees of microbial loading, ranging from 10(4) to 10(10) colony-forming units (CFU)/ml. Wide varieties of microorganisms are reported to colonize MWFs. Traditional culturing techniques are not only laborious and time consuming but also underestimate the actual distribution of the microorganisms present in the contaminated MWFs. Therefore, rapid molecular methods such as real-time PCR and fluorescent in situ hybridization are implemented to monitor the microbial load. In industry, biocides are presently used to control microbial contamination. However, it has its own disadvantages and therefore, in recent years, alternative methods such as UV irradiation were evaluated to reduce microbial contamination in MWFs. Microbes inhabiting the MWF are also capable of forming biofilm which is detrimental to the MWF system. Biofilm is resistant to common disinfectant methods, and thus further research and development is required to effectively control its formation within MWF systems. This review is intended to discuss the overall microbiological aspects of MWF.

Microorganisms in metalworking fluids: Current issues in research and management

“…In the European Union, the regulations regarding the permissible level of microbial contamination in MWFs have not been yet established. Also, a consensus on research techniques and the rational principles of microbiological monitoring of MWF's installations has not yet been reached [1,4]. The scarce data, accessible in the literature are difficult to interpret because different analytical procedures and sampling techniques of MWFs are used in the individual EU countries.…”

“…Growth of microorganisms in biofilms significantly changes the way of assessment of the contamination level of MWFs, and guides the selection of the most effective ways to prevent fluid overgrowth in industries devoted to metal shaping. The importance of biofilm in-depth research on reducing the exposure of workers to bioaerosols in the metal industry has recently been clearly highlighted by Saha and Donorfio [1]. Biofilms are common in the installations of pharmaceutical, food and metal industries.…”

Bioremediation Of A Spent Metalworking Fluid With Auto- And Allochthonous Bacterial Consortia

“…Apart from oil-derived xenobiotics they contain a number of additives including biocides, heavy metals, surfactants and many other agents [3,11]. In addition, cutting fluids are often contaminated by various bacterial (both gram-negative and gram-positive) and fungal strains (for detailed information see the review articles [12][13][14][15][16]). Such indigenous microbial strains may be beneficial for their tolerance towards toxic chemical constituents; however, they are often pathogenic and can cause adverse effects on human health, especially on the respiratory system and skin [3,[17][18][19][20][21].…”

Biological and chemical hazards in water-mix metalworking fluids and mists

“…MWF includes a mixture of components such as mineral oils (typically from 3-10% of the content), water, buffering constituents, surfactants, antifoaming agent and re-odorants (Cyprowski et al, 2004;Hendy, Beattie and Burger, 1985). Additionally, biocides and corrosion inhibitors can be added to increase their shelf-life and minimise damage to machined metals (Gordon, 2004;Saha and Donofrio, 2012). Thus, in any given MWF there can be up to 60 different components present (Table 1.2) (Rabenstein et al, 2009).…”

“…The choice of modern MWF is very dependent on the type of machining and cooling applications being used (Saha and Donofrio, 2012). MWF includes a mixture of components such as mineral oils (typically from 3-10% of the content), water, buffering constituents, surfactants, antifoaming agent and re-odorants (Cyprowski et al, 2004;Hendy, Beattie and Burger, 1985).…”