Lube-Tech PUBLISHED BY LUBE: THE EUROPEAN LUBRICANTS INDUSTRY MAGAZINE
Metalworking fluids in use I would first draw your attention to my article Neadle D. (2010) Control and Maintenance of Metalworking Fluids, Lube Magazine Lube-Tech, 73, pp. 21-24. Metalworking Fluids undergo changes in service which may have an effect on the health of those who work with them, particularly machine operators.
The characteristics of fresh fluids are altered by service. The changes may be slight or significant and are likely to be progressive unless appropriate corrective actions are taken. The rate of change in fluids depends on their conditions of use.
In the case of water-mix fluids, concen- tration usually increases and pH falls in service. Contaminants may enter both neat oils and water-mix fluids, for example lubricating and hydraulic oils, solvents, greases and metals in dissolved or particulate form*.
Oxidation can also lead to deterioration of fluids. In neat oils, oxidation can result in the development of acidity and formation of sticky deposits which interfere with the operation of machine tools. Dissolved metals derived from the machining process accelerate the deterioration process (iron and copper are strong pro-oxidation catalysts).
Concentrations of several hundred parts per million of dissolved lead can build up in neat oils. Cobalt can become dissolved in water-mix fluids used for grinding hard metals, if specially formulated fluids are not selected.
A Condition Monitoring Programme can be very effective in detecting changes in metalworking fluids in service and identifying trends and sudden events. Water-mix fluids in service would typically be tested for concentration, pH value, corrosion resistance and contamination by lubricants, metals and micro organisms. The tests for neat oils could include viscosity, flash point, infra-red analysis, acid value, elemental analysis and particulate content.
Routine testing for micro organisms in water-mix fluids is usually carried out using slides coated with nutrient media. The slides are dipped into the fluid in use and incubated before being examined for growth of colonies in comparison with standards. Determination of more specific information about the types of micro organisms present and their signif- icance requires the special expertise of the microbiologist.
* When examined microscopically, metal particles generated in cutting and grinding operations are found to be very
No.76 page 3
sharp. They can inflict damage upon the skin, especially when embedded in wiping cloths or work wear. The resulting disruption of the skin’s outer protective layers facilitates further penetration of oils and chemicals. Damage to the skin produced in this way is progressive and healing can be very slow and problematic.
The aftermath of Powertrain Investigations following the Powertrain outbreak led to the conclusion that the respiratory diseases were associated with exposure to mists from contaminated water-mix metalworking fluids (and possibly cleaning fluids) and the presence of micro organisms.
Following the outbreak of respiratory diseases at Powertrain, the HSE published new guidance including the following recommendations: • A risk assessment should be carried out.
• Metalworking fluids in use should be monitored and controlled (monitoring to include testing for micro organisms).
• Exposure to metalworking fluids and the mists, fumes and vapours from them should be controlled
• Health surveillance should be provided for those exposed to metalworking fluids.
The Health and Safety Executive is promoting awareness of these issues through fieldwork and the Health and Safety Laboratory is carrying out research with the objective a reaching a deeper understanding of the causes of the respiratory diseases.
There is a vast amount of literature available on the association between metalworking fluids and respiratory diseases. Unfortunately, the reports from different sources do not allow meaningful comparisons and conclusions. However, there does appear to be a strong linkage between the presence of high numbers of micro organisms (or substances derived from them) and respiratory ill health.
LUBE MAGAZINE No .103 JUNE 2011
23
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44
